Diffusive dynamics of critical fluctuations near the QCD critical point

Nahrgang, Marlene; Bluhm, Marcus; Schäfer, Thomas; Bass, Steffen A.

doi:10.1103/physrevd.99.116015

Title: Diffusive dynamics of critical fluctuations near the QCD critical point

Journal Article · 20 June 2019 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.99.116015 · OSTI ID:1609460

Nahrgang, Marlene ^[1]; Bluhm, Marcus ^[2]; Schäfer, Thomas ^[3]; Bass, Steffen A. ^[4]

Univ. de Nantes (France); GSI-Darmstadt (Germany). ExtreMe Matter Inst. (EMMI)
Univ. of Wroclaw (Poland)
North Carolina State Univ., Raleigh, NC (United States)
Duke Univ., Durham, NC (United States)

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. Herein 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.

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Research Organization:: North Carolina State University, Raleigh, NC (United States); Duke Univ., Durham, NC (United States)

Sponsoring Organization:: USDOE Office of Science (SC); European Union's Horizon 2020; National Science Centre of Poland (NCN); DoE Beam Energy Scan Theory (BEST) Topical Collaboration; ExtreMe Matter Institute (EMMI)

Grant/Contract Number:: FG02-03ER41260; FG02-05ER41367; 665778; UMO-2016/21/P/ST2/ 04035

OSTI ID:: 1609460

Alternate ID(s):: OSTI ID: 1546258

Journal Information:: Physical Review. D., Vol. 99, Issue 11; ISSN 2470-0010

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

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