Light-Front Holography in QCD and Hadronic Physics

TL;DR

This paper extends light-front holography in QCD to include light-quark masses, providing a framework that describes hadronic spectra, such as the K meson, while maintaining confinement criteria and Regge trajectories.

Contribution

It introduces a method to incorporate light-quark masses into the light-front holographic approach, preserving the confinement potential and spectral properties.

Findings

Successfully describes the K meson spectrum without changing the confinement scale

Maintains Wilson loop criteria for confinement with light quark masses

Establishes a semiclassical relativistic wave equation for arbitrary spin

Abstract

We describe a procedure to extend the light-front holographic approach to hadronic physics to include light-quark masses. The proposed framework allows us to extend the formalism of de Alfaro, Fubini and Furlan to the frame-independent light-front Hamiltonian theory in the approximation where the dynamics in the invariant transverse variable is unchanged to first order in the quark masses. The confinement potential follows from an effective theory which encodes the fundamental conformality of the classical QCD Lagrangian and leads to a semiclassical relativistic light-front wave equation for arbitrary spin. In particular, the K meson spectrum is successfully described without modifying the emerging confinement scale. The Wilson loop criteria for confinement is maintained, since for light quark masses a harmonic potential and linear Regge trajectories in the light-front form of dynamics corresponds to a linear potential in the usual instant-form.