We study systematically the topological charge density and the chiral density correlations in the early stage of high energy nuclear collisions: the initial condition is given by the McLerran-Venugopalan model and the evolution of the gluon fields is studied via the Classical Yang-Mills equations up to proper time tau approximate to 1 fm/c for an SU(2) evolving Glasma. Topological charge is related to the gauge invariant E center dot B where E and B denote the color-electric and color-magnetic fields, while the chiral density is produced via the chiral anomaly of Quantum Chromodynamics. We study how the correlation lengths are related to the collision energy, and how the correlated domains grow up with proper time in the transverse plane for a boost invariant longitudinal expansion. We estimate the correlation lengths of both quantities, that after a short transient results of the order of the typical energy scale of the model, namely the inverse of the saturation scale. We estimate the proper time for the formation of a steady state in which the production of the chiral density in the transverse plane per unit rapidity slows down, as well as the amount of chiral density that would be present at the switch time between the Classical Yang-Mills evolution and the relativistic transport or hydro for the quark-gluon plasma phase.

Fluctuations of topological charge and chiral density in the early stage of high energy nuclear collisions

Hongfei Zhang;Marco Ruggieri
2020-01-01

Abstract

We study systematically the topological charge density and the chiral density correlations in the early stage of high energy nuclear collisions: the initial condition is given by the McLerran-Venugopalan model and the evolution of the gluon fields is studied via the Classical Yang-Mills equations up to proper time tau approximate to 1 fm/c for an SU(2) evolving Glasma. Topological charge is related to the gauge invariant E center dot B where E and B denote the color-electric and color-magnetic fields, while the chiral density is produced via the chiral anomaly of Quantum Chromodynamics. We study how the correlation lengths are related to the collision energy, and how the correlated domains grow up with proper time in the transverse plane for a boost invariant longitudinal expansion. We estimate the correlation lengths of both quantities, that after a short transient results of the order of the typical energy scale of the model, namely the inverse of the saturation scale. We estimate the proper time for the formation of a steady state in which the production of the chiral density in the transverse plane per unit rapidity slows down, as well as the amount of chiral density that would be present at the switch time between the Classical Yang-Mills evolution and the relativistic transport or hydro for the quark-gluon plasma phase.
2020
High Energy Physics - Phenomenology
High Energy Physics - Phenomenology
High Energy Physics - Theory
Nuclear Theory
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/549872
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