Dynamic scale anomalous transport in QCD with electromagnetic background

TL;DR

This paper explores how electromagnetic fields induce a dynamic scale anomalous current in QCD, leading to observable effects like dilepton and diphoton production peaks in heavy ion collisions, through a dilaton effective theory.

Contribution

It introduces a novel mechanism where EM fields induce oscillatory dilaton fields causing scale anomalous currents in QCD, with phenomenological predictions for particle production.

Findings

Electromagnetic fields induce oscillatory dilaton fields in QCD.

Dynamic scale anomalous currents lead to characteristic peaks in dilepton and diphoton spectra.

Potential experimental signatures in heavy ion collision experiments.

Abstract

We discuss phenomenological implications of the anomalous transport induced by the scale anomaly in QCD coupled to an electromagnetic (EM) field, based on a dilaton effective theory. The scale anomalous current emerges in a way perfectly analogous to the conformal transport current induced in a curved spacetime background, or the Nernst current in Dirac and Weyl semimetals -- both current forms are equivalent by a "Weyl transformation". We focus on a spatially homogeneous system of QCD hadron phase, which is expected to be created after the QCD phase transition and thermalization. We find that the EM field can induce a dynamic oscillatory dilaton field which in turn induces the scale anomalous current. As the phenomenological applications, we evaluate the dilepton and diphoton productions induced from the dynamic scale anomalous current, and find that those productions include a characteristic peak structure related to the dynamic oscillatory dilaton, which could be tested in heavy ion collisions. We also briefly discuss the out-of-equilibrium particle production created by a nonadiabatic dilaton oscillation, which happens in a way of the so-called tachyonic preheating mechanism.