System size dependence of the K∗/K ratio at LHC energies

Abstract

In the beginning of high energy heavy ion collisions, a deconfined phase of quarks and gluons (QGP) is formed. After the QGP, there is a hadron gas (HG) phase, which evolves until the final fluid freeze-out. The study of hadron resonances, such as the K∗, may give valuable information about the HG phase. In a recent work, we studied the K∗ meson evolution in heavy ion collisions during the hadron gas phase. We used the production and absorption cross sections of the K∗ and K mesons in a hadron gas, which were calculated in a previous work. We computed the time evolution of the K∗ abundance and the K∗/K ratio during the hadron gas phase. Assuming a Bjorken type cooling and using an empirical relation between the freeze-out temperature and the central multiplicity density, we were able to write K∗/K as a function of (dN/dη(η = 0)). The obtained function is in very good agreement with recent experimental data. In this communication we review the main points of these works and expand the discussion.