Heavy quark diffusion in an overoccupied gluon plasma

Abstract

We extract the heavy-quark diffusion coefficient κ and the resulting momentum broadening 〈p2〉 in a far-from-equilibrium non-Abelian plasma. We find several features in the time dependence of the momentum broadening: a short initial rapid growth of 〈p2〉, followed by linear growth with time due to Langevin-type dynamics and damped oscillations around this growth at the plasmon frequency. We show that these novel oscillations are not easily explained using perturbative techniques but result from an excess of gluons at low momenta. These oscillation are therefore a gauge invariant confirmation of the infrared enhancement we had previously observed in gauge-fixed correlation functions. We argue that the kinetic theory description of such systems becomes less reliable in the presence of this IR enhancement.

Mass-suppressed effects in heavy quark diffusion

“…Conceivably, gradient flow [27] could offer further tools for studying the colour-magnetic correlator, along the lines discussed in ref. [28], and physical insight could be obtained from classical lattice gauge theory simulations [29,30]. Finally, it might be worth considering whether the colour-magnetic correlator captures some dispersive effects as well, in analogy with the colour-electric one [31].…”

QCD thermalization: Ab initio approaches and interdisciplinary connections

“…We discussed heavy quark pair production in the Glasma in Section IV. The diffusion coefficient of these heavy quarks was computed recently in this framework and scales as Q 3 S [604]. Heavy quark diffusion in Glasma-like environments and their subsequent evolution were also explored recently in several works [605][606][607].…”

Broad excitations in a 2+1D overoccupied gluon plasma

“…In practice, as discussed in refs. [40,45], we approximate this by a numerically more efficient transform where the lower limit t is…”

“…The (single-particle) distribution function is an important quantity that we can use to characterize the dynamical state of the system. We will use the same definitions as in our previous publications [36,40,45]…”

“…Moreover, it would be interesting to look at the heavy quark diffusion coefficient (as in ref. [45]), which is a gauge invariant observable sensitive to the same physical scales. We leave these studies to a further paper.…”