119852910
Measurement of the mass difference between top and anti-top quarks in pp collisions at √s = 7 TeV using the ATLAS detector
A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb(-1) data sample of proton-proton collisions at root s = 7 TeV recorded with the ATLAS detector at the ...
109931424
Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC
Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H --> gamma-gamma, H --> ZZ* --> 4 leptons and H --> WW --> 2 leptons + 2 neutrinos. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of about 25/fb. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson.
124472455
Search for diphoton events with large missing transverse momentum in 7 TeV proton-proton collision data with the ATLAS detector
A search for diphoton events with large missing transverse momentum has been performed using proton-proton collision data at is root s = 7 TeV recorded with the ATLAS detector, corresponding to an integrated luminosity of 4.8 fb(-1). No excess of events was observed above the Standard Model prediction and model-dependent 95% confidence level exclusion limits are set. In the context of a generalised model of gauge-mediated supersymmetry breaking with a bino-like lightest neutralino of mass above 50 GeV, gluinos (squarks) below 1.07 TeV (0.87 TeV) are excluded, while a breaking scale Lambda below 196 TeV is excluded for a minimal model of gauge-mediated supersymmetry breaking. For a specific model with one universal extra dimension, compactification scales 1/R < 1.40 TeV are excluded. These limits provide the most stringent tests of these models to date. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
54998219
Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
A search for the Standard Model Higgs boson in proton–proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb−1 collected at View the MathML source in 2011 and 5.8 fb−1 at View the MathML source in 2012. Individual searches in the channels H→ZZ(⁎)→4l, H→γγ and H→WW(⁎)→eνμν in the 8 TeV data are combined with previously published results of searches for H→ZZ(⁎), WW(⁎), View the MathML source and τ+τ− in the 7 TeV data and results from improved analyses of the H→ZZ(⁎)→4l and H→γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of View the MathML source is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10−9, is compatible with the production and decay of the Standard Model Higgs boson.
121561502
Recent ATLAS results in the field of meson physics
Recent results on flavor physics are presented, using data from the ATLAS detector. The ϓ( nS ) and charmonium inclusive production cross sections are discussed. J/ψ production associated with a W vector boson is presented. An inclusive analysis of B + meson production is shown. Results on the production of heavy quarkonia are complemented by the measurement of inclusive φ meson production. The latest information on heavy flavor spectroscopy and searches for new physics using B -meson rare decays is also covered. These results are based on data samples collected during the 2011 and 2012 LHC running periods.
125401428
Measurement of the cross section of high transverse momentum $\it{Z\rightarrow b\bar{b}}$ production in proton--proton collisions at $\sqrt{s}=8 TeV$ with the ATLAS Detector
18086319
Study of a prototype detector for the Daya Bay neutrino experiment
The Daya Bay reactor neutrino experiment is designed to precisely measure the neutrino mixing angle y13. In order to study the details of the detector response and finalize the detector design, a prototype neutrino detector with a scale of 1/3 in diameter is constructed at the Institute of High Energy Physics (IHEP), Beijing. The detector is viewed by 45 8 00 photomultipliers, which are calibrated by LED light pulse. The energy response of the detector, including the resolution, linearity, spatial uniformity, etc., is studied by radioactive sources 133 Ba, 137 Cs, 60 Co, and 22 Na at various locations of the detector. The measurement shows that the detector, particularly the specially designed optical reflectors, works as expected. A Monte Carlo simulation based on the Geant4 package shows a good agreement with the experimental data.
119294887
Self-gravitational interaction in $z=$4 Horava-Lifshitz gravity
Motivated by recent works [1,2], the influences of self-gravitational interaction on the Hawking radiation are studied both for (3 + 1) and (4 + 1) dimensional black holes in $z = 4$ Ho\u{r}ava-Lifshitz gravity. It is found that the tunneling entropies $S_{B(3 + 1)}$ and $S_{B(4 + 1)}$ independent on particle's mass are consistent with the thermodynamical entropies $S_{BH(3 + 1)}$ and $S_{BH(4 + 1)}$, respectively. There is a very visible degree of uniformity between thermodynamics and quantum tunneling in $z = 4$ Ho\u{r}ava-Lifshitz gravity. It suggests that the entropies contained corrected terms could be explained well by the self-gravitational interaction of Hawking radiation. The study of tunneling process may shed light on understanding the Ho\u{r}ava-Lifshitz gravity.
118422695
Hadron Yield Correlation in Combination Models in High Energy AA Collisions
We study the hadron yield correlation in the combination models in high energy heavy ion collisions. We derive the relationship between the average yields of different hadrons produced in the combination of a system consisting of equal number of quarks and antiquarks. We present the results for the directly produced hadrons as well as those for the final hadrons including the strong and electromagnetic decay contributions. We also study the net quark influence by considering the case when the number of quarks is larger than that of the antiquarks. We make comparison with the data wherever possible.
119629879
Study of a prototype water Cherenkov detector for the Daya Bay neutrino experiment
The Daya Bay reactor neutrino experiment is designed to precisely measure the neutrino mixing angle theta(13). The anti-neutrino detectors are shielded by highly purified water against radioactivity and spallation neutrons from surrounding rocks. The water also serves as a Cherenkov detector to tag cosmic-ray muons, which induce main backgrounds. In order to study water purification and details of the detector response, a prototype water Cherenkov detector is constructed at the Institute of High Energy Physics (IHEP), Beijing. The detector is divided by Tyvek into two sections and viewed by two 8 in. photomultipliers. Cosmic-ray muons are used for detector response studies and a Monte Carlo simulation based on the Geant4 package shows good agreement with the experimental data. (C) 2012 Elsevier B.V. All rights reserved.
118525905
Yield correlations and $p_T$ dependence of charm hadrons in Pb + Pb collisions at $\sqrt{s_{NN}}= 2.76$ TeV
Recently the ALICE Collaboration has published a few data of charm hadrons in Pb + Pb collisions at the CERN Large Hadron Collider (LHC). We extend the quark combination to the charm sector and point out that the measurement of charm hadron yields can provide important insights into charm quark hadronization mechanism and properties of the hot and dense matter produced in high energy reactions. We propose several types of yield ratios, e.g. $D^{*+}/D^0$, $D_s^+/D^+$ and $\Lambda_c^+/D_s^+$, to measure various properties of low $p_T$ charm quark hadronization. We argue that ratios $D_s^+/D^0$ and $2D_s^+/(D^0+D^+)$ as the function of transverse momentum can serve as good probes for the dynamics of charm quark hadronization. We further make predictions for the yields and $p_T$ spectra of identified charm hadrons in central Pb + Pb collisions at $\sqrt{s_{NN}}= 2.76$ TeV.