Speaker
Christopher Plumberg
(The Ohio State University)
Description
One of the major lessons from the field of heavy-ion physics in the past several years has been the significance of the role played by event-by-event fluctuations in the evolution of a heavy-ion collision. Their important effects on many momentum-space observables (particle yields and spectra, anisotropic flows, etc.) have already been studied systematically, and some of the properties of their event-by-event distributions, and their consequences for the extraction of medium properties such as the specific viscosity of the quark-gluon plasma (QGP), are already known.
In this talk it is pointed out that similar event-by-event fluctuations of spatiotemporal observables provide complementary constraints on our understanding of the dynamical evolution of heavy-ion collisions. The relation of Hanbury Brown-Twiss (HBT) radii extracted from ensemble-averaged correlation function measurements to the mean of their event-by-event probability distribution is clarified, and a method to experimentally determine the mean and variance of this distribution is proposed and demonstrated using an ensemble of fluctuating events generated with the viscous hydrodynamic code VISH2+1. The sensitivity of the mean and variance of the HBT radii to the specific QGP shear viscosity $\eta/s$ is studied using simulations with the same code. We report sensitivity of the mean pion HBT radii and their variances to the temperature dependence of $\eta/s$ near the quark-hadron transition at a level similar (10-20%) to that which was previously observed for elliptic and quadrangular flow of charged hadrons.
References:
- Plumberg, C. and Heinz, U. "Interferometric signatures of the temperature dependence of the specific shear viscosity in heavy-ion collisions", Phys.Rev. C91 (2015) 5, 054905
- Plumberg, C. and Heinz, U. "Probing the properties of event-by-event distributions in Hanbury-Brown--Twiss radii", (forthcoming)
Author
Christopher Plumberg
(The Ohio State University)
Co-author
Ulrich Heinz
(The Ohio State University)
