Connecting real-time properties of the massless Schwinger model to the massive case

TL;DR

This study uses classical-statistical lattice simulations to connect the real-time dynamics of the massless Schwinger model to the massive case, revealing that massless properties emerge at large gauge coupling to mass ratio.

Contribution

It demonstrates that the massless limit effectively describes the dynamics of the massive Schwinger model across a range of masses using lattice simulations.

Findings

Massless properties emerge at large g/m ratios.

Massless limit accurately describes dynamics for various masses.

External charge scenarios closely match self-consistent simulations.

Abstract

Quantum electrodynamics in $1 + 1$ space-time dimensions is analytically solvable for massless fermions, while no solution is known for massive fermions. Employing the classical-statistical approach, we simulate the real-time dynamics on a lattice using Wilson fermions with mass $m$ at gauge coupling $g$. It is shown that quantitative properties of the massless Schwinger model are emerging in the limit of large $g/m$. We investigate two scenarios corresponding to opposite charges which are either held fixed or moving back-to-back along the light cone, as employed in effective descriptions for jet energy loss and photon production in the context of heavy-ion collisions. Remarkably, we find that the dynamics is rather well described by the massless limit for a wide range of mass values at fixed coupling. Moreover, our study shows that previous approximate scenarios with external charges on the light cone rather accurately capture the self-consistent dynamics of the energy conserving simulation.