Table of contents

The third biannual conference on 'Discovery Physics at the LHC' was held on December 1-6 2014 at the Kruger Gate Hotel in South Africa. Over 100 participants attended from Austria, Australia, Belgium, Brazil, Canada, China, the Czech Republic, France, Germany, Italy, the Netherlands, Norway, Poland, South Africa, Switzerland, the UK and the USA. The latest results from the Large Hadron Collider as well the latest theoretical insights were presented. With the majestic Kruger National Park in the background this led to a very stimulating conference with many exchanges taking place. The proceedings reflect the high level of the conference. The financial contributions from the SA-CERN programme, the UCT-CERN Research Centre, the University of Johannesburg, the University of the Witwatersrand and iThemba L.A.B.S. are gratefully acknowledged.

Local Organizing Committee: Z. Buthelezi J. Cleymans (chair) S. H. Connell A. S. Cornell T. Dietel S. Förtsch N. Haasbroek A. Hamilton W. A. Horowitz B. Mellado Z. Z. Vilakazi S. Yacoob

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.

The evolution equations of the gauge and Yukawa couplings are derived for the two-loop renormalisation group equations in a five-dimensional SM compactified on a S¹/Z₂ to yield standard four space-time dimensions. Different possibilities can be discussed, however, we shall consider the limiting case in which all matter fields are localised on the brane. We will compare our two-loop results to the results found at one-loop level, and investigate the evolution of sin²θ_W in this scenario also.

We discuss the present status of the tomography of a quark gluon plasma (QGP) with help of heavy quarks. We address the question whether collisional or radiative energy loss dominates, how different expansion scenarios of the medium influence the observables and which state of the expansion is impressed in the R_AA and v₂ observables.

The current LHCb trigger system consists of a hardware level, which reduces the LHC inelastic collision rate of 30 MHz to 1MHz, at which the entire detector is read out. In a second level, implemented in a CPU farm, the event rate is reduced to about 5 kHz. The major bottleneck in LHCb's trigger efficiencies for hadronic heavy flavour decays is the hardware trigger. The LHCb experiment plans a major upgrade of the detector and DAQ system in the LHC shutdown of 2018. In this upgrade, a purely software based trigger system is being developed, which will have to process the full 30 MHz of inelastic collisions delivered by the LHC. Both the current trigger system and its planned upgrade are discussed in these proceedings.

CMS has searched for supersymmetry using the full dataset recorded until the end of 2012, at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20 fb⁻¹. The observations are consistent with the expectations from the standard model. CMS maintains a broad spectrum of search strategies that target a wide range of supersymmetric scenarios. A selection of results from very inclusive and almost model-independent searches to very specific and specialized analyses will be discussed in this article.

The dynamics of partons and hadrons in ultra-relativistic nucleus-nucleus collisions is analyzed within the Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model for the partonic phase (DQPM) including a dynamical hadronization scheme while reproducing lattice QCD results in thermodynamic equilibrium for the equation-of-state as well as transport coefficients like shear and bulk viscosities or the electric conductivity of the hot QCD medium. The PHSD model reproduces a large variety of observables from SPS to LHC energies, e.g. the quark-number scaling of elliptic flow, transverse mass and rapidity spectra of charged hadrons, dilepton spectra, open and hidden charm production, collective flow coefficients etc., which are associated with the observation of a strongly interacting QGP (sQGP). The 'highlights' of the latest results from LHC energies are presented with a focus on observable effects from the non-equilibrium initial dynamics.

The nature of the 125 GeV Higgs recently discovered at CERN has not been established yet. One intriguing possibility is that it may arise as a light composite state from a confining dynamics at the TeV scale. I will review the recent progress in understanding the dynamics that may be behind this mechanism, focusing on what we can learn by knowing its details. The masses of the spin-1 resonances can in fact be extracted from lattice calculations thus providing an estimate of the mass scale of new states. Furthermore, a lot can be learned about the physics of eventual top partners.

The search for new physics at the TeV scale is one of the major aspects of the CMS experimental program. This includes a myriad of theoretical models involving resonances that can decay to massive bosons, leptons or jets. An overview of such analyses is presented in this paper as well as the novel dedicated techniques related to the specificity of the event topologies. All analyses presented here use the full 2012 dataset, corresponding to an integrated luminosity of ∼ 20 fb⁻¹ recorded in proton-proton collisions at √s = 8 TeV with the CMS detector at the CERN LHC.

Vector-like quarks are an essential ingredient of many extensions of the Standard Model of particle physics. Moreover the presence of more than one vector-like multiplet is a common situation in many models. The interplay of these vector-like multiplet with precision electroweak bounds, flavour and collider phenomenology, especially at the Large Hadron Collider is a important point for the discovery of physics beyond the standard model. I consider the presence of two vector-like multiplets in order to show the constraints on such scenarios from tree-level data and oblique corrections in the case of a completely general flavour mixings with all the three standard model families of quarks. I also describe a framework for studying the interplay of any number of vector-like multiplets.

The rapidity distribution and longitudinal energy distribution are analysed within the thermodynamical formalism with the non-extensive Tsallis statistics. Our approach is based on a model for fireball rapidity distribution recently proposed where the fireball moves longitudinaly according to a q-Gaussian function rapidity distribution. We show that the rapidity distribution of charged hadrons are correctly obtained as compared to the experimental data for rapidities up to ∼ 10.5. The energy density as a function of the rapidity is studied for the first time. We show that most of the energy carried by hadrons are in the high rapidity region. Our results show that the energy density is a good tool for studying the logitudinal aspects of high energy collisions.

The data recorded by the Compact Muon Solenoid experiment during the first LHC run (2010-2012) has allowed to refine our knowledge on the production of jets and vector boson using the proton-proton collisions at √s = 7 or 8 TeV. Representative studies concerning the PDF and as extractions, the study of inclusive vector boson production, of production vector bosons in association with jets, and some recent results on anomalous gauge couplings evaluation are discussed.

Measurements of the top-quark mass and other top-quark properties are presented, obtained from the CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV. The mass of the top quark is measured using several methods and decay channels. The measurements of the top-quark properties include the W helicity in top-quark decays, the search for anomalous couplings, and the ratio of top-quarks decaying to bW over qW in order to gain information on |V_tb| using both $t\bar t$ and single-top quark event samples. The results are compared with predictions from the standard model as well as new physics models. The cross section of $t\bar t$ events produced in association with a W, Z boson or a photon is also measured.

In this talk we will summarize the main results from our recent work concerning the possibility that a new metastable phase occurs in some heavy ion collisions (HIC). This phase would be characterized by the breaking of two characteristic symmetries of strong interactions; namely P and CP. We investigate the experimental consequences of parity breaking in such a situation and propose suitable observables to elucidate the presence this phenomenon.

One of the most alluring models used to probe Beyond the Standard Model physics in run-I at ATLAS stems from a simple extension of the Higgs sector. Models where the Higgs sector is assumed to have two Higgs doublets, known as two-Higgs-Doublet-Models (2HDMs), give rise to five Higgs bosons: two neutral CP-even (h,H) bosons, two charged (H^±) bosons, and one neutral CP-odd (A) boson. Direct searches for the additional Higgs bosons became an ever more promising prospect after the Higgs boson discovery, and various such searches have already been conducted in Run-I ATLAS data. The most recent 2HDM search is for the A boson in the sensitive Zh decay, where h is assumed to be the LHC discovered Higgs boson, within the mass range of 220 — 1000 GeV. In such a search, upper limits on the cross section times branching ratio of the A boson decaying to Zh are set for various 2HDM scenarios. Where no excess is observed, exclusion limits are set on ranges of the 2HDM phase-space. In this note the search for A → Zh → ℓℓττ with fully hadronic tau decay is presented in detail, along with summaries from two of the most recent 2HDM searches in ATLAS.

The ATLAS Tile hadronic calorimeter (TileCal) provides highly-segmented energy measurements of incoming particles. It is a key detector for the measurement of hadrons, jets, tau leptons and missing transverse energy. It is also useful for identification and reconstruction of muons due to good signal to noise ratio. The calorimeter consists of thin steel plates and 460,000 scintillating tiles configured into 5000 cells, each viewed by two photomultipliers. The calorimeter response and its readout electronics is monitored to better than 1% using radioactive source, laser and charge injection systems. The calibration and performance of the calorimeter have been established through test beam measurements, cosmic ray muons and the large sample of proton-proton collisions acquired in 2011 and 2012. Results on the calorimeter performance are presented, including the absolute energy scale, timing, noise and associated stabilities. The results demonstrate that the Tile Calorimeter has performed well within the design requirements and it has given essential contribution to reconstructed objects and physics results. In addition, the data quality procedures used during the LHC data-taking are described and the outcome of the detector consolidation in the maintenance period is also presented.

Improvements to heavy and light flavor energy loss models based on strong-coupling physics in quark-gluon plasma lead to qualitative agreement between the models and data from RHIC and LHC within the regimes of applicability of the calculations. Thus it is possible to describe self-consistently the dynamics of quark-gluon plasma from the lowest observed momentum modes to the highest from the AdS/CFT correspondence.

The radiation damage in polyvinyl toluene based plastic scintillator EJ200 obtained from ELJEN technology was investigated. This forms part of a comparative study conducted to aid in the upgrade of the Tile Calorimeter of the ATLAS detector during which the Gap scintillators will be replaced. Samples subjected to 6 MeV proton irradiation using the tandem accelerator of iThemba LABS, were irradiated with doses of approximately 0.8 MGy, 8 MGy, 25 MGy and 80 MGy. The optical properties were investigated using transmission spectroscopy whilst structural damage was assessed using Raman spectroscopy. Findings indicate that for the dose of 0.8 MGy, no structural damage occurs but a breakdown in the light transfer between base and fluor dopants is observed. For doses of 8 MGy to 80 MGy, structural damage leads to hydrogen loss in the benzene ring of the PVT base which forms free radicals. This results in an additional absorptive component causing increased transmission loss as dose is increased.

The measurement of the triple Higgs boson coupling is one of the most important goals of the Higgs physics program in present and future collider experiments. This would provide the first direct information on the Higgs potential, which is responsible for electroweak symmetry breaking mechanism. We present a double Higgs production scenario at the Large Hadron-Electron Collider (LHeC) and Future Circular Hadron-Electron Collider (FCC- he) through e^-p collisions, which will provide information about trilinear coupling and the possibility of probing new physics, if there is any. The LHeC will provide e^- beams to collide head-on with proton beams of 7 TeV from the Large Hadron Collider (LHC). The prospect of replacing the LHC with the high energy FCC, with proton beams of 50 TeV, is used for FCC-he studies. Energy of the e^- is taken to be 60 GeV for both LHeC and FCC-he. Effects of non-standard CP-even and CP-odd couplings for hhh, hWW and hhWW have been studied and constrained at a 95% C.L.

Recent results from the ATLAS experiment at the LHC in the search for supersymmetry are presented. A focus is placed on searches requiring nonstandard techniques in particularly challenging final states. All searches presented here analyze pp collisions with √s = 8 TeV collected in 2012. Within these results, in the absence of significant disagreement from the Standard Model expectations, limits are placed on various models in both strong and weak sparticle production as well as on models with long-lived sparticles.

We use the Schwinger-Keldysh finite-time formalism applied to an interacting scalar field theory to derive perturbative expressions detailing the system which exists during the initial stages of a high energy collision. Further, we define the QFT conditional expectation value in an effort to describe the initial conditions associated with jet production in heavy ion physics.

In this paper we calculate 〈ϕ〉 (x) for a scalar Yukawa model, demonstrate the finiteness of the energy momentum tensor for λϕ⁴ to leading order, and derive an expression for the conditional expectation value of operators to aid in the description jet-like behaviour in interacting theories.

The property measurements of the recently discovered boson at a mass around 125 GeV confirm that it is compatible with the Higgs boson predicted by the Standard Model. Since the discovery and the first property measurements were performed using the bosonic decay channels, it is particularly important to observe and measure the Higgs boson using the fermionic decay channels. We present a review of the searches for the Higgs boson decaying to a pair of τ-leptons, muons, and b-quarks with the ATLAS experiment using LHC Run 1 full dataset.

We define a novel definition of the holographic light hadron jet by a separation of scales from plasma to jet, which leads to the re-emergence of the late-time Bragg peak in the instantaneous jet energy loss rate. We use the holographic energy loss of light quark and our new jet prescription in AdS/CFT to calculate the nuclear modification factor of jet for a brick of plasma (both static and expanding plasma) and compare the AdS/CFT results with the experimental data for most central Pb-Pb collision at LHC at 2.76 TeV center-of-mass energy. Defining a renormalized AdS/CFT jets that we argue better reflect QCD physics, we find a surprisingly good agreement between our toy model which is the first fully strongly coupled calculations, and preliminary jet suppression data from heavy ion collisions at LHC.

The LHCb detector and LHC running conditions are ideally suited to measure central exclusive production. Recent results of central exclusive production of J/Ψ, Ψ(2S) and double charmonium are presented. Results are consistent with theoretical expectations. Prospects for measurements of central exclusive production with a new detector installed for the next running period are discussed.

The forward acceptance of the LHCb detector allows it to probe proton-ion collision in a unique kinematic range, complementary to the other LHC experiments. The production of J/Ψ and ϒ-mesons decaying into two muons is studied at the LHCb experiment in proton-lead collisions at a proton-nucleon centre-of-mass energy = 5 TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 1.6 nb^-1. The nuclear modification factor and the forward-backward production ratio are determined for J/Ψ and ϒ(1S) mesons. Clear suppression of prompt J/Ψ production is observed with respect to the production in pp collisions at large rapidity, while the suppression of J/Ψ from b-hadron decays is less pronounced. The nuclear modification factor for ϒ(1S) mesons in the forward region is found to be similar to those for J/Ψ from b-hadron decays. Furthermore, a first observation of Z bosons in proton-lead collisions is reported.

The Large Hadron Collider at CERN is scheduled to undergo a major upgrade, called the Phase II Upgrade, in 2022. The ATLAS Tile Calorimeter (TileCal) community will do major modifications to the sub-detector to account for the increased luminosity. More specifically, a large proportion of the current front and back-end electronics will be upgraded in order to digitize all signals generated in the Calorimeters. A Demonstrator program has been established, which combines the current and future architectures, as a proof of principle. The insertion of the first demonstrator is planned for the end of 2015.

The combined analysis of the B⁰_s and B⁰ meson decays into two muons based on the full CMS and LHCb datasets is presented. The simultaneous fit to the datasets yields the most precise measurement of the branching fractions to date with a total uncertainty of about 23% for the B⁰_s meson and 38% for the B⁰ decay into two muons. The measured branching fractions are compatible with the Standard Model predictions within 1.2σ and 2.2σ for the B⁰_s and B⁰ signals, respectively. The statistical significance for the B⁰_s signal is 6.2σ and 3.2σ for the B⁰ signal. This results in the first observation of B⁰_s meson decays into two muons and the first evidence for the B⁰ sister decay.

To explore cosmic matter in the laboratory - this fascinating research prospect becomes available at the Facility for Antiproton and Ion Research, FAIR. The new facility is being constructed within the next five years adjacent to the existing accelerator complex of the GSI Helmholtz Centre for Heavy Ion Research at Darmstadt/Germany, expanding the research goals and technical possibilities substantially. This includes new insights into the dynamics of supernovae depending on the properties of short-lived neutron-rich nuclei which will be investigated with intense rare isotope beams. New insights will be provided into the interior of stars by exploring dense plasmas with intense heavy-ion beams combined with a high-performance laser - or into neutron star cores by probing the highest baryon densities in relativistic nucleus-nucleus collisions at unprecedented collision rates. To the latter, the properties of hadrons play an important part which will be systematically studied by high precision hadron spectroscopy with antiproton beams at unmatched intensities. The worldwide unique accelerator and experimental facilities of FAIR will open the way for a broad spectrum of unprecedented fore-front research supplying a large variety of experiments in hadron, nuclear, atomic and plasma physics as well as biomedical and material science which will be briefly described in this article. This article is based on the FAIR Green Paper [4] and gives an update of former publications [5] - [12].

The NA61/SHINE experiment performs a detailed study of the onset of deconfinement and search for critical point of hadronic matter by colliding nuclei of different sizes at various beam momenta from 13A to 158A GeV/c. Experimental setup and results on the theoretically expected signatures are discussed.

In the most important shift of paradigm of its membership rules in 60 years, CERN in 2010 introduced a policy of "Geographical Enlargement" which for the first time opened the door for membership of non-European States in the Organization. This short article reviews briefly the history of CERN's membership rules, discusses the rationale behind the new policy, its relationship with the emerging global roadmap of particle physics, and gives a short overview of the status of the enlargement process.

The CMS collaboration searched for Dark Matter (DM) particles produced in pairs in proton-proton (pp) collisions performed by the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 /fb. The following signatures were investigated: a single boosted object and a significant transverse momentum imbalance; associated production of DM with a pair of top quarks; decay of a Higgs boson (H) into a pair of DM particles. Exclusion limits were set on the cross sections of DM production and interaction cross sections, as a function of the DM particle mass.