Spectrum of orientifold QCD in the strong coupling and hopping expansion approximation

TL;DR

This paper uses strong coupling and hopping expansion methods to calculate meson masses in lattice Yang-Mills theories with various fermion representations, providing insights into phase transitions and consistency with theoretical equivalences.

Contribution

It introduces a novel application of strong coupling and hopping expansions to compute meson spectra in orientifold QCD, including corrections and phase transition analysis.

Findings

Results align with orientifold planar equivalence.

Identifies a bulk phase transition at beta~2.

Provides estimates for critical bare mass.

Abstract

We use the strong coupling and hopping parameter expansions to calculate the pion and rho meson masses for lattice Yang-Mills gauge theories with fermions in irreducible two-index representations, namely the adjoint, symmetric and antisymmetric. The results are found to be consistent with orientifold planar equivalence, and leading order 1/N corrections are calculated in the lattice phase. An estimate of the critical bare mass, for which the pion is massless, is obtained as a function of the bare coupling. A comparison to data from the two-flavour SU(2) theory with adjoint fermions gives evidence for a bulk phase transition at beta~2, separating a pure lattice phase from a phase smoothly connected to the continuum.