Table of contents

The Third Symposium on Prospects in the Physics of Discrete Symmetries (DISCRETE 2012) was held at Instituto Superior Técnico, Portugal, from 3–7 December 2012 and was organised by Centro de Física Teórica de Partículas (CFTP) of Instituto Superior Técnico, Universidade Técnica de Lisboa. This is the sequel to the Symposia that was successfully organised in Valéncia in 2008 and in Rome in 2010.

The topics covered included:

• T, C, P, CP symmetries

• CPT symmetry, decoherence, Lorentz symmetry breaking

• Discrete symmetries and models of flavour mixing

• Baryogenesis, leptogenesis

• Neutrino physics

• Electroweak symmetry breaking and physics beyond the Standard Model

• Accidental symmetries (B, L conservation)

• Experimental prospects at LHC

• Dark matter searches

• Super flavour factories, and other new experimental facilities

The Symposium was organised in plenary sessions with a total of 24 invited talks, and parallel sessions with a total of 70 talks, including both invited and selected contributions from the submitted abstracts. The speakers of the plenary sessions were: Ignatios Antoniadis, Abdelhak Djouadi, Rabindra Mohapatra, André Rubbia, Alexei Yu Smirnov, José Bernabéu, Marco Cirelli, Apostolos Pilaftsis, Antonio Di Domenico, Robertus Potting, João Varela, Frank Rathmann, Michele Gallinaro, Dumitru Ghilencea, Neville Harnew, John Walsh, Patrícia Conde Muíño, Juan Aguilar-Saavedra, Nick Mavromatos, Ulrich Nierste, Ferruccio Feruglio, Vasiliki Mitsou, Masanori Yamauchi, and Marcello Giorgi.

The Symposium was attended by about 140 participants. Among the social events, there was a social dinner in the historical Associação Comercial de Lisboa, which included a musical performance of 'Fado', the traditional music from Lisbon.

The next symposium of the series will be organised by King's College, London University, UK, from 1–5 December 2014.

Guest Editors

G C Branco, D Emmanuel-Costa, R González Felipe, F R Joaquim, L Lavoura, S Palomares-Ruiz, M N Rebelo, J C Romão, J P Silva and J I Silva-Marcos

Secretariat

• Dulce Conceição

• Sandra Oliveira

• Cláudia Romão

discrete2012@cftp.ist.utl.pt

http://indico.cern.ch/event/discrete2012

Sponsors

• CFTP – Centro de Física Teórica de Partículas

• LIP – Laboratório de Instrumentação e Física Experimental de Partículas

• IST – Instituto Superior Técnico

• FCT – Fundação para a Ciência e a Tecnologia

The PDF also contains the conference poster and a list of participants.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

I will discuss the status of the mass hierarchy problem and prospects for beyond the Standard Model physics in the light of the Higgs scalar discovery at the LHC and the experimental searches for new physics. In particular, I will discuss in this context low energy supersymmetry, living with the fine tuning and strings at the TeV scale.

The implications of the discovery of the Higgs boson at the LHC with a mass of approximately 125 GeV are discussed in the context of minimal supersymmetric extension of the Standard Model, the MSSM.

Understanding flavor is one of the fundamental puzzles of the standard model. The discovery of neutrino masses in the past decade, exhibiting mixing and mass patterns so very different from the quark sector has added an extra dimension to this problem. In this paper, I discuss a proposal that appears to provide a promising way to resolve this puzzle in a unified framework incorporating both quarks and leptons.

Status of the discrete symmetry approach to explanation of the lepton masses and mixing is summarized in view of recent experimental results, in particular, establishing relatively large 1-3 mixing. The lepton mixing can originate from breaking of discrete flavor symmetry G_f to different residual symmetries G_ℓ and G_v in the charged lepton and neutrino sectors. In this framework the symmetry group condition has been derived which allows to get relations between the lepton mixing elements immediately without explicit model building. The condition has been applied to different residual neutrino symmetries G_v. For generic (mass independent) G_v = Z₂ the condition leads to two relations between the mixing parameters and fixes one column of the mixing matrix. In the case of G_v = Z₂ × Z₂ the condition fixes the mixing matrix completely. The non-generic (mass spectrum dependent) G_v lead to relations which include mixing angles, neutrino masses and Majorana phases. The symmetries G_ℓ, G_v, G_f are identified which lead to the experimentally observed values of the mixing angles and allow to predict the CP phase.

A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique opportunity for a search of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and PHI, Factories. The two quantum effects of the first decay as a filtering measurement and the transfer of information to the still living partner allow performing a genuine TRV asymmetry with the exchange of "in" and "out" states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system.

I present a phenomenological, data-centered and data-driven assessment of the status of indirect searches for particle Dark Matter, with the main focus on some recent "anomalies" and of the main implications for DM model building. Tantalizing hints and stringent constraints seem to continuosly chase each other, as a number of well performing experiments keep delivering their data. This year may be the one in which we finally see the resolution of these dark puzzles, or it may not.

We briefly review the scenario of baryogenesis through leptogenesis. Leptogenesis is an appealing scenario that may relate the observed baryon asymmetry in the Universe to the low-energy neutrino data. Particular emphasis will be laid on recent developments on the field, such as the flavourdynamics of leptogenesis, resonant leptogenesis near the electroweak phase transition and thermal effects. It is illustrated how these recent developments enable the modelling of phenomenologically predictive scenarios that can directly be tested at the LHC and indirectly in low-energy experiments of lepton-number and lepton-flavour violation.

The status of present experiments and future projects with kaons is reviewed, focusing on prospects for discrete symmetries tests.

During the past two decades there has been a growing interest in the possibility that Lorentz and/or CPT might not be exact symmetries of Nature. In this short review, we present the current state of affairs, addressing both theoretical and experimental/observational issues. We pay particular attention to the role that has been played by the so-called Standard Model Extension.

The measurement of the properties of the recently discovered boson is central to the LHC physics program. In this contribution we review preliminary measurements of the properties of the new 125 GeV boson performed by the CMS experiment using the full proton-proton dataset collected in 2011–12 (~25 fb⁻¹). In the H → ZZ (4l) channel, a signal significance of 6.7σ is now observed. In the other high-resolution mode, H → γγ, updated results were obtained on the signal strength, μ = σ/σ_SM, which is now measured to be ~0.8 ± 0.3. The two high-resolution modes allowed independent determinations of the Higgs mass: 125.8±0.6 GeV, in H → ZZ (4l); and 125.4±0.8 GeV, in H → γγ. The four-lepton channel permitted tests of the spin-parity of the new boson. From these studies, the pure pseudoscalar hypothesis is excluded at 99.8% C.L. and, for the first time, simple spin 2 models are excluded with greater than 98.5% C.L. Significantly, strong evidence is seen in a fermionic decay mode of the Higgs for the first time, namely in the H → ττ channel, which is reported with a significance of nearly 3σ. The new measurements of the spin-parity (J^P) assignments for this particle, coupled with the measured strength of the interaction of this particle with other particles, strongly indicates that the new particle is a Higgs boson, responsible for the Electroweak Symmetry Breaking. While all of these measurements are consistent with values predicted for a SM Higgs boson, they still fall far short of the requisite precision to rule out all BSM scenarios. Additional data from Run 2 of the LHC and HL-LHC will be needed to firmly establish this conclusion.

The Standard Model (SM) of Particle Physics is not capable of accounting for the apparent matter-antimatter asymmetry of our universe. Physics beyond the SM is required and is searched for by (i) employing highest energies (e.g., at LHC), and (ii) striving for ultimate precision and sensitivity (e.g., in the search for electric dipole moments (EDMs)). Permanent EDMs of particles violate both time reversal (T) and parity (P) invariance, and are via the CPT-theorem also CP-violating. Finding an EDM would be a strong indication for physics beyond the SM, and reducing upper limits further provides crucial tests for any corresponding theoretical model, e.g., SUSY. Direct searches for proton and deuteron EDMs bear the potential to reach sensitivities beyond 10⁻²⁹ e·cm. For an all-electric proton storage ring, this goal is pursued by the US-based srEDM collaboration [1], while the newly founded Jülich-based JEDI collaboration [2] is pursuing an approach using a combined electric-magnetic lattice, which shall provide access to the EDMs of protons, deuterons, and ³He ions in the same machine. In addition, JEDI has recently proposed making a direct measurement of the proton and/or deuteron EDM at COSY using resonant techniques involving Wien filters.

The top quark, the heaviest known elementary particle discovered at the Fermilab Tevatron almost twenty years ago, has taken a central role in the study of fundamental interactions. The top quark behaves differently from all other quarks due to its large mass and its correspondingly short lifetime. Its large mass suggests that it may play a special role in nature. The top quark decays before it hadronizes, passing its spin information on to its decay products. Therefore, it is possible to measure observables that depend on the top quark spin, providing a unique environment for tests of the standard model and for new physics searches. With approximately 10 fb⁻¹ of luminosity delivered to each experiment at the Tevatron, and about 20 fb⁻¹ collected by the ATLAS and CMS experiments at the Large Hadron Collider in the first three years of operation, top quark physics is at a turning point from first studies to precision measurements with sensitivity to new physics processes. This report summarizes the latest experimental measurements and studies of top quark properties and rare decays.

One of the primary goals of the B factory experiments was to measure and study CP violation in B meson decays, a goal which has been met very successfully. This paper reports on recent measurements of CP violation at the Babar and Belle experiments. Particular focus is placed on the measurements of the three angles of the Unitarity Triangle, β, α and γ.

The ATLAS experiment is situated at the Large Hadron Collider at CERN (Geneva). It was designed to cover a wide range of physics topics, such as precision measurements of Standard Model physics, the determination of the Electroweak Symmetry Breaking mechanism through the search for the Higgs boson, and searches for new physics beyond the Standard Model, like super-symmetric particles. ATLAS started operation at the LHC at the end of 2009, collecting poton-proton collisions at 7 and 8 TeV centre of mass energies. In this paper a summary of some of the most interesting recent physics ATLAS results will be presented.

We present the current status of the Tevatron charge asymmetry and its sister asymmetry at the LHC. The relation between both is elucidated, using as framework the collider-independent asymmetries they originate from. Other related observables, such as the t differential distribution and top polarisation, are also discussed.

In this talk, I review some plausible scenarios entailing violation of CPT symmetry in the early Universe, due to space-time backgrounds which do not respect some of the assumptions for the validity of the CPT theorem (here considered will be Lorentz invariance and/or Unitarity). The key point in all these models is that the background induces different populations of fermions as compared to antifermions, and hence CPT Violation (CPTV), already in thermal equilibrium. Such populations may freeze out at various conditions depending on the details of the underlying microscopic model, thereby leading to leptogenesis and baryogenesis. Among the considered scenarios is a stringy one, in which the CPTV is associated with a cosmological background with torsion provided by the Kalb-Ramond antisymmetric tensor field (axion) of the string gravitational multiplet. We also discuss briefly (Lorentz Violating) CPTV models that go beyond the local effective lagrangian framework, such as a stochastic Finsler metric and D-particle foam. In the latter, the CPTV is induced by the interactions of stringy matter with populations of stochastically fluctuating point-like space-time defects (D-particles) that can be encountered in string/brane Cosmologies. The preferential rôle of neutrinos is singled out in this latter scenario as a consequence of gauge symmetry (charge) conservation.

In this talk I review the status of B− mixing in the Standard Model and the room for new physics in B_s−_s and B_d−_d mixing in the light of recent LHCb data.

I shortly review the impact of the most recent neutrino oscillation data on our attempts to construct a realistic model for neutrino masses and mixing angles. Models based on anarchy and its variants remain an open possibility, reinforced by the latest experimental findings. Many models based on discrete symmetries no longer work in their simplest realizations. I illustrate several proposals that can rescue discrete symmetries. In particular I discuss the possibility of combining discrete flavour symmetries and CP, and I describe a recently proposed symmetry breaking pattern that allows to predict all mixing parameters, angles and phases, in terms of a single real unknown. I analyze several explicit examples of this construction, providing new realistic mixing patterns.

An overview of supersymmetry searches is presented, covering collider experiments, direct and indirect searches for supersymmetric dark matter. Recent LHC experimental results are reviewed, and the constraints from B-meson decays are reported. Implications for supersymmetry of the latest direct and indirect searches are thoroughly discussed. The focus is on the complementarity of the various probes – particle and astrophysical – for constraining Supersymmetry.

In pp collisions at the LHC the LHCb experiment has collected the world's largest sample of charmed hadrons. Using data of an integrated luminosity of 1.0 fb⁻¹ recorded in 2011 a measurement of direct and indirect CP violation in the charm sector and of D⁰ mixing parameters was performed. Results from several decay modes are presented with complementary time-dependent and time-integrated analyses.

Three methods of measuring the violating quantities a^s_fs and a^d_fs are discussed. The LHCb experiment is used to measure semi-leptonic B_d and B_s decays from pp collisions created by the Large Hadron Collider. The flavour specific decays of B_s → D_s(ϕπ)μv are selected and the final state charge asymmetry is measured, which to first order is proportional to a^s_fs. This is done by fitting the KKπ invariant mass distributions to determine the yield of both D⁺_sμ⁻ and D⁻_sμ⁺ events. The charge-dependant efficiency for selecting this decay is measured using data-driven techniques. Using this information, the yields are corrected and the final state charge asymmetry is obtained, resulting in a^s_fs = (−0.24±0.54±0.33)%. Finally two proposed LHCb measurements are described: a time-dependent difference and sum measurement a^s_fs ± a^d_fs and a time-dependent measurement of a^d_fs

Determination of the CP-violating phase ϕ_s in B⁰_s → J/ψ K⁺K⁻ decays is one of the key goals of the LHCb experiment. Its value is predicted to be very small in the Standard Model but can be significantly enhanced in many other models. We present the most precise measurement of ϕ_s to date and the first observation of a non-zero ΔΓ_s based upon 1 fb⁻¹ of data collected at LHCb during 2011. Also the measurement of ϕ_s with the decay mode B⁰_s → J/ψπ⁺π⁻ and a combination of the J/ψK⁺K⁻ and J/ψπ⁺π⁻ results are reported. Additionally we present first results from the measurement of the decay , which is potentially interesting for controlling currently neglected higher order corrections in B⁰_s → J/ψK⁺K⁻.

Test of Time Reversal Invariance in pd scattering is planned at the COoler-SYnchrotron COSY-Jülich using the PAX internal target station. Feasibility test, performed in September 2012, have shown possibility to perform such an experiment using COSY and PAX. In parallel to the PAX upgrade a new high precision beam current measurement system will be constructed by the end of 2014. After these modifications, it will be possible to improve the current upper limit on a strength of T-odd P-even NN potential by an order of magnitude.

Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavour states (B⁰ or ⁰), and J/ψK⁰_L or cK⁰_s final states (referred to as B₊ or B₋), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, ⁰ → B₋ and B₋ → ⁰, as a function of the time difference between the two B decays. Using 468 million B pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, T-violating parameters in the time evolution of neutral B mesons have been measured, yielding ΔS⁺_T = −1.37 ± 0.14 (stat.) ± 0.06 (syst.) and ΔS⁻_T = 1.17 ± 0.18 (stat.) ± 0.11 (syst.) [1]. These non-zero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.

A measurement of several properties of the B_s meson, including the CP-violating weak phase ϕ_s and the mixing-induced width difference ΔΓ_s, is performed using the decay B_s → J/ψ(μ⁺μ⁻)ϕ(K⁺K⁻), from a dataset of 4.9 fb⁻¹ of integrated luminosity collected in 2011 by the ATLAS detector at the LHC. The measured parameters are consistent with the world average values and theoretical expectations; in particular ϕ_s is within 1 σ of the expected value in the Standard Model.

The LHCb experiment is a general purpose forward spectrometer operating at the Large Hadron Collider, optimized for the study of B and D hadrons. LHCb collected ~1 fb⁻¹ of integrated luminosity during 2011 data taking, which provides an unprecedentedly large sample of B hadron decays to final states involving charmed hadrons. These decays offer many complementary ways to measure the angle γ of the CKM triangle. We present a selection of new world-leading measurements of CP-violating observables in these decays, using both time-independent and, for the first time, time-dependent analyses. A first LHCb combination of the time-independent measurements to provide a value of γ is also presented.

In the Standard Model CP violation in charm decays is expected to be very small, at the level of 0.1% or below, while CP violation in τ decays is predicted to be negligible. A significant excess of CP violation with respect to the Standard Model predictions would be a signature of new physics. We report on recent searches for CP violation in charm meson decays and in τ lepton decays at BABAR, using a data sample corresponding to an integrated luminosity of about 470 fb⁻¹. In particular, we report on searches for CPV in the decay modes with a K⁰_S in the final state, such as D⁺ → K⁰_SK⁺, D⁺_s → K⁰_SK⁺, D⁺_s → K⁾_Sπ⁺ and τ⁺ → π⁺K⁰_Sτ, and in the 3-body D⁺ → K⁺K⁻π⁺ decay. A lifetime ratio analysis of D⁰ → K⁺K⁻, π⁺π⁻ with respect to D⁰ → K⁻π⁺ decays, which is sensitive to D⁰-⁰ mixing and CP violation, is also presented here.

We present a new search for the K_S → 3π⁰ decay performed with the KLOE detector operating at the DAΦNE ϕ-factory. The K_S mesons were tagged via registration of K_L mesons which crossed the drift chamber without decaying and interacted with the KLOE electromagnetic calorimeter. The K_S → 3π⁰ decay was then searched requiring six prompt photons. To suppress background, originating from fake K_S tags and K_S → 2π⁰ decays with additional two spurious clusters, we have performed a discriminant analysis based on kinematical fit, testing of the signal and background hypotheses and exploiting of the differences in kinematics of the K_S decays into 2π⁰ and 3π⁰. In a sample of about 1.7·10⁹ϕ → K_SK_L events we have found no candidates in data and simulated background samples. Normalizing to the number of K_S → 2π⁰ events in the same sample, we have set the upper limit on the K_S → 3π⁰ branching ratio BR(K_S → 3π⁰) < 2.6 · 10⁻⁸ at 90% C.L., five times lower than the previous limit. This upper limit can be translated into a limit on the modulus of the η₀₀₀ parameter amounting to |η₀₀₀| < 0.0088 at 90% C.L., improving by a factor two the latest direct measurement.

In this talk I will review two recent results of CP Violation in B decay analyses obtained by the BaBar experiment. Using the full data set and the partial reconstruction of the D* meson BaBar has measured the CPV parameters in the B⁰ → D^*+D^*− decay and in the semileptonic decay ⁰ → D^*+ℓ⁻_ℓ.

The search for new physics in top quark decays at the LHC is reviewed in this paper. Results from ATLAS [1] and CMS [2] experiments on top quark decays within the Standard Model are presented together with the measurements of the W boson polarizations and the study of the structure of the Wtb vertex. As a natural step forward, the experimental status on measurements sensitive to top quark couplings to gauge bosons (γ, Z, W and H) is reviewed as well as possible top quark decays Beyond the Standard Model (MSSM and FCNC).

In this work we present a new Monte Carlo generator for Direct top and Single top production via flavour-changing neutral currents (FCNC). This new tool calculates the cross section and generates events with Next-to-Leading order precision for the Direct top process and Leading-Order precision for all other FCNC single top processes. A set of independent dimension six FCNC operators has been implemented – including four-fermion operators – where at least one top-quark is present in the interaction.

In this paper we study the effect of new physics contributions to the top quark pair production (t) in a possible future linear collider, such as the International Linear Collider (ILC). The use of a dimension-six gauge invariant effective operator approach allows to compare the prospected results at the ILC with the current ones obtained at the Large Hadron Collider (LHC), both in neutral and charged current processes. We also prove that the use of specific observables, together with a combination of measurements in different polarized beam scenarios and with different center-of-mass energies, allows to disentangle different effective operator contributions and significantly improve the limits on the anomalous couplings with respect to the LHC.

A review of the measurements of the t production cross section (inclusive and differential) performed by the CMS experiment at the LHC is given. The results are used to constrain the magnitude of most of the relevant systematics affecting precision measurements in the top quark sector. In addition from the determination of the top quark pair production cross section it is possible to determine the strong coupling constant as α_S(m_Z) = 0.1178^+0.0046_−0.0040 in agreement with the current world average. After the combination of several channels and techniques explored to measure the top quark mass in data, a precise determination of this quantity is made at CMS: m_t = 173.4±0.4_stat ± 0.9_syst GeV. The measurement of the difference Δm_t = m_t − m is also presented.

The two-loop renormalization group equations for the parameters of softly broken supersymmetric gauge theories given in the literature are generalized to the case when the gauge group contains more than a single abelian factor. This contribution to the proceedings of the DISCRETE 2012 symposium is based on reference [1].

We study the potential of an e^±e⁻ Linear Collider for charged lepton flavour violation studies in a supersymmetric framework where neutrino masses and mixings are explained by a type-I seesaw. Focusing on e-μ flavour transitions, we evaluate the background from standard model and supersymmetric charged currents to the eμ + signal. We study the energy dependence of both signal and background, and the effect of beam polarisation in increasing the signal over background significance. Finally, we consider the μ⁻μ⁻ + final state in e⁻e⁻ collisions that, despite being signal suppressed by requiring two e-μ flavour transitions, is found to be a clear signature of charged lepton flavour violation due to a very reduced standard model background. This contribution summarises part of the work done in [1].

We construct supersymmetric SO(10) models with different intermediate scales, consistent with gauge coupling unification. We found the complete list of sets of fields that can be added in each regime that allows to preserve unification and a "sliding scale mechanism". Using mSugra boundary conditions we calculate some particular combinations of soft SUSY breaking terms, called "invariants", that depend on the squark, slepton and gaugino mass spectra. We classify these invariants into a small number of sets, and show that their measurements contain indirect information about the class of models and the scale of beyond-MSSM physics.

In minimal supersymmetric seesaw models, the contribution to lepton flavour violation from Z-penguins is usually negligible. In this study, we consider the supersymmetric inverse seesaw and show that, in this case, the Z-penguin contribution dominates in several lepton flavour violating observables due to the low scale of the inverse seesaw mechanism. Among the observables considered, we find that the most constraining one is the μ-e conversion rate which is already restricting the otherwise allowed parameter space of the model. Moreover, in this framework, the Z-penguins exhibit a non-decoupling behaviour, which has previously been noticed in lepton flavour violating Higgs decays.

We review and clarify some cases of geometrical CP violation, the framework of spontaneous CP violation through complex phases with values that are independent of parameters of the potential. We present a flavour model based on Δ(27) featuring spontaneous CP violation, that can reproduce all quark masses and mixing data. The scalar sector of the model has exotic properties that can be tested at the LHC.

In beyond Standard Model physics scenarios one often has to extend the Higgs sector and introduce additional (discrete) symmetries. In such models it is possible that the Weinberg operator is forbidden and the leading contribution to neutrino mass is generated by operators with mass dimension d > 5. These higher-dimensional operators are stronger suppressed and therefore the new physics scale can be as low as the TeV scale. With this approach it is possible to test neutrino mass models at colliders, such as the LHC. We will demonstrate how these operators can be systematically studied and present an exemplary implementation of such a model and its phenomenological consequences. We also show how it can be embedded into an SU(5) GUT framework. Finally we present a specific realization of this model where we can have tri-bimaximal mixing with large deviations due to a softly broken symmetry.

We consider an enhancement in the violation of lepton flavour universality in light meson decays arising from modified Wℓν couplings in the standard model minimally extended by sterile neutrinos. Due to the presence of additional mixings between the active neutrinos and the new sterile states, the deviation from unitarity of the leptonic mixing matrix intervening in charged currents might lead to a tree-level enhancement of R_P = Γ(P → ev)/Γ(P → μν), with P = K, π. These enhancements are illustrated in the case of the inverse seesaw, showing that one can saturate the current experimental bounds on Δr_K (and Δr_π), while in agreement with the different experimental and observational constraints.

We study the neutrino mass spectrum in the context of the adjoint SU(5) model constrained by a Z₄ flavour symmetry that imposes the nearest-neighbour interaction form on both up- and down-quark mass matrices. We show that at least three adjoint fermionic fields are required in order to reproduce the light neutrino mass spectrum.

The measurement of the last neutrino mixing angle θ₁₃ giving a a non zero value has established a new challenge for the theoretical understanding of the lepton mixing. The use of discrete symmetries to successfully explain that mixing is still possible. As an example, we have modified the so called Babu-Ma-Valle model in such a way that we account for the current neutrino mixing values at 3σ. In particular, we have obtained not only compatibility with a θ₁₃ ≠ 0, but also a non maximal θ₂₃.

A procedure for using the eigenvectors of the elements of the representations of a discrete group in model building is introduced and is used to construct a model that produces a large reactor mixing angle, , in agreement with recent neutrino oscillation observations. The model fully constrains the neutrino mass ratios and predicts normal hierarchy with the light neutrino mass, m₁ ≈ 25 meV. Motivated by the model, a new mixing ansatz is postulated which predicts all the mixing angles within 1σ errors.

The present article gives an overview of the status of Higgs boson studies in the ATLAS experiment at the LHC, at the time of the DISCRETE 2012 Symposium. Accounts of the latest Higgs boson searches in the H → WW^(*) → ℓνℓν, H → b and H → τ⁺τ⁻ channels are given, as well as a summary of the investigation into the couplings of the new particle, and an indication of the sensitivity of future Higgs studies at the LHC.

Rare leptonic decays of the B⁰_(s), D and K mesons are sensitive probes of physics beyond the Standard Model. In particular, the search for the decays B⁰_(s) → μ⁺μ⁻ provides information on the presence of new (pseudo-)scalar particles. LHCb is well suited for these analyses due to its large acceptance for B-decays and trigger efficiency, as well as its excellent invariant mass resolution and electron and muon identification capabilities. Results on these searches using data collected by LHCb in 2011 and 2012 are presented.

The LHCb experiment is designed to perform high-precision measurements of CP violation and search for New Physics using the enormous flux of beauty and charmed hadrons produced at the Large Hadron Collider (LHC). The operation and the results obtained from the data collected 2011 and 2012 demonstrate that the detector is robust and functioning very well. However, the limit of (1)fb⁻¹ of data per year cannot be overcome without improving the detector. We therefore plan for an upgraded spectrometer by 2018 with a 40MHz readout and a much more flexible software-based triggering system that will increase the data rate as well as the efficiency specially in the hadronic channels. Here we present the LHCb detector upgrade plans.

During 2011 the ATLAS experiment at CERN collected around 5 fb⁻¹ of proton-proton collision data from the LHC at the center-of-mass energy of = 7 TeV. At such high energy frontier it is possible to explore possible new physics scenarios. Amongst the models of physics beyond the Standard Model (SM) some predict the existence of exotic heavy quarks, which would help to explain matter-antimatter asymmetry and to solve the hierarchy problem. Several analyses at ATLAS were performed to search for a chiral 4th generation of quarks with charges +2/3 and −1/3 (t' and b' respectively) and for vector-like quarks with charges of +2/3, −1/3, +5/3, −4/3, coming in singlets or doublets depending on the model. The recent discovery of a Higgs-like, SM-like boson with mass of ~ 125 GeV makes the vector-like quark scenario the most interesting one. The status of these searches and the limits set at 95% Confidence Level (CL) are presented.

In the minimal super-symmetric extension of the Standard Model (MSSM), the Higgs sector contains two Higgs boson doublets, including, after electroweak symmetry breaking, the CP-odd neutral scalar A⁰, the two charged scalars H^±, and the two CP-even neutral scalars h and H⁰. The neutral Higgs boson is searched in the μ⁺μ⁻, τ⁺τ⁻, and recently also in the b, channels, whereas the charged Higgs state is searched in top quark decays with at least one τ in the final state. This report reviews the current status of searches for MSSM Higgs bosons with the data collected by the CMS experiment at LHC in the 2011 and 2012 operations.

Results are presented on the search for the Standard Model (SM) Higgs bosons decaying into two photons, ZZ and two taus. Multivariate techniques are used to enhance the sensitivity. The full data sample of 5.1 fb⁻¹ of pp collisions collected in 2011 at a CM energy of 7 TeV with the CMS experiment has been analyzed, as well as a significant fraction of the 2012 luminosity delivered at the new CM energy of 8 TeV.

Properties of the Z₂-symmetric Two Higgs Doublet Models (2HDM) are discussed and confronted with new LHC data for a 125 GeV Higgs particle. The particle discovered at LHC in 2012 has properties expected for it in the Standard Model (SM), with a possible enhancement in the γγ channel. SM-like Higgs scenarios can be realized in the Two Higgs Doublet Models with Z₂ (D) symmetry within the normal Mixed Model (with scalar sector as in MSSM) and the Inert Doublet Model (IDM), where a good Dark Matter (DM) candidate is present. Here we discuss both of the models.

The two-Higgs doublet model (2HDM) can have two electroweak breaking, CP-conserving, minima. The possibility arises that the minimum which corresponds to the known elementary particle spectrum is metastable, a possibility we call the "panic vacuum". We present analytical bounds on the parameters of the softly broken Peccei-Quinn 2HDM which are necessary and sufficient conditions to avoid this possibility. We also show that, for this particular model, the current LHC data already tell us that we are necessarily in the global minimum of the theory, regardless of any cosmological considerations about the lifetime of the false vacua.

We review and update the current phenomenological constraints on minimal type I seesaw extensions of the Standard Model in which New Physics content can be probed at the electroweak scale. In this class of models, the flavour structure of the neutrino Yukawa couplings is determined by the requirement of reproducing neutrino oscillation data. The strongest constraints on the seesaw parameter space are imposed by the very recent upper limit on μ → eγ decay rate. Searches of non-standard Higgs boson decays into a light and a heavy neutrino may also provide and independent test of these seesaw scenarios.

We present a brief overview of a unified treatment of masses and mixings of quarks and leptons, as a realization of an S₃-flavour permutational symmetry in an extension of the Standard Model. In order to leave S₃ as an exact flavour symmetry two extra Higgs fields, SU(2)_L doublets, are added. In this model, the mass matrices of the fermions are reparametrized in terms of their eigenvalues allowing us to derive exact, explicit analytical expressions for the mixing matrices, V^th_CKM and U^th_PMNS, as functions of the quark and lepton masses, respectively. In both the quark and lepton sectors a χ² fit of the theoretical expressions to the experimentally determined values of the mixing angles yields results in excellent agreement with the most recent experimental data on quarks and leptons.

We study the fit of the Higgs boson rates, based on all the collider data, in the effective framework for any Extra-Fermion(s) [EF]. The best-fit results are presented in a generic formalism allowing to apply those for the test of any EF scenario. The variations of the fit with each one of five fundamental parameters are described.

We carry out a detailed analysis of a minimal S₃-invariant extension of the Standard Model, with an extended S₃-Higgs sector. Within this extended S(3)-Standard Model, we study the trilinear Higgs couplings and its dependence on the details of the model, even when the lightest Higgs boson mass is taken to be a fixed parameter. We study quantitatively the trilinear Higgs couplings, and compare these couplings to the corresponding Standard Model trilinear Higgs coupling in some regions of the parameter space. A precise measurement of the trilinear Higgs self coupling will also make it possible to test this extended S(3)-Standard Model with the Standard Model trilinear Higgs coupling. We present analytical expressions for the trilinear Higgs couplings.

Tuning effect in particle masses manifests itself in integer relations between lepton masses and parameters of the pion (its mass, the mass splitting and f_π). It involves parameters of constituent quark model and basic values of the Standard Model: masses of vector and scalar bosons, QED parameters and the top quark mass. The role of nuclear data is discussed.

The main production mode for a light charged Higgs boson at the LHC is pp → t, with one the top-quarks decaying to a charged Higgs and a b-quark. However, single top production also gives rise to final states with charged Higgs bosons. In this work we analyse how the two processes compare at the LHC@14TeV. We will be working in the framework of the two-Higgs double model, considering both a CP-conserving and a CP-violating version of the model. We conclude that the single top mode could help to constrain the parameter space in several versions of the model. We also discuss the role of other complementary production processes in future searches at the LHC.

A sizable excess with respect to the SM expectation has been reported recently by the BaBar collaboration in the decay rates B → D^(*)τν, normalized by the corresponding light lepton modes. A violation of lepton flavor universality as suggested by this excess could be due to a charged Higgs mediating these processes at tree level. In this talk we analyze the implications of the observed excess within the framework of two-Higgs-doublet models, considering also the bounds from other semileptonic and leptonic decays of B and D_(s) mesons. Prospects for B → D^(*)τν decays at future Super-Flavor Factories are also discussed.

We revise the prospects for the observation of charged lepton flavour violation (LFV), in the light of the recent results from the LHC, MEG and neutrino experiments. We work in the context of the Minimal Supersymmetric Standard Model (MSSM) extended with massive neutrinos arising from a see-saw mechanism. The connection between the observed neutrino oscillations with flavour oscillations in the charged sector is established using a model for the Yukawa couplings arising from a SU(5) grand unified theory (GUT) with Abelian flavour symmetries. We discuss in this scenario the possible observation on the radiative decays μ → eγ and τ → μγ and LFV processes that could be detectable at a linear collider (LC) with a centre-of-mass energy in the TeV range.

From the naturalness point of view, the first LHC results seem to disfavour any constrained MSSM realization with universal conditions at the SUSY-breaking scale. A more motivated scenario is given by split-family SUSY, in which the first two generations of squarks are heavy, compatible with a U(2)³ flavour symmetry. Here, after reviewing the flavour structures obtained in this framework, we consider the flavour symmetry to be broken at a very high scale, and study the consequences at low energies through its RGE evolution. Initial conditions compatible with a split scenario are found, and the preservation of correlations from minimal U(2)³ breaking are checked.

We present a detailed analysis of recent flavour data in the framework of a simple extension of the Standard Model, where a Q = 2/3 vector-like isosinglet quark is added to the spectrum. Constraints from all the relevant quark flavour sectors are used. Important deviations from Standard Model expectations in different observables such as the semileptonic asymmetry in B_d decays, A^d_SL, the time-dependent CP asymmetry in B_s → J/ΨΦ, and rare decays such as K⁺ → π⁺ν can be obtained.

Searches for heavy Majorana neutrinos in B⁻ decays with final states containing hadrons plus a μ⁻μ⁻ pair are performed using 0.41 fb⁻¹ of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. No signals are found and upper limits are set on Majorana neutrino production and B⁻ decay branching fractions as a function of the Majorana neutrino mass.

A search is also made for the lepton flavour violating decay τ → μ⁺μ⁻μ⁻ using 1.0 fb⁻¹ of data collected by LHCb in 2011. The observed number of events is consistent with the background expectation, and an upper limit on the branching ratio is set. Using a similar procedure, the lepton flavour violating and baryon number violating decays τ⁻ → μ⁺μ⁻ and τ⁻ → pμ⁻μ⁻ are searched for, and upper limits provided at 95% confidence level.

We propose applications of Radioactive Ion Beam facilities to investigate physics beyond the Standard Model. In particular, we focus upon the search for sterile neutrinos by means of a low energy beta-beam with a Lorentz boost factor of 1. In the considered setup, collected ⁸Li radioactive ions are sent inside a 4π detector filled with a liquid scintillator, with inverse-beta decay as neutrino detection channel. We provide exclusion curves for the sterile neutrino mixing parameters, based upon the 3+1 formalism, depending upon the achievable ion intensity. The proposed experiment represents a possible alternative to clarify the current anomalies observed in neutrino experiments.

We report an early result from ICARUS (CNGS2), the large mass LAr-TPC, a Gargamelle class imaging detector of novel design. A search of a v_μ → ν_e signal due to a LSND anomaly at the Gran Sasso Laboratory, located at a distance of L = 730 km from CERN is hereby presented. Such an anomaly, in which an electron is produced by neutrinos in the energy interval 0 ≤ E_v ≤ 30 GeV, will be characterized by a fast energy oscillation averaging closely to sin²(1.27Δm²_newL/E_v) ≃ 1/2 and therefore approximately with probability . The presence of such a signal will be compared with the small but significant backgrounds due to other and more conventional neutrino origins. Within the range of our observations, our result is compatible with the absence of a LSND anomaly. At 90% and 99% confidence levels the limits on the oscillation probabilities are and respectively. The present result strongly limits the window of opened options for the LSND anomaly, reducing the remaining effect to a narrow region centered around (Δm², sin²(2θ)) = (0.5 eV²,0.05) where there is an over-all agreement (at 90 % CL) between the present ICARUS limit, the published limits of KARMEN and the published positive signals of LSND and MiniBooNE collaborations.

SNO+ is a multi-purpose Neutrino Physics experiment, succeeding to the Sudbury Neutrino Observatory by replacing heavy water with liquid scintillator. Its scientific goals are the search for neutrinoless double-beta decay, the study of solar neutrinos and antineutrinos from reactors and the Earth's natural radioactivity, as well as supernovae neutrinos. The experimental advantages of SNO+ are the possibility of loading large quantities of double-beta decaying isotope in the liquid scintillator volume, and the very low backgrounds allowed by the deep underground location and radiopurity of the employed materials. The installation of the detector at SNOLAB is being completed, and commissioning has already started, with a dry run. Filling with water and later, with scintillator, will start next year. This talk will summarize the Physics goals of SNO+, as well as the main detector developments.

One of the fundamental open questions in elementary particle physics is the value of the neutrino mass and its nature of Dirac or Majorana particle. Neutrinoless double beta decay (DBD0_ν) is a key tool for investigating these neutrino properties and for finding answers to the open questions concerning mass hierarchy and absolute scale. Experimental techniques based on the calorimetric approach with cryogenic particle detectors are proved to be suitable for the search of this rare decay, thanks to high energy resolution and large mass of the detectors. The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for DBD0_ν in ¹³⁰Te. The CUORE setup consists in an array of 988 tellurium dioxide crystals, operated as bolometers, with a total mass of about 230 kg of ¹³⁰Te. The experiment is under construction at the Gran Sasso National Laboratory in Italy. As a first step towards CUORE, a tower prototype (CUORE-0) has been assembled and is running. In this talk a detailed description of the CUORE-0 tower, its performances and the expected sensitivity will be given. The status of the CUORE experiment, its critical points and its expected sensitivity on the base of what we will learn with CUORE-0 will then be discussed.

We present a U(1) extension of the standard model that accounts after breaking for the small neutrino masses and the observed dark matter abundance. From the presence of the dark matter candidate, an original scenario of leptogenesis emerges, viable in a restricted region of the parameter-space. Relying on a rich scalar sector, this model can deviate from standard model Higgs phenomenology.

The existence of a light dark force mediator has been tested with the KLOE detector at DAΦNE. This particle, the so called dark photon U, has been searched for in three different processes and four different final states: a) Φ → ηU, with U → e⁺e⁻, η → π⁺π⁻π⁰ and η → π⁰π⁰π⁰; b) e⁺e⁻ → U_γ with U → μ⁺μ⁻; c) e⁺e⁻ → Uh' (dark Higgsstrahlung), U → μ⁺μ⁻, where h' is a Higgs-like particle responsible for the breaking of the hidden symmetry.

We did not find any evidence of the processes above and set upper limits on the parameters of the model, for different M_U (and M_h') mass ranges, depending on the considered final state.

The neutral kaon system offers a unique possibility to perform fundamental tests of fundamental symmetry such CP and CPT invariance. In this contribution the KLOE search for CPT symmetry and Lorentz Invariance breaking in the Standard Model Extension framework is reported. Preliminary results are:

One of the fundamental rules of nature and a pillar in the foundation of quantum theory and thus of modern physics is represented by the Pauli Exclusion Principle. We know that this principle is extremely well fulfilled due to many observations. Numerous experiments were performed to search for tiny violation of this rule in various systems. The experiment VIP at the Gran Sasso underground laboratory is searching for possible small violations of the Pauli Exclusion Principle for electrons leading to forbidden X-ray transitions in copper atoms. VIP is aiming at a test of the Pauli Exclusion Principle for electrons with high accuracy, down to the level of 10⁻²⁹ – 10⁻³⁰, thus improving the previous limit by 3–4 orders of magnitude. The experimental method, results obtained so far and new developments within VIP2 (follow-up experiment at Gran Sasso, in preparation) to further increase the precision by 2 orders of magnitude will be presented.

We present a new perturbative formulation of non-equilibrium thermal field theory, based upon non-homogeneous free propagators and time-dependent vertices. The resulting time-dependent diagrammatic perturbation series are free of pinch singularities without the need for quasi-particle approximation or effective resummation of finite widths. After arriving at a physically meaningful definition of particle number densities, we derive master time evolution equations for statistical distribution functions, which are valid to all orders in perturbation theory and all orders in a gradient expansion. For a scalar model, we make a loopwise truncation of these evolution equations, whilst still capturing fast transient behaviour, which is found to be dominated by energy-violating processes, leading to non-Markovian evolution of memory effects.