Mesons and nucleons from holographic QCD in a unified approach

TL;DR

This paper develops a unified holographic QCD model to compute meson and nucleon masses and couplings, highlighting analytic solutions and IR scale challenges in the hard wall approach.

Contribution

It introduces a unified method for analyzing mesons and nucleons in holographic QCD with analytic solutions and discusses IR scale issues.

Findings

Derived approximate nucleon masses in small mass coupling region

Unified treatment of meson and nucleon properties with the same IR cutoff

Identified difficulties in avoiding IR scale problems in the hard wall model

Abstract

We investigate masses and coupling constants of mesons and nucleons within a hard wall model of holographic QCD in a unified approach. We first examine an appropriate form of fermionic solutions by restricting the mass coupling for the five dimensional bulk fermions and bosons. We then derive approximated analytic solutions for the nucleons and the corresponding masses in a small mass coupling region. In order to treat meson and nucleon properties on the same footing, we introduce the same infrared (IR) cut in such a way that the meson-nucleon coupling constants, i.e., g_{pi NN} and g_{rho NN} are uniquely determined. The first order approximation with respect to a dimensionless expansion parameter, which is valid in the small mass coupling region, explicitly shows difficulties to avoid the IR scale problem of the hard wall model. We discuss possible ways of circumventing these problems.