Speaker
Description
Relativistic viscous hydrodynamics has been widely used as an effective theory of the quark-gluon plasma (QGP) stage in high energy collisions. The analytical structure of hydrodynamics consists of a hydrodynamic and a non-hydrodynamic mode. The hydrodynamic mode is associated with an attractor solution and is considered to be the reason for the unreasonable effectiveness of hydrodynamics in explaining the soft sector observables. The non-hydrodynamic mode manifests as dissipative effects in the system. The shear relaxation time acts as a regulator of non-hydrodynamic mode. We exploit this feature to find the smallest size of QGP in peripheral proton-nucleus collisions using the state-of-the-art framework of JETSCAPE. As predicted by Paul Romatschke in Ref. [Eur. Phys. J. C (2017) 77:21], an abrupt increase in the second anisotropic flow coefficient in peripheral collisions for extreme values of shear relaxation time is a signature of breakdown of hydrodynamics. We find the threshold peripheral collisional centrality up to which we can safely employ hydrodynamics. We make a semi-quantitative estimate of the smallest volume and lifetime of QGP for the collision system of p+Pb at 5.02 TeV and p+Au at 200 GeV.
| Category | Theory |
|---|
