K∗(892)0 and ϕ(1020) production in Pb-Pb collisions at sNN√=2.76 TeV

Abstract

The yields of the K ∗ ( 892 ) 0 and ϕ ( 1020 ) resonances are measured in Pb-Pb collisions at √ sNN = 2.76 TeV through their hadronic decays using the ALICE detector. The measurements are performed in multiple centrality intervals at mid-rapidity ( | y | < 0.5 ) in the transverse-momentum ranges 0.3 < pT < 5 GeV/c for the K ∗ ( 892 ) 0 and 0.5 < pT < 5 GeV/c for the ϕ ( 1020 ). The yields of K ∗ ( 892 ) 0 are suppressed in central Pb-Pb collisions with respect to pp and peripheral Pb-Pb collisions (perhaps due to rescattering of its decay products in the hadronic medium), while the longer-lived ϕ ( 1020 ) meson is not suppressed. These particles are also used as probes to study the mechanisms of particle production. The shape of the pT distribution of the ϕ ( 1020 ) meson, but not its yield, is reproduced fairly well by hydrodynamic models for central Pb-Pb collisions. In central Pb-Pb collisions at low and intermediate pT, the p / ϕ ( 1020 ) ratio is flat in pT, while the p/π and ϕ ( 1020 ) / π ratios show a pronounced increase and have similar shapes to each other. These results indicate that the shapes of the pT distributions of these particles in central Pb-Pb collisions are determined predominantly by the particle masses and radial flow. Finally, ϕ ( 1020 ) production in Pb-Pb collisions is enhanced, with respect to the yield in pp collisions and the yield of charged pions, by an amount similar to the Λ and Ξ.