Search results for "PB COLLISIONS"

Exclusive J=ψ Photoproduction off Protons in Ultraperipheral p-Pb Collisions at √sNN = 5.02 TeV

2014

Azimuthal correlations of prompt D mesons with charged particles in pp and p–Pb collisions at √sNN = 5.02 TeV

2020

The measurement of the azimuthal-correlation function of prompt D mesons with charged particles in pp collisions at √s = 5.02 TeV and p–Pb collisions at √sNN = 5.02 TeV with the ALICE detector at the LHC is reported. The D0D0, D+D+, and D∗+D∗+ mesons, together with their charge conjugates, were reconstructed at midrapidity in the transverse momentum interval 30.3 GeV/c and pseudorapidity |η|<0.8. The properties of the correlation peaks appearing in the near- and away-side regions (for Δφ≈0 and Δφ≈π, respectively) were extracted via a fit to the azimuthal correlation functions. The shape of the correlation functions and the near- and away-side peak features are found to be consistent in pp a…

Measurement of an Excess in the Yield of J/ψ at Very Low pT in Pb-Pb Collisions at √sNN = 2.76 TeV

2016

We report on the first measurement of an excess in the yield of J=ψ at very low transverse momentum (pT < 0.3 GeV=c) in peripheral hadronic Pb-Pb collisions at √sNN=2.76  TeV, performed by ALICE at the CERN LHC. Remarkably, the measured nuclear modification factor of J=ψ in the rapidity range 2.5 <y< 4 reaches about 7 (2) in the pT range 0–0.3 GeV=c in the 70%–90% (50%–70%) centrality class. The J=ψ production cross section associated with the observed excess is obtained under the hypothesis that coherent photoproduction of J=ψ is the underlying physics mechanism. If confirmed, the observation of J=ψ coherent photoproduction in Pb-Pb collisions at impact parameters smaller than twice the nu…

Centrality Dependence of the Charged-Particle Multiplicity Density at Midrapidity in Pb-Pb Collisions at √sNN = 5.02 TeV

2016

The pseudorapidity density of charged particles, dNch=dη, at midrapidity in Pb-Pb collisions has been measured at a center-of-mass energy per nucleon pair of √sNN=5.02 TeV. For the 5% most central collisions, we measure a value of 1943±54. The rise in dNch=dη as a function of √sNN is steeper than that observed in proton-proton collisions and follows the trend established by measurements at lower energy. The increase of dNch=dη as a function of the average number of participant nucleons, hNparti, calculated in a Glauber model, is compared with the previous measurement at √sNN=2.76 TeV. A constant factor of about 1.2 describes the increase in dNch=dη from √sNN=2,76 to 5.02 TeV for all central…

Centrality dependence of the nuclear modification factor of charged pions, kaons, and protons in Pb-Pb collisions at √sNN = 2.76 TeV

2016

Transverse momentum (pT) spectra of pions, kaons, and protons up to pT = 20 GeV/c have been measured in Pb-Pb collisions at √sNN = 2.76 TeV using the ALICE detector for six different centrality classes covering 0%–80%. The proton-to-pion and the kaon-to-pion ratios both show a distinct peak at pT ≈ 3 GeV/c in central Pb-Pb collisions that decreases for more peripheral collisions. For pT > 10 GeV/c, the nuclear modification factor is found to be the same for all three particle species in each centrality interval within systematic uncertainties of 10%–20%. This suggests there is no direct interplay between the energy loss in the medium and the particle species composition in the hard core of …

One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at √sNN = 2.76 TeV

2015

The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of π±π±, K±K±, K0 SK0 S, pp, and pp correlations from Pb-Pb collisions at √sNN = 2.76 TeV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. The comparison of the measured radii with the predictions from a hydrokinetic model is discussed. The pion and kao…

Production of inclusive Υ(1S) and Υ(2S) in p–Pb collisions at √sNN=5.02TeV

2015

Measurement of transverse energy at midrapidity in Pb-Pb collisions at √sNN = 2.76 TeV

2016

We report the transverse energy (ET) measured with ALICE at midrapidity in Pb-Pb collisions at √sNN = 2.76 TeV as a function of centrality. The transverse energy was measured using identified single-particle tracks. The measurement was cross checked using the electromagnetic calorimeters and the transverse momentum distributions of identified particles previously reported by ALICE. The results are compared to theoretical models as well as to results from other experiments. The mean ET per unit pseudorapidity (η), dET/dη , in 0%–5% central collisions is 1737 ± 6(stat.) ± 97(sys.) GeV. We find a similar centrality dependence of the shape of dET/dη as a function of the number of participating …

Forward-central two-particle correlations in p–Pb collisions at √sNN = 5.02 TeV

2016

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2 GeV/c. peerReviewed