Low-lying meson spectrum of large $N_C$ strongly coupled lattice QCD

TL;DR

This paper calculates the low-lying meson mass spectrum in large $N_C$ lattice QCD using an improved strong-coupling expansion, showing good agreement with continuum results without arbitrary parameters.

Contribution

It introduces an improved strong-coupling expansion for large $N_C$ lattice QCD and evaluates meson masses, demonstrating consistency with continuum physics in the 't Hooft limit.

Findings

Good agreement with continuum meson masses at fourth order

Smooth 't Hooft limit without arbitrary parameters

Effective computation of low-lying meson spectrum

Abstract

We compute the low energy mass spectrum of lattice QCD in the large $N_C$ limit. Expanding around a gauge-invariant ground state, which spontaneously breaks the discrete chiral symmetry, we derive an improved strong-coupling expansion and evaluate, for any value of $N_C$, the masses of the low-lying states in the unflavored meson spectrum. We then take the 't Hooft limit by rescaling $g^2 N_C\to g^2$; the 't Hooft limit is smooth and no arbitrary parameters are needed. We find, already at the fourth order of the strong coupling perturbation theory, a very good agreement between the results of our lattice computation and the known continuum values.