Evidence of rescattering effect in Pb-Pb collisions at the LHC through production of K*(892)(0) and phi(1020) mesons

Abstract

Measurements of K*(892)(0) and phi(1020) resonance production in Pb-Pb and pp collisions at root s(NN) = 5.02 TeV with the ALICE detector at the Large Hadron Collider are reported. The resonances are measured at midrapidity (vertical bar y vertical bar <0.5) via their hadronic decay channels and the transverse momentum (p(T)) distributions are obtained for various collision centrality classes up to p(T) = 20 GeV/c. The p(T)-integrated yield ratio K*(892)(0)/K in Pb-Pb collisions shows significant suppression relative to pp collisions and decreases towards more central collisions. In contrast, the phi(1020)/K ratio does not show any suppression. Furthermore, the measured K*(892)(0)/K ratio in central Pb-Pb collisions is significantly suppressed with respect to the expectations based on a thermal model calculation, while the phi(1020)/K ratio agrees with the model prediction. These measurements are an experimental demonstration of rescattering of K*(892)(0) decay products in the hadronic phase of the collisions. The K*(892)(0)/K yield ratios in Pb-Pb and pp collisions are used to estimate the time duration between chemical and kinetic freeze-out, which is found to be similar to 4-7 fm/c for central collisions. The p(T)-differential ratios of K*(892)(0)/K, phi(1020)/K, K*(892)(0)/pi, phi(1020)/pi, p/K*(892)(0) and p/phi(1020) are also presented for Pb-Pb and pp collisions at root s(NN) = 5.02 TeV. These ratios show that the rescattering effect is predominantly a low-p(T) phenomenon. (C) 2020 The Author(s). Published by Elsevier B.V.