Thermal dilepton production within conformal viscous Gubser flow

Abstract: By employing the Gubser solutions of causal relativistic second-order Israel-Stewart hydrodynamics, we study the thermal dilepton production from heavy-ion collisions, considering the transverse expansion of the viscous hot QCD medium along with longitudinal boost-invariance. We analyze the evolution of the temperature and shear stress profiles of the QCD matter under Gubser flow for different values of the associated parameter $q$ (inverse length scale). We study the dilepton production using leading order Born rates from QGP and hadronic sectors under Gubser geometry. Viscous modified dilepton rate is calculated using the first-order Chapman-Enskog (CE) like non-equilibrium correction of the particle distribution function. Our study indicates that lower values of $q$ result in the enhancement of the emitted dilepton spectra. We also determine the effective temperature of the hot QCD medium from the inverse slope of transverse mass spectra, for different $q$. We find that the effective temperature determined from the dilepton spectra for a smaller system to be higher. Further, we compare the strength of CE like and Grad's viscous correction to the ideal dilepton spectra and find that CE type viscous corrections are well behaved compared to that of Grad's in the presence of transverse flow.