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We present a summary of the first calculation of NLO QCD corrections to WZjj production with leptonic decays at the LHC. Our results show that the next-to-leading order corrections reduce significantly the scale uncertainties.
The Belle-II experiment and superKEKB accelerator will form a next generation B-factory at KEK, capable of running at an instantaneous luminosity 40 times higher than the Belle detector and KEKB. This will allow for the elucidation of many facets of the Standard Model by performing precision measurements of its parameters, and provide sensitivity to many rare decays that are currently inaccessible. This will require major upgrades to both the accelerator and detector subsystems. The imaging Time-of-propagation (iTOP) detector will be a new subdetector of Belle-II that will perform an integral role in Particle identification (PID). It will comprise 16 modules between the tracking detectors and calorimeter; each module consisting of a quartz radiator, approximately 2.5m in length, instrumented with an array of 32 micro-channel plate photodetectors (MCP-PMTs). The passage of charged particles through the quartz will produce a cone of Cherenkov photons that will propagate along the length of the quartz, and be detected by the MCP-PMTs. The excellent spatial, and timing resolution (of 50 picoseconds) of the iTOP system will provide superior particle identification capabilities, particularly allowing for enhanced discrimination between pions and kaons that will be essential for many of the key measurements to performed. The status of the construction of the iTOP subdetector, and performance studies of prototypes at beam tests will be presented, together with prospects for physics measurements that will utilise the PID capabilities of the iTOP system.
We present the current status for the measurements of the ttbar charge asymmetry at the Tevatron and LHC colliders.
Detector rate capability is one of the main parameters for designing a new detector for high energy physics due to permanent rise of the beam luminosity of modern accelerators. One of the widely used detectors for particle track reconstruction is a straw detector based on drift tubes. The rate capability of such detectors is limited by the parameters of readout electronics. The traditional method of increasing detector rate capability is increasing their granularity (a number of readout channels) by reducing the straw diameter and/or by dividing the straw anode wire into two parts (for decreasing the rate per readout channel). A new method of designing straw detectors with a high rate capability is presented and tested. The method is based on dividing the straw cathode into parts and independent readout of each part.
Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the HERMES experiment. The asymmetries were studied as a function of the azimuthal angle $ψ$ about the beam direction between the target-spin direction and the hadron production plane, the transverse hadron momentum relative to the direction of the incident beam, and the Feynman variable $x_F$. The $\sin(ψ)$ amplitudes are positive for positive pions and kaons, slightly negative for negative pions and consistent with zero for negative kaons, with particular transverse-momentum but weak $x_F$ dependences. Especially large asymmetries are observed for two small subsamples of events, where also the scattered electron was recorded by the spectrometer.
In these proceedings I cover the latest results on the production and decay of the recently discovered Higgs boson. While the spin and properties of the new boson, such as its mass and couplings to bosons and fermions, are covered in a separate report, I focus on individual results in the main channels we use to study the properties of the new boson and to search for its possible cousins, with the focus on the latest results from the LHC and the Tevatron collaborations.
Quark flavour conserving (QFC) fermionic squark decays, such as ~t_{1,2} -> t neutralino_i, are usually assumed in squark search analyses. Here we study quark flavour violating (QFV) bosonic squark decays, such as ~u_2 -> ~u_1 h^0/Z^0, where the mass eigenstates ~u_{1,2} are mixtures of scharm and stop quarks. We show that the branching ratios of such QFV decays can be very large due to sizable ~c_R - ~t_{R/L} and ~t_R - ~t_L mixing effects despite the very strong constraints on the QFV parameters from B meson data. This can result in remarkable QFV signatures with significant rates at LHC (14 TeV), such as pp -> gluino gluino X -> t c bar{c} bar{c} h^0/Z^0 missing-E_T X and pp -> gluino gluino X -> t t bar{c} bar{c} h^0/Z^0 missing-E_T X. The QFV bosonic squark decays can play an important role in the squark and gluino searches at LHC (14 TeV).
In these proceedings, we give a summary of the experimental results from CLEO, Belle, BaBar and CDF collaboration about $D^0-\bar{D}^0$ mixing and CP violation in self-conjugated-three-body decays $D^0\rightarrow K_S^0hh$ (where $h$ can be $π$ or $K$). We report preliminary results of measurement of $D^0-\bar{D}^0$ mixing and indirect CP violation in $D^0\rightarrow K_S^0π^+π^-$ decays using full data sample collected by Belle detector at KEKB asymmetric-energy $e^+e^-$ collider: give values for $x=(0.56\pm0.19^{+0.03+0.06}_{-0.09-0.09})%$, $y=(0.30\pm0.15^{+0.04+0.03}_{-0.05-0.06})%$, $|q/p|=0.90^{+0.16+0.05+0.06}_{-0.15-0.04-0.05}$ and $\arg(q/p)=-6\pm11^{+3+3}_{-3-4}(^o)$. We also report results of recent measurement searching for CP violation in $D^0\rightarrow K_S^0π^+π^-$ decays by CDF collaboration using $6.0 fb^{-1}$ of data collected in $p\bar{p}$ collisions at Tevatron. The phase-space-integrated CP asymmetry is measured to be $A_{CP}=(-0.05\pm0.57\pm0.54)%$ and the CP symmetry is also found to be conserved in all individual intermediate contributions.
The opportunities which are offered by a next generation and multi-purpose fixed-target experiment exploiting the proton and lead LHC beams extracted by a bent crystal are outlined. In particular, such an experiment can greatly complement facilities with lepton beams by unraveling the partonic structure of polarised and unpolarised nucleons and of nuclei, especially at large momentum fractions.
We discuss coherent and incoherent photoproduction of $J/Ψ$ vector mesons in high energy heavy ion collisions. In a dipole picture for the photon both can be naturally related to the dipole cross section that is also probed in inclusive DIS. We compare results of a particular calculation to ALICE data.
We present an informal discussion of some aspects of strong interactions under extreme conditions of temperature and density at an elementary level. This summarizes lectures delivered at the 2013 CERN -- Latin-American School of High-Energy Physics and is aimed at students working in experimental high-energy physics.
The primary goal of the Long-Baseline Neutrino Experiment (LBNE) is to measure the neutrino mixing matrix parameters. The design, optimized to search for CP violation and to determine the neutrino mass hierarchy, includes a large $\mathcal{O}(10$ kt) Liquid Argon Time Projection Chamber (LAr TPC) at 1300 km downstream of a wide-band neutrino beam. A brief introduction to the neutrino mixing parameters will be followed by a discussion of sensitivity study analysis methods and a summary of the results for LBNE. The studies include comparisons with the Tokai-to-Kamioka (T2K) and NuMI Off-axis electron-neutrino Appearance (NO$ν$A) experiments as well as combined sensitivities. Finally, the impact of including a realistic set of systematic uncertainties will be presented.
The Intensity Frontier (IF) is a primary focus of the U.S.-based particle physics program. It encompasses a large spectrum of physics, including quark flavor physics, charged lepton processes, neutrinos, baryon number violation, new light weakly-coupled particles, and nucleons, nuclei and atoms. There are many experiments, a range of scales in data output and throughput, and a wide range in the number of experimenters. The experiments, projects and theory in this area all require demanding computing capabilities and technologies. The IF experiments have significant computing requirements for simulation, theory and modeling, beam line and experiment design, triggers and DAQ, online monitoring, event reconstruction and processing, and physics analysis. We have conducted a qualitative survey of the current and near-term future experiments in the IF to understand the computing demands of this area and their expected evolution. This report details the expected computing requirements for the IF in the context of the Snowmass Community Summer Study 2013.
The field of neutrino physics was covered at DPF 2013 in 32 talks, including three on theoretical advances and the remainder on experiments that spanned at least 17 different detectors. This summary of those talks cannot do justice to the wealth of information presented, but will provide links to other material where possible. There were allso two plenary session contributions on neutrino physics at this meeting: the current status of what we know about neutrino (oscillation) physics was outlined by Huber, and the next steps in long baseline oscillation expeirments were described by Fleming. This article covers a subset of the topics discussed at the meeting, with emphasis given to those talks that showed data or new results.
With RHIC running in its second phase at higher luminosities the new data sets collected so far by PHENIX and STAR are allowing improvements in the study of vector meson photo-production in Ultra peripheral Collision events in Au+Au at the highest energy. This is a brief summary of what has been accomplished so far by both collaborations.
I give a personal overview of some highlights of the EDS Blois 2013 Conference on elastic and diffractive scattering in Saariselka, Finland.
The data on the diffractive deep inelastic scattering (DDIS) at HERA exhibit a strong excess, up to about 100%, above the twist-two NLO DGLAP description at low $Q^2$ and at large energy. I show, that complementing the DGLAP fit by twist 4 and 6 components of the saturation model leads to a good description of data at low $Q^2$ and conclude that the DDIS at HERA provides the first evidence of higher twist effects in DIS.
We carry out a series of studies on pion and photon productions in neutrino/electron/photon--nucleus scatterings. The low energy region is investigated by using a chiral effective field theory for nuclei. The results for the neutral current induced photon production ($γ$-NCP) are then extrapolated to neutrino energy $E_ν\sim$ GeV region. By convoluting the cross sections with MiniBooNE's beam spectrum and detection efficiency, we estimate its $γ$-NCP, event number, and conclude that such photon production can not fully explain its low energy event excess in both neutrino and antineutrino runs.