1321352
Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy.
A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 fb(-1) produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.
10401636
Search for di-muon decays of a low-mass Higgs boson in radiative decays of the Υ(1S)
We search for di-muon decays of a low-mass Higgs boson (A^0) produced in radiative Υ(1S) decays. The Υ(1S) sample is selected by tagging the pion pair in the Υ(2S,3S) → π^+ π^-Υ(1S) transitions, using a data sample of 92.8 × 10^6 Υ(2S) and 116.8 × 10^6 Υ(3S) events collected by the BABAR detector. We find no evidence for A^0 production and set 90% confidence level upper limits on the product branching fraction B(Υ(1S) → γA^0) × B(A^0 → μ^ +μ^-) in the range of (0.28-9.7) × 10^(-6) for 0.212 ≤ m_A^0 ≤ 9.20  GeV/c^2. The results are combined with our previous measurements of Υ(2S,3S) → γA^0, A^0 → μ^+μ^- to set limits on the effective coupling of the b quark to the A^0.
110632418
The BABAR detector: Upgrades, operation and performance
The BaBar detector operated successfully at the PEP-II asymmetric e +e- collider at the SLAC National Accelerator Laboratory from 1999 to 2008. This report covers upgrades, operation, and performance of the collider and the detector systems, as well as the trigger, online and offline computing, and aspects of event reconstruction since the beginning of data taking.
2621524
Study of the mass and spin-parity of the Higgs boson candidate via its decays to Z boson pairs.
A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb(-1), collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or μ pairs, is 126.2 ± 0.6(stat) ± 0.2(syst) GeV. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis.
122803232
Search for Microscopic Black Hole Signatures at the Large Hadron Collider
A search for microscopic black hole production and decay in pp collisions at a center-of-mass energy of 7 TeV has been conducted by the CMS Collaboration at the LHC, using a data sample corresponding to an integrated luminosity of 35 inverse picobarns. Events with large total transverse energy are analyzed for the presence of multiple high-energy jets, leptons, and photons, typical of a signal expected from a microscopic black hole. Good agreement with the expected standard model backgrounds, dominated by QCD multijet production, is observed for various final-state multiplicities. Limits on the minimum black hole mass are set, in the range 3.5 -- 4.5 TeV, for a variety of parameters in a model with large extra dimensions, along with model-independent limits on new physics in these final states. These are the first direct limits on black hole production at a particle accelerator.
10609473
Precise measurement of the e+e- --> pi+pi-(gamma) cross section with the initial state radiation method at BABAR.
A precise measurement of the cross section of the process e(+)e(-) --> pi(+)pi(-)(gamma) from threshold to an energy of 3 GeV is obtained with the initial state radiation (ISR) method using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e(+)e(-) --> mu(+)mu(-)gamma(gamma). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the pipi cross section measured from threshold to 1.8 GeV is (514.1 +/- 2.2(stat) +/- 3.1(syst)) x 10(-10).
123410881
Test of the hadronic interaction models at around *10 TeV with Tibet EAS core data
A hybrid experiment has been started by ASγ collaboration at Tibet, China, since May 2009, that consists of a burst-detector-grid (YAC, Yangbajing Air shower Core array) and the Tibet air-shower array (Tibet-III). The first step of YAC, called YAC-I, contains 16 detector units and observes high energy electromagnetic particles in air-shower cores within several meters from the shower axis, and Tibet-III array measures the total energy and the arrival direction of air showers. YAC-I is used to check hadronic interaction models currently used for air-shower simulations such as QGSJET, SIBYLL , EPOS etc. through the multi-parameter measurement in air-shower cores. In this paper, we used a data set collected from May 1st 2009 through February 23rd 2010 by the YAC-I. The effective live time used for the present analysis is 169.65 days. The preliminary results of the interaction model checking at *10 TeV energy region is reported in this paper.
109503383
Introduction to BESIII EMC sub-trigger system
Abstract The Electromagnetic Calorimeter (EMC) sub-trigger system is one of the important parts of the trigger system of the BESIII spectrometer. Together with the conditions from the other sub-trigger systems, cluster-related and energy-related trigger conditions are provided to the Global Trigger system for effective selection of events interested and rejection of backgrounds. Total two types of PCB boards are designed to implement the whole functions, which are Trigger Cell and energy Block Adding (TCBA) and Energy Adding and Cluster Counting (EACC). Simulations and hardware arrangement of the EMC sub-trigger system are introduced in this paper.
118582101
Fostering the adoption of GRID techniques: The case of the astroparticle physics experiment ARGO
The EUChinaGRID project is a FIX-funded initiative within the 6th Framework Programme, aiming at, disseminating advanced knowledge in Grid technologies, interconnecting the European and Chinese e-Infrastructures, and deploying existing and new Grid applications: the astroparticle physics experiment ARGO is One such application. This document will describe the strategy for the adoption of Grid techniques for data-manipulation activities within the ARGO experiment.
53364111
Proton-air cross section measurement with the ARGO-YBJ cosmic ray experiment
The proton-air cross section in the energy range 1-100 TeV has been measured by the ARGO-YBJ cosmic ray experiment. The analysis is based on the primary cosmic ray flux attenuation for different atmospheric depths (i.e. zenith angles) and exploits the detector capabilities of selecting the shower development stage by means of hit multiplicity, density and lateral profile measurements at ground. The effects of shower fluctuations, the contribution of heavier primaries and the uncertainties of the hadronic interaction models, have been taken into account. The results have been used to estimate the total proton-proton cross section at center-of-mass energies between 70 and 500 GeV, where no accelerator data are currently available.
124551811
The forward particle production in the energy range of 1 PeV as seen with the Tibet hybrid experiment
We are now operating the 500 m Yangbajing air-shower core (YAC-II) array near the center of the Tibet air-shower array ( Tibet-III ) to observe cosmic-ray chemical composition at the knee energy region since February 2011. The first step of YAC, called YAC-I, containing 16 detector units, was operated from May, 2009 to February, 2010. In this paper, we used the YAC-I and Tibet-III coincident data set obtained from May, 2009 through January, 2010 to present the electromagnetic spectrum of air shower cores at around 10 eV energy region. The effective live time is calculated as 100.5 days. We would like to report the comparison of our experimental data with MC model prediction in this paper.