Table of contents

Extending the Minimal Supersymmetric Standard Model with three right-handed neutrino superfields is one of the best motivated scenarios for physics beyond the Standard Model. However, very little is known from observations about the high energy parameters of this model. In this paper we show, under the plausible assumptions that the neutrino Yukawa eigenvalues are hierarchical and the absence of cancellations, that there exists an upper bound on the smallest Yukawa eigenvalue stemming from the non-observation of the rare lepton decay μ→eγ. Furthermore, we show that this bound implies an upper bound on the lightest right-handed neutrino mass of approximately 5 × 10¹² GeV for typical supersymmetric parameters. We also discuss the implications of this upper bound for the minimal leptogenesis scenario based on the decay of the lightest right-handed neutrino and we argue that an improvement of sensitivity of six orders of magnitude to the process μ→eγ could rule out this mechanism as the origin of the observed baryon asymmetry, unless the neutrino parameters take very specific values.

It is known that certain AdS boundary conditions allow smooth initial data to evolve into a big crunch. To study this type of cosmological singularity, one can use the dual quantum field theory, where the non-standard boundary conditions are reflected by the presence of a multi-trace potential unbounded below. For specific AdS₄ and AdS₅ models, we provide a D-brane (or M-brane) interpretation of the unbounded potential. Using probe brane computations, we show that the AdS boundary conditions of interest cause spherical branes to be pushed to the boundary of AdS in finite time, and that the corresponding potential agrees with the multi-trace deformation of the dual field theory. Systems with expanding spherical D3-branes are related to big crunch supergravity solutions by a phenomenon similar to geometric transition.

We analyze patterns of remnant discrete symmetries that arise from U1^N theories by spontaneous breaking. We describe a simple, geometrical way to understand these patterns and provide methods for identifying the discrete symmetries and bringing them to the simplest possible form. Applications in GUT and string model building are briefly discussed.

This paper presents a complete algebraic analysis of the renormalizability of the d = 4 operator F²_μν in the Gribov-Zwanziger (GZ) formalism as well as in the Refined Gribov-Zwanziger (RGZ) version. The GZ formalism offers a way to deal with gauge copies in the Landau gauge. We explicitly show that F²_μν mixes with other d = 4 gauge variant operators, and we determine the mixing matrix Z to all orders, thereby only using algebraic arguments. The mixing matrix allows us to uncover a renormalization group invariant including the operator F²_μν. With this renormalization group invariant, we have paved the way for the study of the lightest scalar glueball in the GZ formalism. We discuss how the soft breaking of the BRST symmetry of the GZ action can influence the glueball correlation function. We expect non-trivial mass scales, inherent to the GZ approach, to enter the pole structure of this correlation function.

We show that the dressing transformation method produces a new type of dyonic Pⁿ magnon in terms of which all the other known solutions are either composites or arise as special limits. In particular, this includes the embedding of Dorey's dyonic magnon via P³⊂Pⁿ. We also show how to generate Dorey's dyonic magnon directly in the Sⁿ sigma model via the dressing method without resorting to the isomorphism with the SU(2) principle chiral model when n = 3. The new dyon is shown to be either a charged dyon or topological kink of the related symmetric-space sine-Gordon theories associated to Pⁿ and in this sense is a direct generalization of the soliton of the complex sine-Gordon theory.

We consider the four dimensional scale invariant N = 2SU quiver gauge theories with USp(2N) ends or SU(2N) ends with antisymmetric matter representations. We argue that these theories are realized as six dimensional A_2N−1 (0,2) theories compactified on spheres with punctures. With this realization, we can study various strongly coupled cusps in moduli space and find the S-dual theories. We find a class of isolated superconformal field theories with only odd dimensional operators D(ϕ) ⩾ 3 and superconformal field theories with only even dimensional operators D(ϕ) ⩾ 4.

We use the entropy function formalism introduced by A. Sen to obtain the entropy of AdS₂ × S^d−2 extremal and static black holes in four and five dimensions, with higher derivative terms of a general type. Starting from a generalized Einstein-Maxwell action with nonzero cosmological constant, we examine all possible scalar invariants that can be formed from the complete set of Riemann invariants (up to order 10 in derivatives). The resulting entropies show the deviation from the well known Bekenstein-Hawking area law S = A/4G for Einstein's gravity up to second order derivatives.

It is shown by both analytical methods and numerical simulations that extremely long living spherically symmetric oscillons appear in virtually any real scalar field theory coupled to a massless dilaton (DS theories). In fact such ``dilatonic'' oscillons are already present in the simplest non-trivial DS theory — a free massive scalar field coupled to the dilaton. It is shown that in analogy to the previously considered cases with a single nonlinear scalar field, in DS theories there are also time periodic quasibreathers (QB) associated to small amplitude oscillons. Exploiting the QB picture the radiation law of the small amplitude dilatonic oscillons is determined analytically.

The μνSSM provides a solution to the μ problem of the MSSM and explains the origin of neutrino masses by simply using right-handed neutrino superfields. We have completed the analysis of the vacua in this model, studying the possibility of spontaneous CP violation through complex Higgs and sneutrino vacuum expectation values. As a consequence of this process, a complex MNS matrix can be present. Besides, we have discussed the neutrino physics and the associated electroweak seesaw mechanism in the μνSSM, including also phases. Current data on neutrino masses and mixing angles can easily be reproduced.

We critically reexamine the standard applications of the method of kinematical endpoints for sparticle mass determination. We consider the typical decay chain in supersymmetry (SUSY) → ⁰₂ → → ⁰₁, which yields a jet j, and two leptons ℓ_n^± and ℓ_f^∓. The conventional approaches use the upper kinematical endpoints of the individual distributions m_jℓℓ, m_jℓ(lo) = min {m_jℓn,m_jℓf} and m_jℓ(hi) = max {m_jℓn,m_jℓf}, all three of which suffer from parameter space region ambiguities and may lead to multiple solutions for the SUSY mass spectrum. In contrast, we do not use m_jℓℓ, m_jℓ(lo) and m_jℓ(hi), and instead propose a new set of (infinitely many) variables whose upper kinematic endpoints exhibit reduced sensitivity to the parameter space region. We then outline an alternative, much simplified procedure for obtaining the SUSY mass spectrum. In particular, we show that the four endpoints observed in the three distributions m²_ℓℓ, m²_jℓn∪m²_jℓf and m²_jℓn+m²_jℓf are sufficient to completely pin down the squark mass m and the two neutralino masses m_⁰2 and m_⁰1, leaving only a discrete 2-fold ambiguity for the slepton mass m. This remaining ambiguity can be easily resolved in a number of different ways: for example, by a single additional measurement of the kinematic endpoint of any one out of the many remaining 1-dimensional distributions at our disposal, or by exploring the correlations in the 2-dimensional distribution of m²_jℓn∪m²_jℓf versus m²_ℓℓ. We illustrate our method with two examples: the LM1 and LM6 CMS study points. An additional advantage of our method is the expected improvement in the accuracy of the SUSY mass determination, due to the multitude and variety of available measurements.

We investigate the high energy behavior of QCD for different surface topologies of color graphs. After a brief review of the planar limit (bootstrap and gluon reggeization) and of the cylinder topology (BFKL) we investigate the 3 → 3 scattering in the triple Regge limit which belongs to the pair-of-pants topology. We re-derive the triple Pomeron vertex function and show that it belongs to a specific set of graphs in color space which we identify as the analogue of the Mandelstam diagram.

We investigate the thermodynamics of non-relativistic and relativistic ideal gases on the spacetime with noncommutative fuzzy geometry. We first find that the heat capacities of the non-relativistic ideal boson and fermion on the fuzzy two-sphere have different values, contrast to that on the commutative geometry. We calculate the ``statistical interparticle potential'' therein and interprete this property as a result that the non-commutativity of the fuzzy sphere has an inclination to enhance the statistical ``attraction (repulsion) interparticle potential'' between boson (fermion). We also see that at high temperature the heat capacity approaches to zero. We next evaluate the heat capacities of the non-relativistic ideal boson and fermion on the product of the 1+D (with D=2,3) Minkowski spacetime by a fuzzy two-sphere and see that the fermion capacity could be a decreasing function of temperature in high-temperature limit, contrast to that always being an increasing function on the commutative geometry. Also, the boson and fermion heat capacities both approach to that on the 1+D Minkowski spacetime in high-temperature limit. We discuss these results and mention that the properties may be traced to the mechanism of ``thermal reduction of the fuzzy space''. We also investigate the same problems in the relativistic system with free Klein-Gordon field and Dirac field and find the similar properties.

Motivated by the Kerr-CFT conjecture, we investigate perturbations of the near-horizon extreme Kerr spacetime. The Teukolsky equation for a massless field of arbitrary spin is solved. Solutions fall into two classes: normal modes and traveling waves. Imposing suitable (outgoing) boundary conditions, we find that there are no unstable modes. The explicit form of metric perturbations is obtained using the Hertz potential formalism, and compared with the Kerr-CFT boundary conditions. The energy and angular momentum associated with scalar field and gravitational normal modes are calculated. The energy is positive in all cases. The behaviour of second order perturbations is discussed.

We study the ``fermionic billiards'', i.e. the chaotic dynamics of the gravitino, that arise in the near-spacelike-singularity limit of eleven-dimensional supergravity and of its dimensional truncations (notably four-dimensional simple supergravity). By exploiting the gravity-coset correspondence, we show that the billiard dynamics of the gravitino is described by a `spin extension' of the Weyl group of the hyperbolic Kac-Moody algebra E<sub>10</sub>. This spin extension is a discrete subgroup of (a spin covering of) the maximal compact subgroup K(E<sub>10</sub>) of E<sub>10</sub> that is generated by ten (simple-root-related) idempotent elements of order 8. The `super-billiard' that combines the bosonic and fermionic billiards is found to have a remarkably simple structure, which exhibits a striking analogy with a polarized photon propagating in the ten-dimensional Lorentzian Weyl chamber of E₁₀.

The Tevatron experiments have recently excluded a Standard Model Higgs boson in the mass range 160 GeV < m^H < 170 GeV at the 95% confidence level. This result is based on sophisticated analyses designed to maximize the ratio of accepted signal to background. In this paper we study the production of a Higgs boson of mass m^H = 160 GeV in the gg → H → WW → lνlν channel. We choose a set of cuts like those adopted in the experimental analysis and compare kinematical distributions of the final state leptons computed in NNLO QCD to lower-order calculations and to those obtained with the event generators PYTHIA, HERWIG and MC@NLO. We also show that the distribution of the output from an Artificial Neural Network obtained with the different tools does not show significant differences. However, the final acceptance computed with PYTHIA is smaller than those obtained at NNLO and with HERWIG and MC@NLO. We also investigate the impact of the underlying event and hadronization on our results.

We study the symmetries of pure = 2 supergravity in D = 4. As is known, this theory reduced on one Killing vector is characterised by a non-linearly realised symmetry SU(2,1) which is a non-split real form of SL(3,). We consider the BPS brane solutions of the theory preserving half of the supersymmetry and the action of SU(2,1) on them. Furthermore we provide evidence that the theory exhibits an underlying algebraic structure described by the Lorentzian Kac-Moody group SU(2,1)⁺⁺⁺. This evidence arises both from the correspondence between the bosonic space-time fields of = 2 supergravity in D = 4 and a one-parameter sigma-model based on the hyperbolic group SU(2,1)⁺⁺, as well as from the fact that the structure of BPS brane solutions is neatly encoded in SU(2,1)⁺⁺⁺. As a nice by-product of our analysis, we obtain a regular embedding of the Kac-Moody algebra (2,1)⁺⁺⁺ in ₁₁ based on brane physics.

We identify the leading finite-size (Lüscher-type) correction to the energy of open strings ending on maximal giant gravitons. In particular we obtain the leading finite size correction at weak 't Hooft coupling and in the planar limit to the energy of very short vacuum states. These results are shown to agree with certain 1, 2, 3 and 4-loop dual gauge theory perturbative calculations, which we also perform.

We use supersymmetric generalised unitarity to calculate supercoefficients of box functions in the expansion of scattering amplitudes in = 8 supergravity at one loop. Recent advances have presented tree-level amplitudes in = 8 supergravity in terms of sums of terms containing squares of colour-ordered Yang-Mills superamplitudes. We develop the consequences of these results for the structure of one-loop supercoefficients, recasting them as sums of squares of = 4 Yang-Mills expressions with certain coefficients inherited from the tree-level superamplitudes. This provides new expressions for all one-loop box coefficients in = 8 supergravity, which we check against known results in a number of cases.

We discuss what predictions can be made for one-loop superamplitudes in maximally supersymmetric Yang-Mills theory by using anomalous dual conformal symmetry. We show that the anomaly coefficient is a specific combination of two-mass hard and one-mass supercoefficients which appears in the supersymmetric on-shell recursion relations and equals the corresponding tree-level superamplitude. We discuss further novel relations among supercoefficients imposed by the remaining non-anomalous part of the symmetry. In particular, we find that all one-loop supercoefficients, except the four-mass box coefficients, can be expressed as linear combinations of three-mass box coefficients and a particular symmetric combination of two-mass hard coefficients. We check that our equations are explicitly satisfied in the case of one-loop n-point MHV and NMHV amplitudes. As a bonus, we prove the covariance of the NMHV superamplitudes at an arbitrary number of points, extending previous results at n ⩽ 9.

Starting from the action of two coincident non-BPS D9-branes, we investigate kink configurations of the {\rm U}(2) matrix tachyon field. We consider both Str and Tr prescriptions for the trace over gauge indices of the non-BPS action. Non-abelian tachyon condensation in the theory with Tr prescription, and the resulting fluctuations about the kink profile, are shown to give rise to a theory of two coincident BPS D8-branes. This is a natural non-abelian generalization of Sen's mechanism of tachyon condensation on a single non-BPS Dp-brane yielding a single BPS brane of codimesion one. By contrast, starting with the Str gauge trace prescription of the coincident non-BPS D9-brane action, such a generalization of Sen's mechanism appears problematic.

We study the supersymmetry enhancement of ABJM theory. Starting from a = 2 supersymmetric Chern-Simons matter theory with gauge group U(2) × U(2) which is a truncated version of the ABJM theory, we find by using the monopole operator that there is additional = 2 supersymmetry related to the gauge group. We show this additional supersymmetry can combine with = 6 supersymmetry of the original ABJM theory to an enhanced = 8 SUSY with gauge group U(2) × U(2) in the case k = 1,2. We also discuss the supersymmetry enhancement of the ABJM theory with U(N) × U(N) gauge group and find a condition which should be satisfied by the monopole operator.

We propose a set of consistent boundary conditions containing the spacelike warped black holes solutions of Topologically Massive Gravity. We prove that the corresponding asymptotic charges whose algebra consists in a Virasoro algebra and a current algebra are finite, integrable and conserved. A similar analysis is performed for the timelike warped AdS₃ spaces which contain a family of regular solitons. The energy of the boundary Virasoro excitations is positive while the current algebra leads to negative (for the spacelike warped case) and positive (for the timelike warped case) energy boundary excitations. We discuss the relationship with the Brown-Henneaux boundary conditions.

Dimensional reduction from 10 to 5 dimensions of the IIB supergravity Dirac equation written down on the AdS(5)xS(5) (+ self-dual 5-form) background provides the unambiguous values of bulk masses of Fermions in the effective 5D Randall and Sundrum theory. The use of ``untwisted" and twisted" (hep-ph/0012378) boundary conditions at the UV and IR ends of the warped space-time results in two towers of spectrum of Dirac equation: the ordinary one which is linear in spectral number and the ``twisted" one exponentially decreasing with growth of the 5-sphere spectral number. Taking into account the Fermion-5-form interaction (hep-th/9811106) gives the electron neutrino mass scale in the ``twisted" spectrum of Dirac equation without any reference to seesaw mechanism and heavy right neutrino. Profiles in extra space of the eigenfunctions of left and right ``neutrinos" drastically differ which results in the extremely small coupling of light right chiral spinor with ordinary matter.

We derive model-independent bounds on production and detection non-standard neutrino interactions (NSI). We find that the constraints for NSI parameters are around (10⁻²) to (10⁻¹). Furthermore, we review and update the constraints on matter NSI. We conclude that the bounds on production and detection NSI are generally one order of magnitude stronger than their matter counterparts.

This work considers the way that quantum loop effects modify the propagation of light in curved space. The calculation of the refractive index for scalar QED is reviewed and then extended for the first time to QED with spinor particles in the loop. It is shown how, in both cases, the low frequency phase velocity can be greater than c, as found originally by Drummond and Hathrell, but causality is respected in the sense that retarded Green functions vanish outside the lightcone. A ``phenomenology'' of the refractive index is then presented for black holes, FRW universes and gravitational waves. In some cases, some of the polarization states propagate with a refractive index having a negative imaginary part indicating a potential breakdown of the optical theorem in curved space and possible instabilities.

We discuss neutralino dark matter arising from supersymmetric models with extra inert Higgsinos and singlinos, where inert means that their scalar partners do not get vacuum expectation values. As an example, we consider the extended neutralino sector of the E₆SSM, which predicts three families of Higgs doublet pairs, plus three singlets, plus a Z', together with their fermionic superpartners. We show that the two families of inert doublet Higgsinos and singlinos predicted by this model provide an almost decoupled neutralino sector with a naturally light LSP which can account for the cold dark matter relic abundance independently of the rest of the model, providing that the ratio of the two usual Higgs doublets satisfies tan β < 2.

We consider scenarios with large flavour violating entries in the squark mass matrices focusing on the mixing between second and third generation squarks. These entries govern both, flavour violating low energy observables on the one hand and squark and gluino decays on the other hand. We first discuss the constraints on the parameter space due to the recent data on B mesons from theB factories and Tevatron. We then consider flavour violating squark and gluino decays and show that they can still be typically of order 10% despite the stringent constraints from low energy data. Finally we briefly comment on the impact for searches and parameter determinations at future collider experiments such as the upcoming LHC or a future International Linear Collider.

We consider a small extension of the standard model by adding two Majorana fermions; those are adjoint representations of the SU(2)_L and SU(3)_c gauge groups of the standard model. In this extension, the gauge coupling unification at an energy scale higher than 10¹⁵ GeV is realized when the masses of the triplet and the octet fermions are smaller than 10⁴ GeV and 10¹² GeV, respectively. We also show that an appropriate symmetry ensures a long lifetime of the neutral component of the triplet fermion whose thermal relic density naturally explains the observed dark matter density. The electron/positron excesses observed in recent cosmic-ray experiments can be also explained by the decay of the triplet fermion.

We extend the massless dipole formalism of Catani and Seymour, as well as its massive version as developed by Catani, Dittmaier, Seymour and Trocsanyi, to arbitrary helicity eigenstates of the external partons. We modify the real radiation subtraction terms only, the primary aim being an improved efficiency of the numerical Monte Carlo integration of this contribution as part of a complete next-to-leading order calculation. In consequence, our extension is only applicable to unpolarized scattering. Upon summation over the helicities of the emitter pairs, our formulae trivially reduce to their original form. We implement our extension within the framework of \textsc{Helac-Phegas}, and give some examples of results pertinent to recent studies of backgrounds for the LHC. The code is publicly available. Since the integrated dipole contributions do not require any modifications, we do not discuss them, but they are implemented in the software.

SU(3) gauge theory in the 2-index symmetric (sextet) and fundamental representations is considered in symmetric and periodic boxes. Using the overlap formulation in the quenched approximation it is shown that the topological charge obtained from the sextet index theorem always leads to an integer value and agrees with the charge obtained from the fundamental index theorem in the continuum. At larger lattice spacing configurations exist with fractional topological charge if the sextet index is used but these are lattice artifacts and the probability of finding such a configuration rapidly approaches zero. By considering the decomposition of the sextet representation with respect to an SU(2) subgroup it is shown that the SU(2) adjoint index theorem leads to integer charge as well. We conclude that the non-zero value of the bilinear gaugino condensate in = 1 super-Yang-Mills theory cannot be attributed to configurations with fractional topological charge once periodic boundary conditions are imposed.

Correlation functions of operators with a conformal dimension of O(N²) are not well approximated by the planar limit. The non-planar diagrams, which in the bulk spacetime correspond to string loop corrections, are enhanced by huge combinatorial factors. In this article we show how these loop corrections can be resummed. As a typical example of our results, in the half-BPS background of M maximal giant gravitons we find the usual 1/N expansion is replaced by a 1/(M+N) expansion. Further, we find that there is a simple exact relationship between amplitudes computed in the trivial background and amplitudes computed in the background of M maximal giant gravitons. Finally, we also find strong evidence for the BMN-type sectors suggested in arXiv:0801.4457. The decoupling limit of arXiv:0801.4457 captures the decoupled low energy world volume theory of the intersecting giant graviton system and this theory is weakly coupled even when the original = 4 super Yang-Mills theory is strongly coupled.

We explore the possibility of indirectly observing the effects of Z'-like particles with electroweak strength couplings in the Drell-Yan channel at the LHC with masses above the resonance direct search reach. We find that, mostly due to statistical limitations, this is very unlikely in almost all classes of models independently of the spin of the resonance. Not unexpectedly, the one possible exception to this general result is the case of degenerate Kaluza-Klein (KK) excitations of the photon and Z that occur in some extra-dimensional models. In this special case, the strong destructive interference with the Standard Model (SM) exchanges below the resonance mass leads to a well-known significant suppression of the cross section and thus increased sensitivity to this particular new physics scenario.

A new superconformal mechanics with OSp(4|2) symmetry is obtained by gauging the U(1) isometry of a superfield model. It is the one-particle case of the new = 4 super Calogero model recently proposed in arXiv:0812.4276 [hep-th]. Classical and quantum generators of the osp(4|2) superalgebra are constructed on physical states. As opposed to other realizations of = 4 superconformal algebras, all supertranslation generators are linear in the odd variables, similarly to the = 2 case. The bosonic sector of the component action is standard one-particle (dilatonic) conformal mechanics accompanied by an SU(2)/U(1) Wess-Zumino term, which gives rise to a fuzzy sphere upon quantization. The strength of the conformal potential is quantized.

We examine the minimal supergravity (mSUGRA) model under the assumption that the strong CP problem is solved by the Peccei-Quinn mechanism. In this case, the relic dark matter (DM) abundance consists of three components: i). cold axions, ii). warm axinos from neutralino decay, and iii). cold or warm thermally produced axinos. To sustain a high enough re-heat temperature (T_R ≳ 10⁶ GeV) for many baryogenesis mechanisms to function, we find that the bulk of DM should consist of cold axions, while the admixture of cold and warm axinos should be rather slight, with a very light axino of mass ∼ 100 keV. For mSUGRA with mainly axion cold DM (CDM), the most DM-preferred parameter space regions are precisely those which are least preferred in the case of neutralino DM. Thus, rather different SUSY signatures are expected at the LHC in the case of mSUGRA with mainly axion CDM, as compared to mSUGRA with neutralino CDM.

We present analytic expressions of all integrals required to complete the explicit evaluation of the real-virtual integrated counterterms needed to define a recently proposed subtraction scheme for jet cross sections at next-to-next-to-leading order in QCD. We use the Mellin-Barnes representation of these integrals in 4 − 2 dimensions to obtain the coefficients of their Laurent expansions around = 0. These coefficients are given by linear combinations of multidimensional Mellin-Barnes integrals. We compute the coefficients of such expansions in both numerically and analytically by complex integration over the Mellin-Barnes contours.

We study the thermodynamics and the small fluctuations of a linear dilaton black hole, in an S-dual version of the near-horizon limit of type IIB NS5 branes. The thermodynamical analysis shows that the black hole is in a Hagedorn phase, with marginal stability. The dynamical analysis confirms that the speed of sound of the dual theory vanishes and that there are no evident instabilities at the level of supergravity. We clarify the physical meaning of some singularities of the retarded correlator that were thought to lead to instabilities.

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb⁻¹. The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, Λ_eff, and the LPHD parameter, κ^ch, are extracted.

In this note, a procedure is developed to explicitly construct non-trivial F-theory lifts of perturbative IIB orientifold models on Calabi-Yau complete intersections in toric varieties. This procedure works on Calabi-Yau orientifolds where the involution coordinate can have arbitrary projective weight, as opposed to the well-known hypersurface cases where it has half the weight of the equation defining the CY threefold. This opens up the possibility of lifting more general setups, such as models that have O3-planes.

We present the first calculation of the next-to-leading-order electroweak corrections to W-boson + jet hadroproduction including leptonic W-boson decays. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are implemented in a flexible Monte Carlo code. Numerical results for cross sections and distributions of this Standard Model benchmark process are presented for the Tevatron and the LHC.

In a relativistic theory of quantum information, the possible presence of horizons is a complicating feature placing restrictions on the transmission and retrieval of information. We consider two inertial participants communicating via a noiseless qubit channel in the presence of a uniformly accelerated eavesdropper. Owing to the Unruh effect, the eavesdropper's view of any encoded information is noisy, a feature the two inertial participants can exploit to achieve perfectly secure quantum communication. We show that the associated private quantum capacity is equal to the entanglement-assisted quantum capacity for the channel to the eavesdropper's environment, which we evaluate for all accelerations.

We analyze SU(2) invariant half-BPS states of the 3d, = 8 or = 6 SCFT within the radial quantization of the ABJM theory [1], the theory proposed to describe N M2-branes in the R³ × ⁴/Z_k background. After studying the classical moduli space of these configurations, we explicitly construct a set of gauge invariant operators involving 't Hooft monopole operators corresponding to these states. We show there is a one-to-one correspondence between the two sets carrying R-charge J and that they are labeled by Young tableaux of J boxes with a maximum of N rows. Restricting the full path integral to this half-BPS sector of the theory, we show the latter is described in terms of N fermions in a 2d harmonic potential in the sector of vanishing angular momentum. The same classification, though in the N → ∞ limit, arise from the plane-wave (BMN) Matrix theory as well as the 11 dimensional LLM bubbling geometries [2], providing supportive evidence for the ABJM theory and/or the Matrix model.

We construct symmetries of the Chalmers-Siegel action describing self-dual Yang-Mills theory using a canonical transformation to a free theory. The symmetries form an infinite dimensional Lie algebra in the group algebra of isometries.

In this note, we discuss membrane scattering from the three dimensional N = 8 superconformal theory with SO(8) global symmetry constructed by Bagger-Lambert and Gustavsson. We discuss whether the one loop effective potential consistently reproduces the Newton potential of membranes moving in an eleven dimensional orbifold space.

By studying perturbations about the vacuum, we show that Hořava gravity suffers from two different strong coupling problems, extending all the way into the deep infra-red. The first of these is associated with the principle of detailed balance and explains why solutions to General Relativity are typically not recovered in models that preserve this structure. The second of these occurs even without detailed balance and is associated with the breaking of diffeomorphism invariance, required for anisotropic scaling in the UV. Since there is a reduced symmetry group there are additional degrees of freedom, which need not decouple in the infra-red. Indeed, we use the Stuckelberg trick to show that one of these extra modes become strongly coupled as the parameters approach their desired infra-red fixed point. Whilst we can evade the first strong coupling problem by breaking detailed balance, we cannot avoid the second, whatever the form of the potential. Therefore the original Hořava model, and its "phenomenologically viable" extensions do not have a perturbative General Relativity limit at any scale. Experiments which confirm the perturbative gravitational wave prediction of General Relativity, such as the cumulative shift of the periastron time of binary pulsars, will presumably rule out the theory.

A thorough analysis of stability and perturbativity bounds is performed in several versions of the two-Higgs doublet model, for both CP-conserving and spontaneously broken CP minima. LEP results further aid in establishing very strict constraints on the mass of the lighter Higgs particle.

Quantum entropy function is a proposal for computing the entropy associated with the horizon of a black hole in the extremal limit, and is related via AdS/CFT correspondence to the dimension of the Hilbert space in a dual quantum mechanics. We show that in = 4 supersymmetric string theories, quantum entropy function formalism naturally explains the origin of the subtle differences between the microscopic degeneracies of quarter BPS dyons carrying different torsion, i.e. different arithmetical properties. These arise from additional saddle points in the path integral — whose existence depends on the arithmetical properties of the black hole charges — constructed as freely acting orbifolds of the original AdS₂ × S² near horizon geometry. During this analysis we demonstrate that the quantum entropy function is insensitive to the details of the infrared cutoff used in the computation, and the details of the boundary terms added to the action. We also discuss the role of the asymptotic symmetries of AdS₂ in carrying out the path integral in the definition of quantum entropy function. Finally we show that even though quantum entropy function is expected to compute the absolute degeneracy in a given charge and angular momentum sector, it can also be used to compute the index. This can then be compared with the microscopic computation of the index.

We evaluate the planar two-loop QCD diagrams contributing to the leading color coefficient of the heavy-quark pair production cross section, in the quark-antiquark annihilation channel. We obtain the leading color coefficient in an analytic form, in terms of one- and two-dimensional harmonic polylogarithms of maximal weight 4. The result is valid for arbitrary values of the Mandelstam invariants s and t, and of the heavy-quark mass m. Our findings agree with previous analytic results in the small-mass limit and numerical results for the exact amplitude.

We calculate the pressure of massless ϕ⁴-theory to order g⁸log (g) at weak coupling. The contributions to the pressure arise from the hard momentum scale of order T and the soft momentum scale of order gT. Effective field theory methods and dimensional reduction are used to separate the contributions from the two momentum scales: The hard contribution can be calculated as a power series in g² using naive perturbation theory with bare propagators. The soft contribution can be calculated using an effective theory in three dimensions, whose coefficients are power series in g². This contribution is a power series in g starting at order g³. The calculation of the hard part to order g⁶ involves a complicated four-loop sum-integral that was recently calculated by Gynther, Laine, Schröder, Torrero, and Vuorinen. The calculation of the soft part requires calculating the mass parameter in the effective theory to order g⁶ and the evaluation of five-loop vacuum diagrams in three dimensions. This gives the free energy correct up to order g⁷. The coefficients of the effective theory satisfy a set of renormalization group equations that can be used to sum up leading and subleading logarithms of T/gT. We use the solutions to these equations to obtain a result for the free energy which is correct to order g⁸log (g). Finally, we investigate the convergence of the perturbative series.

We compute the spin-2 Kaluza-Klein modes around a warped product of AdS₄ and a seven-ellipsoid. This background with global G₂ symmetry is related to a U(N) × U(N) = 1 superconformal Chern-Simons matter theory with sixth order superpotential. The mass-squared in AdS₄ is quadratic in G₂ quantum number and KK excitation number. We determine the dimensions of spin-2 operators using the AdS/CFT correspondence. The connection to = 2 theory preserving SU(3) × U(1)_R is also discussed.

In 5-dimensional models with gauge-Higgs unification, the F-term vacuum expectation value of the radion provides, in close analogy to the Giudice-Masiero mechanism, a natural source for the μ and Bμ term. Both the leading order gauge theory lagrangian and the supersymmetric Chern-Simons term contain couplings to the radion superfield which can be used for this purpose. We analyse the basic features of this mechanism for μ term generation and provide an explicit example, based on a variation of the SU(6) gauge-Higgs unification model of Burdman and Nomura. This construction contains all the relevant features used in our generic analysis. More generally, we expect our mechanism to be relevant to many of the recently discussed orbifold GUT models derived from heterotic string theory. This provides an interesting way of testing high-scale physics via Higgs mass patterns accessible at the LHC.

We study a new kind of tunneling of particles through a barrier particular to quantum field theory. Here, the particles traverse the barrier by splitting into a virtual pair of particles of a different species which interacts only very weakly with the barrier and can therefore pass through it. Behind the barrier, the pair recombines into a particle of the original species. As an example, we discuss the case where photons split into a pair of minicharged particles. This process could be observed in experiments of the light-shining-through-a-wall type and may be used to search for minicharged particles in laboratory experiments.

We study various physical quantities associated with holographic s-wave superconductors as functions of the scaling dimensions of the dual condensates. A bulk scalar field with negative mass squared m², satisfying the Breitenlohner-Freedman stability bound and the unitarity bound, and allowed to vary in 0.5 unit intervals, were considered. We observe that all the physical quantities investigated are sensitive to the scaling dimensions of the dual condensates. For all the m², the characteristic lengths diverge at the critical temperature in agreement with the Ginzburg-Landau theory. The Ginzburg-Landau parameter, obtained from these length scales indicates that the holographic superconductors can be type I or type II depending on the charge and the scaling dimensions of the dual condensates. For a fixed charge, there exists a critical scaling dimension, above which a holographic superconductor is type I, below which it becomes a type II.

We study the correlators of a recently discovered family of BPS Wilson loops in = 4 supersymmetric U(N) Yang-Mills theory. When the contours lie on a two-sphere in the space-time, we propose a closed expression that is valid for all values of the coupling constant g and for any rank N, by exploiting the suspected relation with two-dimensional gauge theories. We check this formula perturbatively at order (g⁴) for two latitude Wilson loops and we show that, in the limit where one of the loops shrinks to a point, logarithmic corrections in the shrinking radius are absent at (g⁶). This last result strongly supports the validity of our general expression and suggests the existence of a peculiar protected local operator arising in the OPE of the Wilson loop. At strong coupling we compare our result to the string dual of the = 4 SYM correlator in the limit of large separation, presenting some preliminary evidence for the agreement.

By making an appropriate choice for gauge fixing kappa-symmetry we obtain a relatively simple form of the actions for a D = 11 superparticle in AdS₄ × S⁷/Z_k, and for a D0-brane, fundamental string and D2-branes in the AdS₄ × CP³ superbackground. They can be used to study various problems of string theory and the AdS₄/CFT₃ correspondence, especially in regions of the theory which are not reachable by the OSp(6|4)/U(3) × SO(1,3) supercoset sigma-model. In particular, we present a simple form of the gauge-fixed superstring action in AdS₄ × CP³ and briefly discuss issues of its T-dualization.

We note that the equations of relativistic hydrodynamics reduce to the incompressible Navier-Stokes equations in a particular scaling limit. In this limit boundary metric fluctuations of the underlying relativistic system turn into a forcing function identical to the action of a background electromagnetic field on the effectively charged fluid. We demonstrate that special conformal symmetries of the parent relativistic theory descend to `accelerated boost' symmetries of the Navier-Stokes equations, uncovering a conformal symmetry structure of these equations. Applying our scaling limit to holographically induced fluid dynamics, we find gravity dual descriptions of an arbitrary solution of the forced non-relativistic incompressible Navier-Stokes equations. In the holographic context we also find a simple forced steady state shear solution to the Navier-Stokes equations, and demonstrate that this solution turns unstable at high enough Reynolds numbers, indicating a possible eventual transition to turbulence.

We compute the one-loop QCD amplitudes for the processes HqQ and Hqgg, the latter restricted to the case of opposite-helicity gluons. Analytic expressions are presented for the color- and helicity-decomposed amplitudes. The coupling of the Higgs boson to gluons is treated by an effective interaction in the limit of large top quark mass. The Higgs field is split into a complex field ϕ and its complex conjugate ϕ^†. The split is useful because amplitudes involving ϕ have different analytic structure from those involving ϕ^†. We compute the cut-containing pieces of the amplitudes using generalized unitarity. The remaining rational parts are obtained by on-shell recursion. Our results for HqQ agree with previous semi-numerical computations. We also show how to convert existing semi-numerical results for the production of a scalar Higgs boson into analogous results for a pseudoscalar Higgs boson.

We study the dynamics of probe D7 flavor probe branes in the background of near extremal D5 branes. This model is a holographic dual to a gauge theory with spontaneous breaking of a U(N_f)_L × U(N_f)_R chiral symmetry. The spectrum of two such D7 embeddings, contains a single massive 4D meson coming from the world volume U(1) gauge field, the pion, and a single massive 4D scalar meson coming from fluctuations of the embedding of the brane. In addition, there are continuum five dimensional states due to the finite height of the effective potential in the radial direction. We investigate baryons in this model, and find that the size is stabilized due to the Chern-Simons term in the D7 world volume action. The model admits a Hagedorn temperature of 1/2πR where R is the radius parameter in the D5 branes metric. We investigate the pattern of chiral symmetry breaking in the deconfined phase as a function of the asymptotic separation of the branes L. We find that for πR/3 < L ⪅ 1.068R that chiral symmetry is restored, and that chiral symmetry is broken for L outside this window. We further argue that the solutions with L < π/3 are only classically stable, and in fact no D7 embedding exists with these boundary conditions.

The fully unintegrated, off-diagonal quark-quark correlator for a spin-1/2 hadron is parameterized in terms of so-called generalized parton correlation functions. Such objects, in particular, can be considered as mother distributions of generalized parton distributions on the one hand and transverse momentum dependent parton distributions on the other. Therefore, our study provides new, model-independent insights into the recently proposed nontrivial relations between generalized and transverse momentum dependent parton distributions. We find that none of these relations can be promoted to a model-independent status. As a by-product we obtain the first complete classification of generalized parton distributions beyond leading twist. The present paper is a natural extension of our previous corresponding analysis for spin-0 hadrons.

We analyze metastable supersymmetry breaking in 3D WZ models. We study the regime of validity of the perturbative computation for superpotentials with marginal and relevant couplings. Lifetime of the metastable states in presence of a triangular potential barrier is estimated.

We study the properties of walls of marginal stability for BPS decays in a class of = 2 theories. These theories arise in = 2 string compactifications obtained as freely acting orbifolds of = 4 theories, such theories include the STU model and the FHSV model. The cross sections of these walls for a generic decay in the axion-dilaton plane reduce to lines or circles. From the continuity properties of walls of marginal stability we show that central charges of BPS states do not vanish in the interior of the moduli space. Given a charge vector of a BPS state corresponding to a large black hole in these theories, we show that all walls of marginal stability intersect at the same point in the lower half of the axion-dilaton plane. We isolate a class of decays whose walls of marginal stability always lie in a region bounded by walls formed by decays to small black holes. This enables us to isolate a region in moduli space for which no decays occur within this class. We then study entropy enigma decays for such models and show that for generic values of the moduli, that is when moduli are of order one compared to the charges, entropy enigma decays do not occur in these models.

The addition of non-renormalizable terms involving the Higgs fields to the MSSM (BMSSM) ameliorates the little hierarchy problem of the MSSM. We analyze in detail the two main cosmological issues affected by the BMSSM: dark matter and baryogenesis. The regions for which the relic abundance of the LSP is consistent with WMAP and collider constraints are identified, showing that the bulk region and other previously excluded regions are now permitted. Requiring vacuum stability limits the allowed regions. Based on a two-loop finite temperature effective potential analysis, we show that the electroweak phase transition can be sufficiently first order in regions that for the MSSM are incompatible with the LEP Higgs mass bound, including parameter values of tan β≲5,m₁>m_t, m_Q < < TeV.

Motivated by the recent ``Cosmos Project" observation of dark-matter concentrations with no ordinary matter in the same place, we study the question of the existence of compact objects made of pure dark matter. We assume that the dark matter is neutralino, and compare its elastic and annihilation cross sections. We find that the two cross sections are of the same order of magnitude. This result has a straightforward and important consequence that neutralinos comprising a compact object can not achieve thermal equilibrium. To substantiate our arguments, by solving Oppenheimer-Volkoff equation we constructed a model of the star made of pure neutralinos. We explicitly showed that the condition for the thermal equilibrium supported by the Fermi pressure is never fulfilled inside the star. This neutralino state can not be described by the Fermi-Dirac distribution. Thus, a stable neutralino star, which is supported by the Fermi pressure, can not exist. We also estimated that a stable star can not contain more than a few percents of neutralinos, most of the mass must be in the form of the standard model particles.

We consider several hints for new physics involving CP-asymmetries in B-decays and interpret them in terms of generic contributions to effective Wilson coefficients. The effects we focus on are: the differences in the fitted value of sin 2β versus the ones directly measured via the time dependent CP asymmetries in B → J/ψK or via B → (ϕ,η')K; the difference between the direct CP asymmetries in B⁻ → K⁻π⁰ and ⁰ → K⁻π⁺ and the ≈ 2.2σ indications for the CP-asymmetry in B_s → J/ψϕ. To alleviate concerns regarding the disagreement between inclusive and exclusive V_ub, we show that our results hold even without the inclusion of V_ub in the analysis. We find that no matter what kind of new physics (NP) is invoked to explain these effects, its effective scale is bounded from above from a few hundred GeV to a few TeV depending on specific assumptions regarding the type of new physics. The only exception to this is when the NP contribution is assumed to reside entirely in LR operators in K mixing, then the scale of NP can be as high as around 24 TeV; however, this case cannot account for CP asymmetry in B_s → J/ψϕ or a difference in sin 2β from penguin modes compared to that from J/ψK or for that matter the large difference seen between direct CP asymmetries in K⁻π⁺ and in K⁻π⁰.

We analyze BPS equations for string-like configurations derived from the M5-brane worldvolume action with a Nambu-Poisson structure constructed in ref. [1, 2]. We solve the BPS equations up to the first order in the parameter g which characterizes the strength of the Nambu-Poisson bracket. We compare our solutions to previously constructed BPS string solitons in the conventional description of M5-brane in a constant three-form background via Seiberg-Witten map, and find agreement.

We present results for the next-to-leading order QCD corrections to the production and semi-leptonic decays of a top quark pair in hadron collisions, retaining all spin correlations. To evaluate the virtual corrections, we employ generalized D-dimensional unitarity. The computation is implemented in a numerical program which allows detailed studies of t-related observables at the Tevatron and the LHC.

We prove that the NS cubic superstring field theories are classically equivalent, regardless of the choice of Y₋₂ in their definition, and illustrate it by an explicit evaluation of the action of Erler's solution. We then turn to examine this solution. First, we explain that its cohomology is trivial also in the Ramond sector. Then, we show that the boundary state corresponding to it is identically zero. We conclude that this solution is indeed a closed string vacuum solution despite the absence of a tachyon field on the BPS D-brane.

Generalizing the work by Cherkis and Schwarz [1] where the bosonic part of the heterotic action was worked out with the novel introduction of the chiral bosons associated with the current algebra, we carry out the double dimensional reduction of supersymmetric M5 brane on K3 to obtain the supersymmetric action of heterotic string in 7-dimensional flat space-time. Motivated by this result, we propose the supersymmetric heterotic action in 10-dimensional flat space-time where the chiral bosons are introduced in similar way. We explicitly verify the κ-symmetry of the proposed action.

We analyze constraints for embedding local SU(5) F-theory GUTs into consistent compactifications and construct explicit three-generation models based on the geometry of [1]. The key tool for studying constraints in this problem when there is an underlying E₈ structure is the spectral cover, which encodes all of the symmetries that fix the allowed couplings in the superpotential, as well as the consistent, supersymmetric G-fluxes. Imposing phenomenological requirements such as the existence of three generations, top and bottom Yukawa couplings, good flavor structure and absence of exotics and of a tree-level μ-term, we derive stringent constraints on the allowed spectral covers. The resulting spectral covers are in conflict with the neutrino scenarios that have been studied in local F-theory models unless we allow for the possibility of additional charged fields, perhaps playing the role of gauge messengers, that do not comprise complete GUT multiplets. Quite remarkably, the existence of additional incomplete GUT multiplets below the GUT scale is necessary for consistency with gauge coupling "unification", as their effect can precisely cancel that of the internal hypercharge flux, which distorts the gauge couplings already at M_GUT.

We investigate the recently proposed Kerr/CFT correspondence in the context of heterotic string theory. The Kerr/CFT correspondence states that the near-horizon states of an extremal four (or higher) dimensional black hole could be identified with a certain chiral conformal field theory under the conjecture that the central charges from the non-gravitational fields vanish. The corresponding Virasoro algebra is generated by a class of diffeomorphisms which preserves the appropriate boundary conditions on the near-horizon geometry. To understand the chiral conformal field theory, we consider the class of extremal Kerr-Sen black hole (that contains three non-gravitational fields) as a class of solutions in the low energy limit (effective field theory) of heterotic string theory. We derive the expression of the conserved charges for the extremal Kerr-Sen solutions that contain dilaton, abelian gauge filed and antisymmetric tensor filed. We confirm and extend the validity of the conjecture (that the central charges from the non-gravitational fields vanish) for theories including antisymmetric tensor fields. We combine the calculated central charges with the expected form of the temperature using the Cardy formula to obtain the entropy of the extremal black hole microscopically; in agreement with the macroscopic Bekenstein-Hawking entropy of the extremal black hole.

We offer some thoughts regarding the space of string fields. We suggest that this space should be identified as the odd component of a star-algebra and focus among other issues on the role of the mid-point. We argue that theories with mid-point insertions in the action, such as the modified cubic theory can be well behaved, even if this mid-point insertion has a non-trivial kernel. We then discuss the recent proposal by Berkovits and Siegel of a non-minimal superstring field theory. In this theory the action contains a mid-point insertion of a non-zero conformal weight. We show that, while this is a-priori a problem, it might be possible (in the NS sector) to make sense out of this theory by regularizing it. A cleaner resolution of the problem is to extend the non-minimal sector in a way that allows a zero-weight mid-point insertion with the desired properties. We also study the generalisation of the theory to the NS- sector and explain the problems with defining the Ramond sectors. We show that the non-minimal theory supports all the known solutions of the standard modified cubic superstring field theory, including the GSO+ vacuum solution. The properties of the solutions carry over to the non-minimal theory. In particular, the vacuum solution has the correct tension and cohomology.

We propose that the solution to the cosmological vacuum energy puzzle may come from the infrared sector of the effective theory of gravity, where the impact of the trace anomaly is of upmost relevance. We proceed by introducing two auxiliary fields, which are capable of describing a diversity of quantum states via specification of their macroscopic (IR) boundary conditions, in contrast to ultraviolet quantum effects. Our investigation aims at finding a realistic cosmological solution which interprets the observed cosmological constant as a well defined deficit in the zero point energy density of the Universe. The energy density arises from a phase transition, which alters the properties of the quantum ground state. We explicitly formulate low energy gravity as an effective field theory with a precise definition of the ``point of normalization" as the point at which the ``renormalized cosmological constant" is set to zero in the Minkowski vacuum, in which the Einstein equations are automatically satisfied as the Ricci tensor identically vanishes. With this definition the effective QFT of gravity has a predictive power. In particular, it must predict the evolution of the system in any nontrivial geometry, including the vacuum energy behaviour as a function of infrared, rather than ultraviolet, input parameters.

Two-Higgs-doublet models (2HDM) are simple extensions of the Standard Model (SM) where the scalar sector is enlarged by adding a weak doublet. As a result, the Higgs potential depends in general on several free parameters which have to be carefully chosen to give predictions consistent with the current precision data. We consider a 2HDM invariant under a twisted custodial symmetry and depending only on three extra parameters beyond the SM ones. This model can naturally feature an inverted mass spectrum with a light pseudoscalar state and a heavy SM-like Higgs boson. We thoroughly analyze direct and indirect constraints and present a few unconventional though promising signatures at the LHC.

We study the potential of a Neutrino Factory in constraining the parameter space of a scheme with one sterile neutrino separated from three active ones by an O(1) eV² mass-squared difference. We present approximated analytic expressions for the oscillation probabilities, showing that the greatest sensitivity to sterile neutrinos at a Neutrino Factory can be achieved using the ν_μ → ν_μ and the ν_μ → ν_τ oscillations. We have studied two setups: a Neutrino Factory with 50 GeV (20 GeV) stored muons, with two detectors of the Hybrid-MIND type (a magnetized ECC next to a magnetized iron calorimeter), located at L = 3000, 7500 km (L = 4000, 7500 km) from the source. Four channels have been used: ν_e → ν_μ,ν_τ; ν_μ → ν_μ,ν_τ. The relevant backgrounds, efficiencies and systematic errors have been taken into account, and we have discussed dependence of the sensitivities on the systematic errors. We have found that the 50 GeV (20 GeV) setup can constrain sin² 2θ^(4fam)₁₃ ⩽ 7 × 10⁻⁵ (2 × 10⁻⁴); θ₃₄ ⩽ 12° (14°); and θ₂₄ ⩽ 7.5° (8°). Our results hold for any value of Δm²_SBL≳0.1 eV². Eventually we have shown that, if a positive signal is found, the proposed setup is able to measure simultaneously θ₃₄ and δ₃ with a precision of few degrees and few tens of degrees, respectively, solving the so-called "intrinsic" and "sign degeneracies". Combination of ν_μ disappearance and of the ν_μ → ν_τ channel, that will be called "the discovery channel'', at the two baselines is able to measure at 99% CL a new CP-violating phase δ₃ for sin² 2θ₃₄ ⩾ 0.06.

We study the local dynamics of an unoriented ₅-quiver theory of GUT kind with gauge group U(5) and chiral matter. At strong coupling the non-perturbative dynamics is described in terms of baryon and meson variables satisfying a quantum deformed constraint. We compute the effective superpotential of the theory and show that it admits a line of supersymmetric vacua for vanishing FI terms and a phase where supersymmetry is dynamically broken via gaugino condensation for a non-vanishing FI term.

We study all possible deformations of the Maxwell algebra. In D = d+1≠3 dimensions there is only one-parameter deformation. The deformed algebra is isomorphic to so(d+1,1)⊕so(d,1) or to so(d,2)⊕so(d,1) depending on the signs of the deformation parameter. We construct in the dS(AdS) space a model of massive particle interacting with Abelian vector field via non-local Lorentz force. In D = 2+1 the deformations depend on two parameters b and k. We construct a phase diagram, with two parts of the (b,k) plane with so(3,1)⊕so(2,1) and so(2,2)⊕so(2,1) algebras separated by a critical curve along which the algebra is isomorphic to Iso(2,1)⊕so(2,1). We introduce in D = 2+1 the Volkov-Akulov type model for a Abelian Goldstone-Nambu vector field described by a non-linear action containing as its bilinear term the free Chern-Simons Lagrangean.

We describe the structure of the vacuum states of quiver gauge theories obtained via dimensional reduction over homogeneous spaces, in the explicit example of SU(3)-equivariant dimensional reduction of Yang-Mills-Dirac theory on manifolds of the form M × P². We pay particular attention to the role of topology of background gauge fields on the internal coset spaces, in this case U(1) magnetic monopoles and SU(2) instantons on P². The reduction of Yang-Mills theory induces a quiver gauge theory involving coupled Yang-Mills-Higgs systems on M with a Higgs potential leading to dynamical symmetry breaking. The criterion for a ground state of the Higgs potential can be written as the vanishing of a non-abelian Yang-Mills flux on the quiver diagram, regarded as a lattice with group elements attached to the links. The reduction of SU(3)-symmetric fermions yields Dirac fermions on M transforming under the low-energy gauge group with Yukawa couplings. The fermionic zero modes on P² yield exactly massless chiral fermions on M, though there is a unique choice of spin^c structure on P² for which some of the zero modes can acquire masses through Yukawa interactions. We work out the spontaneous symmetry breaking patterns and determine the complete physical particle spectrum in a number of explicit examples, some of which possess quantum number assignments qualitatively analogous to the manner in which vector bosons, quarks and leptons acquire masses in the standard model.

Heavy neutral Higgs boson production and decay into neutralino and chargino pairs is studied at the Large Hadron Collider in the context of the minimal supersymmetric standard model. Higgs boson decays into the heavier neutralino and chargino states, i.e., H⁰,A⁰→₂⁰₃⁰, ₂⁰₄⁰, ₃⁰₃⁰, ₃⁰₄⁰, ₄⁰₄⁰ as well as H⁰,A⁰→₁^±₂^∓,₂⁺₂⁻ (all leading to four-lepton plus missing transverse energy final states), is found to improve the possibilities of discovering such Higgs states beyond those previously identified by considering H⁰,A⁰→₂⁰₂⁰ decays only. In particular, H⁰,A⁰ bosons with quite heavy masses, approaching ∼ 800 GeV in the so-called `decoupling region' where no clear SM signatures for the heavier MSSM Higgs bosons are known to exist, can now be discerned, for suitable but not particularly restrictive configurations of the low energy supersymmetric parameters. The high M_A discovery reach for the H⁰ and A⁰may thus be greatly extended. Full event-generator level simulations, including realistic detector effects and analyses of all significant backgrounds, are performed to delineate the potential H⁰,A⁰ discovery regions. The wedgebox plot technique is also utilized to further analyze the 4ℓ plus missing transverse energy signal and background events. This study marks the first thorough and reasonably complete analysis of this important class of MSSM Higgs boson signature modes. In fact, this is the first time discovery regions including all possible neutralino and chargino decay modes of the Higgs bosons have ever been mapped out.

We present a determination of the strong coupling constant from a fit of QCD predictions for six event-shape variables, calculated at next-to-next-to-leading order (NNLO) and matched to resummation in the next-to-leading-logarithmic approximation (NLLA). These event shapes have been measured in e⁺e⁻ annihilations at LEP, where the data we use have been collected by the ALEPH detector at centre-of-mass energies between 91 and 206 GeV. Compared to purely fixed order NNLO fits, we observe that the central fit values are hardly affected, but the systematic uncertainty is larger because the NLLA part re-introduces relatively large uncertainties from scale variations. By combining the results for six event-shape variables and eight centre-of-mass energies, we find

α_s(M_Z) = 0.1224 ± 0.0009 (stat) ± 0.0009 (exp) ± 0.0012 (had) ± 0.0035 (theo),

which improves previously published measurements at NLO+NLLA. We also carry out a detailed investigation of hadronisation corrections, using a large set of Monte Carlo generator predictions.

In this work we study the production and decay of two CP-even Higgs bosons in the general CP-conserving two-Higgs doublet model at the LHC. We also study the limiting case of the decoupling scenario. For each Yukawa version of the model, we look for the region of the parameter space where a signal would be seen at the LHC. Taking into account theoretical and experimental constraints on the two Higgs doublet model parameters, we show that the cross section can be two orders of magnitude above the corresponding Standard Model cross section. We have also studied in detail the decay profile of the Higgs bosons and showed that interesting signatures may emerge for some particular values of the parameters. There are scenarios where some of the triple Higgs couplings could be measured.

We study the spectrum of one single magnon in the superconformal β-deformed = 4 SYM theory in the planar limit. We compute the anomalous dimensions of one-impurity operators _1,L = tr (ϕZ^L−1), including wrapping contributions at their critical order L.

We study the = 2 supersymmetric Chern-Simons quiver gauge theory recently introduced in arXiv:0809.3237 to describe M2-branes on a cone over the well-known Sasaki-Einstein manifoldQ^1,1,1. For Chern-Simons levels (k,k,−k,−k) we argue that this theory is dual to AdS₄ × Q^1,1,1/_k. We derive the _k orbifold action and show that it preserves geometrical symmetry U(1)_R × SU(2) × U(1), in agreement with the symmetry of the gauge theory. We analyze the simplest gauge invariant chiral operators, and show that they match Kaluza-Klein harmonics on AdS₄ × Q^1,1,1/_k. This provides a test of the gauge theory, and in particular of its sextic superpotential which plays an important role in restricting the spectrum of chiral operators. We proceed to study other quiver gauge theories corresponding to more complicated orbifolds ofQ^1,1,1. In particular, we propose two U(N)⁴Chern-Simons gauge theories whose quiver diagrams are the same as in the 4d theories describing D3-branes on a complex cone over F₀, a ₂ orbifold of the conifold (in 4d the two quivers are related by the Seiberg duality). The manifest symmetry of these gauge theories is U(1)_R × SU(2) × SU(2). We argue that these gauge theories at levels (k,k,−k,−k) are dual toAdS₄ × Q^2,2,2/_k. We exhibit calculations of the moduli space and of the chiral operator spectrum which provide support for this conjecture. We also briefly discuss a similar correspondence for AdS₄ × M^3,2/_k. Finally, we discuss resolutions of the cones and their dual gauge theories.

We amalgamate the many experimental limits on the ab coupling of a light CP-odd Higgs boson, a, including model-dependence coming from the ratio of the at to the ab coupling. We then employ these limits to analyze the extent to which a light a can make a significant contribution to the discrepancy, Δa_μ, between the experimentally observed a_μ and that predicted by the standard model. In a ``model-independent'' framework and in the context of a general two-Higgs-doublet model this is a significant possibility. In contrast, the minimal supersymmetric model is too strongly constrained (after combining experimental and theoretical input) to allow a CP-odd-a explanation of Δa_μ. The next-to-minimal supersymmetric model allows more freedom and the light a of the model could explain the full Δa_μ if 9.2 GeV < m_a < 12 GeV, or contribute substantially for larger m_a, if tan β is large.

We consider the case of bulk photons in a Lorentz violating brane background, with an asymmetric warping between space and time warp factors. A perturbative analysis, in a previous work, gave an energy dependent phase (or group) velocity of light: V_ph(ω) = V_ph(0)−C_Gω² (C_G > 0), which was derived up to second order of time independent perturbation theory. In this paper, we go beyond the perturbative result and we study the nonperturbative behavior of the phase velocity for larger energies, by solving numerically an eigenvalue problem for the wave function of the zero mode (4D photon). In particular we see that V_ph(ω) is in general a monotonically decreasing function which tends asymptotically to a final value V_ph(∞). We compare with the results of perturbation theory and we obtain a very good agreement in the range of small energies. We also present a wave function analysis and we see that in the nonperturbative sector of the theory (very high energies), the zero mode and the massive KK modes tend to decouple from matter localized on the TeV brane.

We construct a family of elliptically fibered Calabi-Yau four-folds Y₄ for F-theory compactifications that realize SU(5) GUTs in the low-energy limit. The three-fold base X₃ of these fibrations is almost Fano and satisfies the topological criteria required to ensure that the U(1)_Y gauge boson remains massless, while allowing a decoupling of GUT and Planck scale physics. We study generic features of these models and the ability to engineer three chiral generations of MSSM matter. Finally, we demonstrate that it is relatively easy to implement the topological conditions required to reproduce certain successful features of local F-theory models, such as the emergence of flavor hierarchies.

Non-relativistic ABJM theory is defined by Galilean limit of mass-deformed = 6 Chern-Simons theory. Holographic string theory dual to the theory is not known yet. To understand features candidate gravity dual might exhibit, we examine local and nonlocal physical observables and their correlations in the non-relativistic ABJM theory. We show that gauge invariant local observables correspond to zero-norm states and that correlation functions among them are trivial. We also show that a particular class of nonlocal observables, Wilson loops, are topological in the sense that their correlation functions coincide with those of pure Chern-Simons theory. We argue that the theory is nevertheless physical and illustrate several physical observables whose correlation functions are nontrivial. We also study quantum aspects. We show that Chern-Simons level is finitely renormalized and that dilatation operator is trivial at planar limit. These results all point to string scale geometry of gravity dual and to intriguing topological and tensionless nature of dual string or M theory defined on it.

Spontaneous loss of charge by charged black holes by means of pair-creation of charged Dirac particles is considered. We provide three examples of exact calculations for the spontaneous discharge process for 4D charged black holes by considering the process on three special non-rotating de Sitter black hole backgrounds, which allow to bring back the problem to a Kaluza-Klein reduction. Both the zeta-function approach and the transmission coefficient approach are taken into account. A comparison between the two methods is also provided, as well as a comparison with WKB results. In the case of non-zero temperature of the geometric background, we also discuss thermal effects on the discharge process.

We consider a massless, minimally coupled scalar field propagating through the geometry of a black 3-brane in an asymptotically AdS₅ × S⁵ space. The wave equation for modes traveling purely in the holographic direction reduces to a Heun equation and the corresponding greybody factor is obtained numerically. Approximations valid in the low- and high-frequency regimes are also obtained analytically. The greybody factor is then used to determine the rate of evaporation of these large black holes in the context of the evaporon model proposed in [13]. This setting represents the evolution of a black hole under Hawking evaporation with a known CFT dual description and is therefore unitary. Information must then be preserved under this evaporation process.

We analyze the problem of the hierarchy of masses and mixings in orientifold realizations of the Standard Model. We find bottom-up brane configurations that can generate such hierarchies.

We construct new solutions of the Einstein equations with negative cosmological constant in five spacetime dimensions. They smoothly emerge as deformations of the known AdS₅ black strings. The first type of configurations can be viewed as the d = 4 Taub-NUT-AdS solutions uplifted to five dimensions, in the presence of a negative cosmological constant. We argue that these solutions would provide the gravity dual for a = 4 super-Yang-Mills theory formulated in a d = 4 homogeneous Gödel-type spacetime background. A different deformation of the AdS₅ black strings leads to squashed AdS black holes and their topological generalizations. In this case, the conformal infinity is the product of time and a circle-fibration over a base space that is a two-dimensional Einstein space.

We study the process of inhomogeneous tachyon condensation in an intersecting D1- and anti-D1-brane system using an effective tachyon DBI action. By switching to the Hamiltonian formalism, we numerically solve for the dynamical evolution of the system at a small intersection angle. We find that the decay proceeds indefinitely and resembles the action of two zippers moving away from the intersection point at the speed of light, zipping the branes together and leaving inhomogeneous tachyon matter behind. We also discuss the range of validity of our analysis and discuss the relation of the D1-anti-D1 description of the system to one in terms of an intersecting D1-D1-brane pair.

The projective superspace formulation for four-dimensional = 2 matter-coupled supergravity presented in arXiv:0805.4683 makes use of the variant superspace realization for the = 2 Weyl multiplet in which the structure group is SL(2,) × SU(2) and the super-Weyl transformations are generated by a covariantly chiral parameter. An extension to Howe's realization of = 2 conformal supergravity in which the tangent space group is SL(2,) × U(2) and the super-Weyl transformations are generated by a real unconstrained parameter was briefly sketched. Here we give the explicit details of the extension.

We study a new contraction of a d+1 dimensional relativistic conformal algebra where n+1 directions remain unchanged. For n = 0,1 the resultant algebras admit infinite dimensional extension containing one and two copies of Virasoro algebra, respectively. For n>1 the obtained algebra is finite dimensional containing an so(2,n+1) subalgebra. The gravity dual is provided by taking a Newton-Cartan like limit of the Einstein's equations of AdS space which singles out an AdS_n+2 spacetime. The infinite dimensional extension of n = 0,1 cases may be understood from the fact that the dual gravities contain AdS₂ and AdS₃ factor, respectively. We also explore how the AdS/CFT correspondence works for this case where we see that the main role is playing by AdS_n+2 base geometry.

Recently proposed Horava-Lifshitz gravity promises a UV completion of Einstein's theory by sacrificing general covariance at short distances and introducing anisotropic spacetime scaling. Here we present a dyonic solution by coupling this theory to a vector field and we discuss some properties of solution.

We study viscous hydrodynamics of hot conformal field theory plasma with multiple/non-Abelian symmetries in the framework of AdS/CFT correspondence, using a recently proposed method of directly solving bulk gravity in derivative expansion of local plasma parameters. Our motivation is to better describe the real QCD plasma produced at RHIC, incorporating its U(1)^N_f flavor symmetry as well as SU(2)_I non-Abelian iso-spin symmetry. As concrete examples, we choose to study the STU model for multiple U(1)³ symmetries, which is a sub-sector of 5D N=4 gauged SUGRA dual to N=4 Super Yang-Mills theory, capturing Cartan U(1)³ dynamics inside the full R-symmetry. For SU(2), we analyze the minimal 4D N=3 gauged SUGRA whose bosonic action is simply an Einstein-Yang-Mills system, which corresponds to SU(2) R-symmetry dynamics on M2-branes at a Hyper-Kahler cone. By generalizing the bosonic action to arbitrary dimensions and Lie groups, we present our analysis and results for any non-Abelian plasma in arbitrary dimensions.

In our five-dimensional cosmological model, we investigate the role of a Lorentz violating vector ``æther" field on the moduli stabilization mechanism. We consider the case of a space-like æther field on a compact circle with Maxwell-type kinetic term. The Casimir energy of certain combinations of massless and massive bulk fields generates a stabilizing potential for the radius of the compact direction while driving the accelerated expansion in the non-compact directions. It is shown that the æther field can reduce the influence of the Casimir force and slow down the oscillation of the radion field. This property proves crucial to the stability of the extra dimension in the universe where non-relativistic matter is present. We speculate that this scenario might reveal a hidden connection between the dimensionality of spacetime and the spontaneous breaking of Lorentz symmetry.

We establish the precise correspondence between Type-IIA flux compactifications preserving an exact or spontaneously broken = 4 supersymmetry in four dimensions, and gaugings of their effective = 4 supergravities. We exhibit the explicit map between fluxes and Bianchi identities in the higher-dimensional theory and generalized structure constants and Jacobi identities in the reduced theory, also detailing the origin of gauge groups embedded at angles in the duality group. We present AdS₄ solutions of the massive Type-IIA theory with spontaneous breaking to = 1, at small string coupling and large volume, and discuss their dual CFT₃.

We analyze various models with an extra U(1) gauge symmetry in addition to the Standard Model (SM) gauge group at low energies, and impose limits on the mass of the neutral Z' boson, M_Z', predicted in all such models, and on the Z−Z' mixing angle, θ_ZZ'. The precision electroweak (EW) data strongly constrain θ_ZZ' to very small values and for most models we find lower limits on M_Z' of (1TeV). In one case we obtain a somewhat better fit than in the SM (although this is only marginally statistically significant) and here we find a weak upper limit at the 90% C.L.

We study causality violation in holographic hydrodynamics in the gauge theory/string theory correspondence, focussing on Gauss-Bonnet gravity. The value of the Gauss-Bonnet coupling is related to the difference between the central charges of the dual conformal gauge theory. We show that, when this difference is sufficiently large, causality is violated both in the second-order truncated theory of hydrodynamics, as well as in the exact theory. We find that the latter provides more stringent constraints, which match precisely those appearing in the CFT analysis of Hofman and Maldacena.

We study the structure of the phase space in Hořava-Lifshitz theory. With the constraints derived from the action, the phase space is described by five fields, thus there is a lack of canonical structure. The Poisson brackets of the Hamiltonian density do not form a closed structure, resulting in many new constraints. Taking these new constraints into account, it appears that there is no degree of freedom left, or the phase space is reduced to one with an odd number of fields.

We study the consequences of an extension of the standard model containing an invisible extra gauge group under which the SM particles are neutral. We show that effective operators, generated by loops of heavy chiral fermions charged under both gauge groups and connecting the new gauge sector to the Standard Model, can give rise to a viable dark matter candidate. Its annihilations produce clean visible signals through a gamma-ray line. This would be a smoking gun signature of such models observable by actual experiments.

In this work we further extend the investigation of holographic gauge theories in external magnetic fields, continuing earlier work. We study the phenomenon of magnetic catalysis of mass generation in 1+3 and 1+2 dimensions, using D3/D7- and D3/D5-brane systems, respectively. We obtain the low energy effective actions of the corresponding pseudo Goldstone bosons and study their dispersion relations. The D3/D7 system exhibits the usual Gell-Mann–Oakes–Renner (GMOR) relation and a relativistic dispersion relation, while the D3/D5 system exhibits a quadratic non-relativistic dispersion relation and a modified linear GMOR relation. The low energy effective action of the D3/D5 system is related to that describing magnon excitations in a ferromagnet. We also study properties of general Dp/Dq systems in an external magnetic field and verify the universality of the magnetic catalysis of dynamical symmetry breaking.

We present an exact solution for a black hole localized near an infrared wall in four-dimensional anti-deSitter space. By computing the holographic stress tensor we show that the CFT dual of the black hole is a 2+1-dimensional ball (i.e., a disk) of plasma at finite temperature, surrounded by vacuum. This confirms some earlier conjectures about plasma balls in AdS/CFT. We also estimate the value of the surface tension for the ball. The solution displays a number of peculiarities, most notably a non-trivial curvature of the boundary geometry, as well as other properties associated to the vanishing deconfinement temperature of the set up. We discuss how these features are related to specific physics at the infrared and ultraviolet boundaries for this solution, and should not be generic properties of plasma balls.

Supersymmetric Gauge-Higgs Unification is a well-motivated new physics scenario, both in heterotic model building and from the perspective of higher-dimensional Grand Unified Theories. When combined with radion mediated supersymmetry breaking, it allows for very specific predictions concerning the high-scale parameters of the MSSM. Using an appropriately modified version of a standard RGE evolution code (SuSpect), we derive low-scale predictions which can be tested at the LHC. The phenomenological success of our setting depends crucially on the 5d Chern-Simons term, which has not been used in previous, less encouraging studies of gauge-Higgs unification in supersymmetry.

Strongly-coupled fermionic systems can support a variety of low-energy phenomena, giving rise to collective condensation, symmetry breaking and a rich phase structure. We explore the potential of worldline Monte Carlo methods for analyzing the effective action of fermionic systems at large flavor number N_f, using the Gross-Neveu model as an example. Since the worldline Monte Carlo approach does not require a discretized spacetime, fermion doubling problems are absent, and chiral symmetry can manifestly be maintained. As a particular advantage, fluctuations in general inhomogeneous condensates can conveniently be dealt with analytically or numerically, while the renormalization can always be uniquely performed analytically. We also critically examine the limitations of a straightforward implementation of the algorithms, identifying potential convergence problems in the presence of fermionic zero modes as well as in the high-density region.

If we find a light Higgs boson at the LHC, there should be many observable channels which we can exploit to measure the relevant parameters in the Higgs sector. We use the SFitter framework to map these measurements on the parameter space of a general weak-scale effective theory with a light Higgs state of mass 120 GeV. Our analysis benefits from the parameter determination tools and the error treatment used in new-physics searches, to study individual parameters and their error bars as well as parameter correlations.

Motivated by the sign problem in several systems, we have developed a geometric simulation algorithm based on the strong coupling expansion which can be applied to abelian pure gauge models. We have studied the algorithm in the U(1) model in 3 and 4 dimensions, and seen that it is practical and is similarly efficient to the standard heat-bath algorithm, but without the ergodicity problems which comes from the presence of vortices. We have also applied the algorithm to the Ising gauge model at the critical point, and we find hints of a better asymptotic behaviour of the autocorrelation time, which therefore suggests the possibility of a smaller dynamical critical exponent with respect to the standard heat-bath algorithm.

Using the AdS/CFT correspondence, we calculate the polarized structure functions in strongly coupled = 4 supersymmetric Yang-Mills theory deformed in the infrared. We find that the flavor singlet contribution to the g₁ structure function is vanishingly small, while the flavor non-singlet contribution shows the Regge behavior at small–x with an intercept slightly less than 1. We explicitly check that the latter satisfies the moment sum rule. We discuss the `spin crisis' problem and suggest that at strong coupling the spin of a hadron entirely comes from the orbital angular momentum.

In both Yang-Mills theories and sigma models, instantons are endowed with degrees of freedom associated to their scale size and orientation. It has long been conjectured that these degrees of freedom have a dual interpretation as the positions of partonic constituents of the instanton. These conjectures are usually framed in d = 3+1 and d = 1+1 dimensions respectively where the partons are supposed to be responsible for confinement and other strong coupling phenomena. We revisit this partonic interpretation of instantons in the context of d = 4+1 and d = 2+1 dimensions. Here the instantons are particle-like solitons and the theories are non-renormalizable. We present an explicit and calculable model in d = 2+1 dimensions where the single soliton in the CP^N sigma-model can be shown to be a multi-particle state whose partons are identified with the ultra-violet degrees of freedom which render the theory well-defined at high energies. We introduce a number of methods which reveal the partons inside the soliton, including deforming the sigma model and a dual version of the Bogomolnyi equations. We conjecture that partons inside Yang-Mills instantons hold the key to understanding the ultra-violet completion of five-dimensional gauge theories.

Supersymmetric probe branes satisfy the κ-symmetry condition which ensures that the action is minimized with respect to both variations of the embedding and of the world-volume gauge field. We observe that the κ-symmetry condition for a D7-brane in an imaginary self-dual (ISD) background can be generalized yielding minimization of the action with respect to variations of the gauge field only but not of the embedding. This provides a new way to construct non-BPS solutions for D7-branes once the embedding extremizes the geometrical volume of the brane. We then apply this method to the Klebanov-Strassler background and find a new D7−7 brane configuration that realizes the spontaneous breaking of flavor chiral symmetry as evidenced by the Goldstone boson identified in the spectrum. This result generalizes our previous construction for the Klebanov-Witten model. We compare our setup with the Sakai-Sugimoto model and discuss possible applications to QCD-like physics.

Applying the AdS/CFT correspondence, the expansion of the heavy-quark potential of = 4 supersymmetric Yang-Mills theory at large N_c is carried out to the sub-leading term in the large 't Hooft coupling at zero temperature. The strong coupling corresponds to the semi-classical expansion of the string-sigma model, the gravity dual of the Wilson loop operator, with the sub-leading term expressed in terms of functional determinants of fluctuations. The singularities of these determinants are examined and their contributions are evaluated numerically.

We analytically study two-color QCD with an even number of flavors at high baryon density. This theory is free from the fermion sign problem. Chiral symmetry is broken spontaneously by the diquark condensate. Based on the symmetry breaking pattern we construct the low-energy effective Lagrangian for the Nambu-Goldstone bosons. We identify a new epsilon-regime at high baryon density in which the quark mass dependence of the partition function can be determined exactly. We also derive Leutwyler-Smilga-type spectral sum rules for the complex eigenvalues of the Dirac operator in terms of the fermion gap. Our results can in principle be tested in lattice QCD simulations.

We consider corrections to the unification of down-quark and charged-lepton Yukawa couplings in supersymmetric GUTs, which links the large ν_τ−ν_μ mixing angle to b → s transitions. These corrections generically occur in simple grand-unified models with small Higgs representations and affect s → d and b → dtransitions via the mixing of the corresponding right-handed superpartners. On the basis of a specific SUSY-SO(10) model, we analyze the constraints from K− and B_d−_dmixing on the additional _R−_R rotation angle θ. We find that _K already sets a stringent bound on θ, θ^max ∼ (1°), indicating a very specific flavor structure of the correction operators. The impact of the large neutrino mixings on the unitarity triangle analysis is also briefly discussed, as well as their ability to account for the sizeable CP-violating phase observed recently in B_s → J/ψϕ decays.

Various aspects of time-dependent processes are studied within the large N approximation of O(N) vector models in three dimensions. These include the rolling of fields, the tunneling and decay of vacua. We present an exact solution for the quantum conformal case and find a solution for more general potentials when the total change of the value of the field is small. Characteristic times are found to be shorter when the time dependence of the field is taken into account in constructing the exact large N effective potentials. We show that the different approximations yield the same answers in the regions of the overlap of the validity. A numerical solution of this potential reveals a tunneling in which the bubble that separates the true vacuum from the false one is thick.