21554167
Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton–proton collision data
This paper presents the performance of the ATLAS muon reconstruction during the LHC run with $$pp$$pp collisions at $$\sqrt{s}=7$$s=7–8 TeV in 2011–2012, focusing mainly on data collected in 2012. Measurements of the reconstruction efficiency and of the momentum scale and resolution, based on large reference samples of $${J/\psi \rightarrow \mu \mu }$$J/ψ→μμ, $$Z \rightarrow \mu \mu $$Z→μμ and $${\Upsilon \rightarrow \mu \mu }$$Υ→μμ decays, are presented and compared to Monte Carlo simulations. Corrections to the simulation, to be used in physics analysis, are provided. Over most of the covered phase space (muon $$|\eta |<2.7$$|η|<2.7 and $$5 \lesssim p_{\mathrm{T}}\lesssim 100$$5≲pT≲100 GeV) the efficiency is above $$99\,\%$$99% and is measured with per-mille precision. The momentum resolution ranges from $$1.7\,\%$$1.7% at central rapidity and for transverse momentum $$p_{\mathrm{T}}\simeq 10$$pT≃10 GeV, to $$4\,\%$$4% at large rapidity and $$p_{\mathrm{T}}\simeq 100$$pT≃100 GeV. The momentum scale is known with an uncertainty of $$0.05\,\%$$0.05% to $$0.2\,\%$$0.2% depending on rapidity. A method for the recovery of final state radiation from the muons is also presented.
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 ...
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.
201238536
Measurements of spin correlation in top-antitop quark events from proton-proton collisions at √s =7 TeV using the ATLAS detector
Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb(-1). Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.
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
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.
118644726
Hadron yield correlation and constituent quark degree of freedom in heavy ion collisions
Based on the assumption of the production of deconfined quark matter, we use a quark combination model to systematically investigate hadron yields in heavy ion collisions from RHIC $\sqrt{s_{NN}}=200, 130, 62.4$ GeV to SPS $E_{beam}=158, 80, 40, 30, 20 $ AGeV. We find that as the collision energy is greater than or equal to 30 AGeV the yields of various hadrons, their correlations, in particular, the observables $A=\frac{\bar{\Lambda} k^{-} p}{\Lambda k^{+} \bar{p}}$ and $B=\frac{\Lambda k^{-}\bar{\Xi}^{+}}{\bar{\Lambda} k^{+}\Xi^{-}}$, are all reproduced; however, as the collision energy drops to 20 AGeV quark combination fails. This indicates that the constituent quark degrees of freedom represent a decisive factor in thermal hadron production above 30 AGeV and seem to be invalid at 20 AGeV. In addition, hadron yields as well as particle ratios at midrapidity in the most central Pb+Pb collisions at $\sqrt{s_{NN}}=5.5$ TeV are predicted.
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.
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.
118750566
Baryon-antibaryon flavor correlation in quark-combination models in heavy-ion collisions
We extend the study of hadron yield correlation in combination models in a recent publication to baryon-anti-baryon flavor correlations in heavy ion collisions. We show that the universal behaviors of the anti-baryon to baryon yield ratios as functions of that of $K^-$ to $K^+$ are naturally explained. We study also the "mixed ratios" and propose other measurements that might be sensitive to the hadronization mechanism.