Enhanced heavy quark-pair production in strong SU(2) color field

TL;DR

This paper investigates non-perturbative heavy quark-pair production in strong, time-dependent SU(2) color fields during heavy ion collisions, revealing enhanced production at ultrarelativistic energies due to short pulse durations.

Contribution

It introduces a time-dependent chromo-electric field model with pulse-like evolution to study heavy quark production, showing enhancement over traditional suppression expectations.

Findings

Heavy quark-pair production is enhanced at ultrarelativistic energies.

Short pulse durations increase the efficiency of quark-pair production.

Flavour-dependent energy string tensions are proposed for model applications.

Abstract

Non-perturbative charm and bottom quark-pair production is investigated in the early stage of heavy ion collisions. Following our earlier works, the time-dependent study is based on a kinetic description of fermion-pair production in strong non-Abelian fields. We introduce time-dependent chromo-electric external field with a pulse-like time evolution, which simulates the overlap of two colliding heavy ions. The calculations is performed in a SU(2) color model with finite current quark masses. Yields of heavy quark-pairs are compared to the ones of light and strange quark-pairs. We show that the small inverse duration time of the field pulse determines the efficiency of the quark-pair production. Thus we do not see the expected suppression for heavy quark production, as follows from the Schwinger formula for constant field, but rather an enhanced heavy quark production at ultrarelativistic energies. We convert pulse duration time-dependent results into collisional energy dependence and introduce flavour-dependent energy string tensions, which can be used in string based model calculations at RHIC and LHC energies.