International Journal of Modern Physics: Conference Series

We present the most recent precision electroweak measurements of single W and Z boson cross section and properties from the LHC and Tevatron colliders, analyzing data collected by ATLAS, CDF, CMS, D0, and LHCb detectors. The results include the measurement of the single W and Z boson cross section at LHC, the differential cross section measurements, the measurement of W boson mass, the measurement of W and Z charge asymmetry. These measurements provide precision tests on the electroweak theory, high order predictions and the information can be used to constraint parton distribution functions.

This paper summarizes top quark cross-section measurements at the Tevatron and the LHC. Top quark pair production cross-sections have been measured in all decay modes by the ATLAS and CMS collaborations at the LHC and by the CDF and D0 collaborations at the Tevatron. Single top quark production has been observed at both the Tevatron and the LHC. The t-channel and associated Wt production modes have been observed at the LHC and evidence for s-channel production has been reported by the Tevatron collaborations.

Almost two decades after its discovery at Fermilab's Tevatron collider experiments, the top quark is still under the spotlight due to its connections to some of the most interesting puzzles in the Standard Model. The Tevatron has been shut down two years ago, yet some interesting results are coming out of the CDF and D0 collaborations. The LHC collider at CERN produced two orders of magnitude more top quarks than Tevatron's, thus giving birth to a new era for top quark physics. While the LHC is also down at the time of this writing, many top quark physics results are being extracted out of the 7 TeV and 8 TeV proton proton collisions by the ATLAS and CMS collaborations, and many more are expected to appear before the LHC will be turned on again sometime in 2015. These proceedings cover a selection of recent results produced by the Tevatron and LHC experiments.

This is a report at the conference Physics In Collision 2013. The experimental results on physics of diboson production are reviewed. The measurements use pp collision at the LHC with center-of-mass energy and 8 TeV, and collision at the Tevatron with . These include measurements of Wγ, Zγ, WW, WZ and ZZ production. The results are compared with Standard Model predictions, and are interpreted in terms of constraints on charged and neutral anomalous triple gauge couplings.

The "proton structure" is a wide field. Discussed are predominantly the precision measurements of the proton structure functions at HERA and some of their implications for the LHC measurements. In addition, a discussion of what a proton structure function represents is provided. Finally, a connection to nuclear physics is attempted. This contribution is an updated reprint of a contribution to "Deep Inelastic Scattering 2012".¹

In this talk we summarize some recent developments in perturbative QCD and their application to particle physics phenomenology.

Recent Lattice QCD results are reviewed with an emphasis on spectroscopic results concerning the charm quark. It is demonstrated that, with accurate computations from lattice QCD in recent years that can be compared with the existing or upcoming experiments, stringent test of the Standard Model can be performed which will greatly sharpen our knowledge on the strong interaction.

Neutrinos are elementary particles in the standard model of particle physics. There are three flavors of neutrinos that oscillate among themselves. Their oscillation can be described by a 3×3 unitary matrix, containing three mixing angles θ₁₂, θ₂₃, θ₁₃, and one CP phase. Both θ₁₂ and θ₂₃ are known from previous experiments. θ₁₃ was unknown just two years ago. The Daya Bay experiment gave the first definitive non-zero value in 2012. An improved measurement of the oscillation amplitude and the first direct measurement of the mass-squared difference were obtained recently. The large value of θ₁₃ boosts the next generation of reactor antineutrino experiments designed to determine the neutrino mass hierarchy, such as JUNO and RENO-50.

A review of ν_e appearance oscillation experiments is presented. The measurement of the appearance signal is of particular interest because this mode is sensitive to both θ₁₃, δ_CP and other mixing parameters. Using the value of θ₁₃ measured by reactor neutrino experiments (disappearance studies) present and next generation appearance experiments can explore CP violation.

Low energy neutrino investigation has been one of the most active fields of particle physics research over the past decades, accumulating important and sometimes unexpected achievements. In this work some of the most recent impressive successes will be reviewed, as well as the future perspectives of this exciting area of study.

Neutrinoles double beta decay is the only process known so far able to test the neutrino intrinsic nature: its experimental observation would imply that the lepton number is violated by two units and prove that neutrinos have a Majorana mass components, being their own anti-particle. While several experiments searching for such a rare decay have been performed in the past, a new generation of experiments using different isotopes and techniques have recently released their results or are raking data and will provide new limits, should no signal be observed, in the next few years to come. The present contribution reviews the latest public results on double beta decay searches and gives an overview on the expected sensitivities of the experiments in construction which will be able to set stronger limits in the near future.

The newly discovered boson was only observed in diboson final states. The measurement of the fermionic decay modes of this new particle is essential to establish its compatibility with the Standard Model Higgs boson. The two main final states accessible at the LHC are the decay into pairs of b quarks and τ leptons, both of which are experimentally challenging. In some cases, the exploitation of specific Higgs boson production modes allows to significantly increase the experimental sensitivity. One can also extend the search by looking for di-muon final states. This article gives an overview of the Higgs boson searches in these three fermionic final states at the ATLAS and CMS experiments, focusing on the most recent developments and results.

While the existence of a Higgs boson with a mass near 125 GeV has been clearly established, the detailed structure of the entire Higgs sector is yet unclear. Besides the Standard Model interpretation, various possibilities for extended Higgs sectors are being considered. The minimal supersymmetric extension (MSSM) features two Higgs doublets resulting in five physical Higgs bosons, which are subject to direct searches. Alternatively, more generic Two-Higgs Doublet models (2HDM) are used for the interpretation of results. The Next-to-Minimal Supersymmetric Model (NMSSM) has a more complex Higgs sector with seven physical states. Also exotic Higgs bosons decaying to invisible final states are considered. This article summarizes recent findings based on results from collider experiments.

The new particle recently discovered at the Large Hadron Collider has properties compatible with those expected for the Standard Model (SM) Higgs boson. However, this does not exclude the possibility that the discovered state is of non-standard origin, as part of an elementary Higgs sector in an extended model, or not at all a fundamental Higgs scalar. We review briefly the motivations for Higgs boson scenarios beyond the SM, discuss the phenomenology of several examples, and summarize the prospects and methods for studying interesting models with non-standard Higgs sectors using current and future data.

A review of B and B_s decays is presented. Emphasis is given to processes most sensitive to physics beyond the Standard Model, such as radiative, electroweak and "Higgs" penguin decays, and tree-level decays involving tau leptons in the final state. An outlook on future perspectives is also given.

An overview of selected recent results on mixing and CP-symmetry violation in the charm sector, and D meson rare decays, was presented at the Physics In Collision conference 2013 in Beijing.

In this report I review some results on the charmonium and light hadron spectroscopy mainly from BESIII and Belle experiments. For the charmonium, the contents include the observation of ψ(4040)/ψ(4160) → ηJ/ψ, the measurements of the η_c/η_c(2S) resonance parameters and their decays, the evidence of the ψ₂(1³D₂) state in the χ_c1γ mass spectrum. For the light hadron spectroscopy, the contents include the X(1835) research in e⁺e^- → J/ψ + X(1835) and γγ → η′π⁺π^- processes, and the analysis of the ηη, ωϕ, ϕϕ and ωω mass spectra in low mass region.

A number of charmonium-(bottomonium-)like states have been observed in B-factory experiments. Recently the BESIII experiment has joined this search with a unique data sample collected at the different center of mass energies ranging from 3.9 GeV to 4.42 GeV in which they found new charmonium-like states with non-zero electric charge. We review the status of experimental searchs for quarkonium-like states and also other types of non- meson or non-qqq baryons that are predicted by QCD-motivated models. We mainly focus on results from the B-factories and BESIII.

These proceedings discuss results from recent searches for third generation SUSY particles by the ATLAS and CMS experiments at the LHC. Analyses performed with 8 TeV data probing direct pair production of bottom and top squarks are presented.

We report on the operation and performance of the ATLAS Semi-Conductor Tracker (SCT), which has been functioning for 3 years in the high luminosity, high radiation environment of the Large Hadron Collider at CERN. We also report on the few improvements of the SCT foreseen for the high energy run of the LHC. We find 99.3% of the SCT modules are operational, the noise occupancy and hit efficiency exceed the design specifications; the alignment is very close to the ideal to allow on-line track reconstruction and invariant mass determination. We will report on the operation and performance of the detector including an overview of the issues encountered. We observe a significant increase in leakage currents from bulk damage due to non-ionizing radiation and make comparisons with the predictions.

This paper gives an overview of the performance of the Tile Calorimeter of the ATLAS detector at the Large Hadron Collider. Detector performances with respect to electronic noise and cell response are presented. In addition, an overview of the partially overlapping calibration systems is given.

The CMS experiment has been designed with a 2-level trigger system: the Level 1 Trigger, implemented on custom-designed electronics, and the High Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm. A software trigger system requires a tradeoff between the complexity of the algorithms running on the available computing power, the sustainable output rate, and the selection efficiency. Here we will present the performance of the main triggers used during the 2012 data taking, ranging from simpler single-object selections to more complex algorithms combining different objects, and applying analysis-level reconstruction and selection. We will discuss the optimisation of the triggers and the specific techniques to cope with the increasing LHC pile-up, reducing its impact on the physics performance.

An end-cap Time-of-Flight (E-TOF) system with higher granularity and intrinsic time resolution of better than 50 ps will extend the K/pion separation (2 sigma) pT range to 1.4 GeV/c and enhance the physics capability of Beijing Spectrometer (BESIII). A R&D work was carried out aiming at upgrading the current BESIII E-TOF with the Multi-gap resistive Plate Chamber (MRPC) detector. The latest best test for the prototype MRPC, together with the custom designed Front End Electronics (FEE) and TDC boards, was performed at the BEPC E3 line in July 2012. The test results show that time resolution of less than 50 ps can be achieved with such a system.

Double Chooz is a long baseline neutrino oscillation experiment at Chooz, France. The purpose of this experiment is to measure the non-zero neutrino oscillation parameter θ₁₃, a parameter for changing electron neutrinos into other neutrinos. This experiment uses reactors of the Chooz Nuclear Power Plant as a neutrino source. Double Chooz has published two papers with results showing the measurement of the mixing angle, and 3rd publication is processing.

The medium baseline reactor antineutrino experiment, Jiangmen Underground Neutrino Observatory (JUNO), which is being planned to be built at Jiangmen in South China, can determine the neutrino mass hierarchy and improve the precision of three oscillation parameters by one order of magnitude. The sensitivity potential on these measurements is reviewed and design concepts of the central detector are illustrated. Finally, we emphasize on the technical challenges we meet and the corresponding R&D efforts.

Astroparticles offer a new path for research in the field of particle physics, allowing investigations at energies above those accesible with accelerators. Ultra-high energy cosmic rays can be studied via the observation of the showers they generate in the atmosphere. The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays, combining two complementary measurement techniques used by previous experiments, to get the best possible measurements of these air showers. Shower observations enable one to not only estimate the energy, direction and most probable mass of the primary cosmic particles but also to obtain some information about the properties of their hadronic interactions. Results that are most relevant in the context of determining hadronic interaction characteristics at ultra-high energies will be presented.

The COherent Muon to Electron Transition (COMET) experiment aims to search for the charged-lepton-flavor-violating process through measure muon to electron conversion in a muonic atom to very high sensitivity of 2.6 × 10^-17. A two-stage approach in order to realize the experiment has been taken and the first-stage (COMET Phase-I) has been approved by KEK.

A search for the Standard Model Higgs Boson decaying into τ pairs is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. An excess of events is observed over a broad range of Higgs mass hypotheses, with a maximum local significance of 2.93 standard deviations at m_H = 120 GeV. The excess is compatible with the presence of a standard-model Higgs boson of mass 125 GeV/c².

My report consists of two parts: (1). Using samples of 102 million ϒ(1S) and 158 million ϒ(2S) events at Belle, we study 17 exclusive hadronic decays of these two bottomonium resonances to some Vector-Pseudoscalar (VP), Vector-Tensor (VT) and Axial-vector-Pseudoscalar (AP) processes and their final states. Branching fractions are measured for all the processes. The ratios of the branching fractions of ϒ(2S) and ϒ(1S) decays into the same final state are used to test a perturbative QCD (pQCD) prediction for OZI-suppressed bottomonium decays. (2). Using data samples of 89 fb^-1, 703 fb^-1, and 121 fb^-1 collected at center-of-mass (CMS) energies 10.52, 10.58, and 10.876 GeV, respectively, we measure the cross sections of e⁺e^- → ωπ⁰, , and . The energy dependence of the cross sections is presented.

Based on 2.92 fb^-1 of e⁺e^- collision data collected with the BESIII detector at GeV, we measured the asymmetry of the branching fractions of D^CP± → K^-π⁺ (D^CP± are the CP-odd and CP-even eigenstates) to be . is used to extract the strong phase difference δ_Kπ between the doubly Cabibbo-suppressed process and Cabibbo-favored D⁰ → K^-π⁺. By taking inputs of other parameters in world measurements, we obtain cosδ_Kπ = 1.03 ± 0.12 ± 0.04 ± 0.01. This is the most accurate result of cosδ_Kπ to date and can improve the world constrains on the mixing parameters and on γ/ϕ₃ in the CKM matrix.

The BESIII experiment in Beijing takes data in τ-charm domain since 2009. For the moment the world largest samples of J/ψ, ψ(3686), ψ(3770) and ψ(4040) data have been collected. Hadron spectroscopy is a unique way to access QCD, which is one of the most important physics goals of BESIII. Experimental search of new forms of hadrons and subsequent investigation of their properties would provide validation of and valuable input to the quantitative understanding of QCD. The key to success lies in high levels of precision during the measurement and high statistics in the recorded data set complemented with sophisticated analysis methods. Partial wave analysis (PWA) is a powerful tool to study the hadron spectroscopy, that allows one to extract the resonance's spin-parity, mass, width and decay properties with high sensitivity and accuracy. In this poster, we present the working PWA framework of BESIII – GPUPWA and the recent results of PWA of J/ψ → γηη. GPUPWA is a PWA framework for high statistics partial wave analyses harnessing the GPU parallel computing.

Using data samples collected with the BESIII detector operating at the BEPCII storage ring at central-of-mass (CM) energies from 4.009 to 4.420 GeV, the e⁺e^- → γX(3872) process is observed with a statistical significance of more than 5σ. The measured mass is in agreement with previous measurements. The products of cross section of e⁺e^- → γX(3872) and the branching fraction at CM energies 4.009, 4.229, 4.260, and 4.360 GeV is reported. The results support the possibility that Y(4260) → γX(3872).

The Kaon physics program at CERN will be shortly presented, addressing the most recent results from the NA48/2 and NA62 experiments at the CERN SPS and future prospects.

Due to the beam related background, the inner chamber of BESIII MDC has aging effect after 5 years running. The gains of the inner chamber cells decrease obviously, and the max gain decrease is about 26% for the first layer cells. A new inner drift chamber with eight stereo sense wire layers as a backup for MDC is under construction, which is almost the same as the current one but using stepped endplates to shorten the wire length beyond the effective solid angle. This new structure will be of benefit to reducing the counting rate of single cell. The manufacture of each component is going smoothly, and the new inner drift chamber will be finished by the end of April 2014.

Muon induced neutrons and long-lived radioactive isotopes are important background sources for low-energy underground experiments. We study the produced processes and properties of cosmic muon induced backgrounds, show the muon veto system used for rejecting these backgrounds and the methods to estimate residual backgrounds in the Daya Bay Reactor Neutrino Experiment.

Observation of the X(1840) in the 3(π⁺π^-) invariant mass in J/ψ → γ3(π⁺π^-) at BESIII is reviewed. With a sample of 225.3 × 10⁶J/ψ events collected with the BESIII detector at BEPCII, the X(1840) is observed with a statistical significance of 7.6σ. The mass, width and product branching fraction of the X(1840) are determined. The decay η′ → 3(π⁺π^-) is searched for, and the upper limit of the branching fraction is set at the 90% confidence level.

The Daya Bay Reactor Neutrino Experiment has measured a non-zero value of the neutrino mixing angle θ₁₃ with a significance of 7.7 standard deviations by a rate-only analysis.¹ The distortion of neutrino energy spectrum carries additional oscillation information and can improve the sensitivity of θ₁₃ as well as measure neutrino mass splitting . A rate plus shape analysis is performed and the results have been published.² Understanding detector energy non-linearity response is crucial for the rate plus shape analysis. In this contribution, we present a brief description of energy non-linearity studies at Daya Bay.