Dynamical initial state model for relativistic heavy-ion collisions

TL;DR

This paper introduces a comprehensive 3D initial state model for relativistic heavy-ion collisions that accounts for dynamical nucleon deceleration and energy deposition, enabling detailed studies of initial conditions and their impact on collision observables.

Contribution

The model uniquely incorporates dynamical deceleration of participants and energy deposition along strings, with implementation into 3+1D hydrodynamics for realistic simulation of heavy-ion collisions.

Findings

Net-baryon rapidity distributions modeled

Rapidity correlations analyzed

Geometry rapidity decorrelation studied

Abstract

We present a fully three-dimensional model providing initial conditions for energy and net-baryon density distributions in heavy ion collisions at arbitrary collision energy. The model includes the dynamical deceleration of participating nucleons or valence quarks, depending on the implementation. The duration of the deceleration continues until the string spanned between colliding participants is assumed to thermalize, which is either after a fixed proper time, or a fluctuating time depending on sampled final rapidities. Energy is deposited in space-time along the string, which in general will span a range of space-time rapidities and proper times. We study various observables obtained directly from the initial state model, including net-baryon rapidity distributions, 2-particle rapidity correlations, as well as the rapidity decorrelation of the transverse geometry. Their dependence on the model implementation and parameter values is investigated. We also present the implementation of the model with 3+1 dimensional hydrodynamics, which involves the addition of source terms that deposit energy and net-baryon densities produced by the initial state model at proper times greater than the initial time for the hydrodynamic simulation.