Kinetic freeze-out temperature from yields of short-lived resonances
Anton Motornenko, Volodymyr Vovchenko, Carsten Greiner, Horst Stoecker
Abstract
A method to determine the kinetic freeze-out temperature in heavy-ion collisions from measured yields of short-lived resonances is presented. The resonance production is treated in the framework of a thermal model with an evolution between chemical and kinetic freeze-outs. The yields of many short-lived resonances are suppressed at $T={T}_{\mathrm{kin}}<{T}_{\mathrm{ch}}$. We determine the values of ${T}_{\mathrm{kin}}$ and ${T}_{\mathrm{ch}}$ for various centralities in Pb-Pb collisions at $\sqrt{{s}_{{}_{NN}}}=2.76$ TeV by fitting the abundances of both the stable hadrons and the short-lived resonances such as ${\ensuremath{\rho}}^{0}$ and ${\text{K}}^{*0}$, which were measured by the ALICE collaboration. This allows us to extract the kinetic freeze-out temperature from the measured hadron and resonance yields alone, independent of assumptions about the flow velocity profile and the freeze-out hypersurface. The extracted ${T}_{\mathrm{ch}}$ values exhibit a moderate multiplicity dependence whereas ${T}_{\mathrm{kin}}$ drops, from ${T}_{\mathrm{kin}}\ensuremath{\simeq}{T}_{\mathrm{ch}}\ensuremath{\simeq}155\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ in peripheral collisions to ${T}_{\mathrm{kin}}\ensuremath{\simeq}110\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ in 0%--20% central collisions. Predictions for other short-lived resonances are presented. A potential (non-)observation of a suppressed ${f}_{0}(980)$ meson yield will allow us to constrain the lifetime of that meson.