K*(892)0 and phi(1020) production in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV

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2.76 TeV
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The yields of the K*(892)0 and phi(1020) resonances are measured in Pb-Pb collisions at 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 phi(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 re-scattering of its decay products in the hadronic medium), while the longer lived phi(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 phi(1020) meson, but not its yield, is reproduced fairly well by hydrodynamical models for central Pb-Pb collisions.  In central Pb-Pb collisions at low and intermediate pT, the p/phi(1020) ratio is flat in pT, while the p/pi and phi(1020)/pi 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, phi(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 Lambda and Xi.