7 research outputs found
Multiplicity dependence of jet-like two-particle correlation structures in p-Pb collisions at 1asNN=5.02 TeV
Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p\u2013Pb collisions at a nucleon\u2013nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 < pT,assoc < pT,trig < 5.0 GeV/c is examined, to include correlations induced by jets originating from low momentum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |\u3b7| < 0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p\u2013Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton\u2013parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p\u2013Pb collisions. Further, the number scales only in the intermediate multiplicity region with the number of binary nucleon\u2013nucleon collisions estimated with a Glauber Monte-Carlo simulation
Latest results from CERES/NA45
In this talk latest results from the analysis of pairs emitted in Pb + Au collisions at 40 AGeV/c and a combined analysis of all data available at 158 AGeV/c are presented. The enhancement of low-mass pairs with respect to the expected yield from hadron decays first reported at 158 AGeV/c is also found at 40 AGeV/c and is even larger there. Comparing to various theoretical models based on annihilation, the data can only be reproduced, if the properties of the intermediate in the hot and dense medium are modified. Theoretically, the modification is linked to baryon density rather than temperature. Constraints from hadron data taken at the same beam energies indeed indicate a fireball evolution along a trajectory of higher baryon density at 40 AGeV/c, consistent with the observed larger enhancement factor
Production of charged pions, kaons and protons at large transverse momenta in pp and Pb–Pb collisions at s
Transverse momentum spectra of pi(+/-), K-+/- and p((p) over bar) up to p(T) = 20 GeV/c at mid-rapidity in pp, peripheral (60-80%) and central (0-5%) Pb-Pb collisions at v root s(NN) = 2.76 TeV have been measured using the ALICE detector at the Large Hadron Collider. The proton-to-pion and the kaon-to-pionratios both show a distinct peak at p(T) approximate to 3 GeV/c in central Pb-Pb collisions. Below the peak, p(T) 10 GeV/c particle ratios in pp and Pb-Pb collisions are in agreement and the nuclear modification factors for pi(+/-), K-+/- and p((p) over bar) indicate that, within the systematic and statistical uncertainties, the suppression is the same. This suggests that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets
Production of charged pions, kaons and protons at large transverse momenta in pp and Pb–Pb collisions at TeV
Transverse momentum spectra of pi(+/-), K-+/- and p((p) over bar) up to p(T) = 20 GeV/c at mid-rapidity in pp, peripheral (60-80%) and central (0-5%) Pb-Pb collisions at v root s(NN) = 2.76 TeV have been measured using the ALICE detector at the Large Hadron Collider. The proton-to-pion and the kaon-to-pionratios both show a distinct peak at p(T) approximate to 3 GeV/c in central Pb-Pb collisions. Below the peak, p(T) 10 GeV/c particle ratios in pp and Pb-Pb collisions are in agreement and the nuclear modification factors for pi(+/-), K-+/- and p((p) over bar) indicate that, within the systematic and statistical uncertainties, the suppression is the same. This suggests that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets
Multiplicity dependence of pion, kaon, proton and lambda production in p–Pb collisions at √sNN = 5.02 TeV
Inthis Letter, comprehensive results on π±,K±,K0S, p(pbar) and Λ(Λbar) production at mid-rapidity (0< yCMS < 0.5) in p–Pb collisions at √sNN = 5.02 TeV, measured by the ALICE detector at the LHC, are reported. The transverse momentum distributions exhibit a hardening as a function of event multiplicity, which is stronger for heavier particles. This behavior is similar to what has been observed in pp and Pb–Pb collisions at the LHC. The measured pT distributions are compared to d–Au, Au–Au and Pb–Pb results at lower energy and with predictions based on QCD-inspired and hydrodynamic models