Speaker
Description
We study the shear viscosity induced cavitation in the Quark-Gluon Plasma (QGP) incorporating transverse expansion alongside chemical non-equilibrium dynamics. Chemical non-equilibrium is incorporated through parton fugacities, whose evolution is coupled to causal viscous relativistic hydrodynamics within the Gubser geometry. Using phenomenological temperature-dependent shear viscosity parameterisations, we study the evolution of the longitudinal pressure of the system and identify the conditions under which it becomes negative and thereby breaking down the hydrodynamic description. We demonstrate that shear induced cavitation scenario develops first at the centre of the fireball ($r=0$) during early times and subsequently extends towards larger radial distances, with transverse expansion accelerating its onset. We show that cavitation persists during chemical equilibration. Within our framework, we determine the critical initial shear viscosity $(\eta/s)_{\rm crit}$, below which cavitation does not occur throughout the evolution of QGP. Since hydrodynamics is found to successfully describe the phenomenology of heavy-ion collisions, our results provide a constraint on shear viscosity requiring the absence of cavitation during the QGP evolution. We find that the phenomenologically extracted $\eta/s$ from JETSCAPE analyses lie below the critical shear viscosity $(\eta/s)_{\rm crit}$ obtained in our framework.