Light-heavy-ion collisions: a window into pre-equilibrium QCD dynamics?

P. Romatschke

doi:10.1140/epjc/s10052-015-3509-3

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2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2015) 75: 305
https://doi.org/10.1140/epjc/s10052-015-3509-3

Regular Article - Theoretical Physics

Light-heavy-ion collisions: a window into pre-equilibrium QCD dynamics?

P. Romatschke^*

University of Colorado, Boulder, USA

^* e-mail: paul.romatschke@colorado.edu

Received: 12 March 2015
Accepted: 8 June 2015
Published online: 3 July 2015

Abstract

Relativistic collisions of light on heavy ions (p + Au at $\sqrt{s}=7.7$ GeV, p + Au , d + Au , $$^3$$ He + Au at $\sqrt{s}=62.4$ GeV and 200 GeV and p + Pb , $$^3$$ He + Pb at $\sqrt{s}=5.02$ TeV) are simulated using “superSONIC”, a model that includes pre-equilibrium flow, viscous hydrodynamics and a hadronic cascade afterburner. Even though these systems have strong gradients and only consist of at most a few tens of charged particles per unit rapidity, one finds evidence that a hydrodynamic description applies to these systems. Based on these simulations, the presence of a triangular flow component in d + Au collisions at $\sqrt{s}=200$ GeV is predicted to be similar in magnitude to that found in $$^3$$ He + Au collisions. Furthermore, the $$v_3(p_T)$$ ratio of $$^3$$ He + Au to d + Au is found to be sensitive to the presence of pre-equilibrium flow. This would imply an experimentally accessible window into pre-equilibrium QCD dynamics using light-heavy-ion collisions.