In this work a study of the fractional momentum loss ($S_{ \rm loss}$) as a function of the characteristic path-length ($L$) and the Bjorken energy density times the equilibration time ($\epsilon_{ \rm Bj}\tau_{ 0}$) for heavy-ion collisions at different $\sqrt{ s_{ \rm NN}}$ is presented. The study has been conducted using inclusive charged particles from intermediate to large transverse momentum ($5<p_{ \rm T}<20$ GeV/$c$). Within uncertainties and for all the transverse momentum values which were explored, the fractional momentum loss linearly increases with $({ \epsilon_{ \rm Bj}\tau_{ 0}})^{ 3/8}$$L$. The functional form of $S_{ \rm loss}$ vs. $({ \epsilon_{ \rm Bj}\tau_{ 0}})^{ 3/8}$$L$ seems to be universal. Moreover, for identified charged hadrons a linear relationship between $S_{ \rm loss}$ and $L$ is also observed. The behaviour of data could provide important information aimed to understand the parton energy loss mechanism in heavy-ion collisions and some insight into the expected effect for small systems.
Categories: hep-ph