Schwinger model simulations with dynamical overlap fermions

TL;DR

This paper reports on simulations of the 2-flavour Schwinger model using dynamical overlap fermions, analyzing the microscopic Dirac spectrum and comparing results with chiral Random Matrix Theory predictions.

Contribution

It applies the overlap hypercube operator at light fermion masses to study topological sectors and compares eigenvalue averages with chiral RMT, providing new insights into the chiral condensate.

Findings

Eigenvalue densities in topological sectors 0 and 1 analyzed.

Chiral condensate values match analytical continuum predictions for light fermions.

Microscopic Dirac spectrum densities explored beyond previous RMT studies.

Abstract

We present simulation results for the 2-flavour Schwinger model with dynamical overlap fermions. In particular we apply the overlap hypercube operator at seven light fermion masses. In each case we collect sizable statistics in the topological sectors 0 and 1. Since the chiral condensate Sigma vanishes in the chiral limit, we observe densities for the microscopic Dirac spectrum, which have not been addressed yet by Random Matrix Theory (RMT). Nevertheless, by confronting the averages of the lowest eigenvalues in different topological sectors with chiral RMT in unitary ensemble we obtain -- for the very light fermion masses -- values for Sigma that follow closely the analytical predictions in the continuum.