Diffusive dynamics of critical fluctuations near the QCD critical point


Journal Article

© 2019 American Physical Society. A quantitatively reliable theoretical description of the dynamics of fluctuations in nonequilibrium is indispensable in the experimental search for the QCD critical point by means of ultrarelativistic heavy-ion collisions. In this paper we consider the fluctuations of the net-baryon density which becomes the slow, critical mode near the critical point. Due to net-baryon number conservation the dynamics is described by the fluid dynamical diffusion equation, which we extend to contain a white noise stochastic current. Including nonlinear couplings from the 3d Ising model universality class in the free energy functional, we solve the fully interacting theory in a finite size system. We observe that purely Gaussian white noise generates non-Gaussian fluctuations, but finite size effects and exact net-baryon number conservation lead to significant deviations from the expected behavior in equilibrated systems. In particular the skewness shows a qualitative deviation from infinite volume expectations. With this benchmark established we study the real-time dynamics of the fluctuations. We recover the expected dynamical scaling behavior and observe retardation effects and the impact of critical slowing down near the pseudocritical temperature.

Full Text

Duke Authors

Cited Authors

  • Nahrgang, M; Bluhm, M; Schäfer, T; Bass, SA

Published Date

  • June 20, 2019

Published In

Volume / Issue

  • 99 / 11

Electronic International Standard Serial Number (EISSN)

  • 2470-0029

International Standard Serial Number (ISSN)

  • 2470-0010

Digital Object Identifier (DOI)

  • 10.1103/PhysRevD.99.116015

Citation Source

  • Scopus