Abstract
The yields of the K*(892)$^{0}$ and $\Phi$(1020) resonances are measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 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 < $p_{\rm T}$ < 5 GeV/$c$ for the K*(892)$^{0}$ and 0.5 < $p_{\rm T}$ < 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 rescattering 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 $p_{\rm T}$ distribution of the $\Phi$(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 $p_{\rm T}$, the p/$\Phi$(1020) ratio is flat in $p_{\rm T}$, 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 $p_{\rm T}$ 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 $\Xi$.
Highlights
Ultrarelativistic heavy-ion collisions are expected to produce a hot and dense state of matter, the quark-gluon plasma [1,2,3]
The main detector components used in this analysis are the V0 detector, the Inner Tracking System (ITS), and the Time Projection Chamber (TPC), which are located inside a 0.5 T solenoidal magnetic field
In order to extract the values of the mean transverse momentum pT and the pT-integrated particle yield dN/dy, these pT distributions are fitted with a Boltzmann-Gibbs blast-wave function [44], which assumes that the emitted particles are locally thermalized in a uniform-density source at a kinetic freeze-out temperature Tkin and move with a common collective transverse radial flow velocity field
Summary
Ultrarelativistic heavy-ion collisions are expected to produce a hot and dense state of matter, the quark-gluon plasma [1,2,3]. Combines thermal-model calculations with rescattering effects in the hadronic phase It predicts the ratios of (pT-integrated) resonance yields to the yields of stable particles as a function of both the chemical freeze-out temperature and the lifetime of the hadronic phase. While this model was derived for a(√RsNelNat=ivis1ti3c0. Since model calculations indicate that rescattering and regeneration modify the resonance signal more strongly for pT 2 GeV/c, signatures of chiral symmetry may be difficult to observe in the case of low-pT resonances which are reconstructed via hadronic decays. The focus here is on low and intermediate pT [0.3 < pT < 5 GeV/c for the K∗(892)0 and 0.5 < pT
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