Search results for "QUARK"
showing 10 items of 2905 documents
A Monte Carlo simulation for the elastic energy loss of high-energy partons in a strongly interacting medium
2012
Effective Field Theories for heavy probes in a hot QCD plasma and in the early universe
2017
There are many interesting problems in heavy-ion collisions and in cosmology that involve the interaction of a heavy particle with a medium. An example is the dissociation of heavy quarkonium seen in heavy-ion collisions. This was believed to be due to the screening of chromoelectric fields that prevents the heavy quarks from binding, however in the last years several perturbative and lattice computations have pointed out to the possibility that dissociation is due to the finite lifetime of a quarkonium state inside the medium. Regarding cosmology, the study of the behavior of heavy Majorana neutrinos in a hot medium is important to understand if this model can explain the origin of dark ma…
Inclusive quarkonium production at forward rapidity in pp collisions at √s = 8 TeV
2016
We report on the inclusive production cross sections of J/ψ, ψ(2S), ϒ(1S), ϒ(2S) and ϒ(3S), measured at forward rapidity with the ALICE detector in pp collisions at a center-of-mass energy √s = 8 TeV. The analysis is based on data collected at the LHC and corresponds to an integrated luminosity of 1.23 pb−1. Quarkonia are reconstructed in the dimuon-decay channel. The differential production cross sections are measured as a function of the transverse momentum pT and rapidity y, over the pT ranges 0 < pT < 20 GeV/c for J/ψ, 0 < pT < 12 GeV/c for all other resonances, and for 2.5 < y < 4. The cross sections, integrated over pT and y, and assuming unpolarized quarkonia, are σJ/ψ = 8.98 ± 0.04 …
First observation and study of the K± → π±π0e+e− decay
2018
The NA48/2 experiment at CERN reports the first observation of the K-+/- -> pi(+/-)pi(0)e(+)e(-) decay from an exposure of 1.7 x 10(11) charged kaon decays recorded in 2003-2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region, BR(K-+/- -> pi(+/-)pi(0)e(+)e(-)) = (4.24 +/- 0.14) x 10(-6). The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated.
Heavy quarkonium suppression in a fireball
2018
Measurement of the top quark charge in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
2013
A measurement of the top quark electric charge is carried out in the ATLAS experiment at the Large Hadron Collider using 2.05 fb[superscript −1] of data at a centre-of-mass energy of 7 TeV. In units of the elementary electric charge, the top quark charge is determined to be 0.64 ± 0.02 (stat.) ± 0.08 (syst.) from the charges of the top quark decay products in single lepton t[¯ over t] candidate events. This excludes models that propose a heavy quark of electric charge −4/3, instead of the Standard Model top quark, with a significance of more than 8σ.
"Table 3" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV wi…
2020
Acceptance times selection efficiency for Kaluza-Klein gluon Γ=30% as a function of top-quark pair mass for all regions A–D in the resolved analysis and the combination of all SRs in the boosted analysis.
"Table 20" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Expected and observed upper limits on the cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a function of the gluon mass.
"Table 16" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Expected and observed upper limits on the cross-section times branching fraction of topcolor-assisted-technicolor Z$^{\prime}_{TC2}$ decaying into top-quark pair as a function of the Z$^{\prime}_{TC2}$ mass.
"Table 17" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Expected and observed upper limits on the cross-section times branching fraction of A1 axial-vector mediator decaying into top-quark pair as a function of the mediator mass.