Hadronic resonance production measured by ALICE at the LHC

Hadronic resonances constitute a valuable probe for the properties of the medium formed in heavy-ion collisions. In particular, they provide information on particle-formation mechanisms, the properties of the hadronic medium at freeze-out, and they contribute to the systematic study of energy loss and recombination. The study of resonance production in other collision systems such as pp and p-Pb forms a necessary baseline to disentangle initial-state effects from genuine medium-induced effects. The production of the K*(892)0 and ϕ(1020) resonances has been measured at mid-rapidity in different collision systems at LHC energies using the ALICE detector. Resonances are reconstructed via their hadronic decay in a wide momentum range, by exploiting the excellent particle-identification capabilities of the Time-Projection Chamber and the Time-Of-Flight system. First results on K*(892)0 and ϕ(1020) production in p-Pb collisions at √sNN=5.02 TeV at the LHC are presented. The resonance transverse momentum spectra and yields are measured as a function of the multiplicity of p-Pb collision. Ratios of resonance to long lived hadron production in Pb-Pb are compared with the same quantities measured in pp and p-Pb, in order to investigate rescattering effects. The ratio of ϕ to protons and pions as a function of pT suggests that in central Pb-Pb collisions it is the mass which drives the spectra shapes at low and intermediate pT, as in a hydrodynamically-evolving system. The nuclear modification factors (RAA, RpPb), recently measured up to high pT for resonances, are consistent with those of the stable hadrons.