Lattice simulations of adjoint QCD with one Dirac overlap fermion

TL;DR

This study uses lattice simulations with overlap fermions to analyze the infrared behavior of SU(2) adjoint QCD, finding evidence of confinement and chiral symmetry breaking without an infrared fixed point.

Contribution

It provides the first detailed lattice investigation of SU(2) adjoint QCD with overlap fermions, clarifying its infrared dynamics and symmetry breaking patterns.

Findings

No infrared fixed point detected

Evidence of confinement in the infrared regime

Chiral symmetry breaking confirmed

Abstract

In this work we investigate the infrared behaviour of a Yang-Mills theory coupled to a massless fermion in the adjoint representation of the gauge group SU(2). This model has many interesting properties, corresponding to the $\mathcal{N}=2$ Super-Yang-Mills theory without scalars and in the recent years there has been an increasing interest toward understanding whether confinement and fermion condensation occur at low energy. We simulate the theory on the lattice close to the massless limit using the overlap discretization of the fermion action, allowing a precise and clean study of the chiral symmetry breaking pattern and of the fermion condensate. We present results for the scale setting, the condensate and the running of the coupling constant through the gradient flow -- all of them pointing to a theory without an infrared fixed point and remaining confined deep in the infrared regime.