AdS/QCD models describing a finite number of excited mesons with Regge spectrum

TL;DR

This paper introduces a class of bottom-up holographic AdS/QCD models that describe a finite, realistic number of excited meson states with Regge-like spectra, incorporating anharmonic corrections to better match experimental observations.

Contribution

The authors develop holographic models with anharmonic potentials that accurately describe a finite number of light meson states, capturing nonlinear Regge trajectories and resonance merging effects.

Findings

Models produce linear and nonlinear Regge trajectories.

Spectrum includes a finite number of states proportional to N_c.

Accurately describes excited rho-meson spectrum.

Abstract

The typical AdS/QCD models deal with the large-N_c limit of QCD, as a consequence the meson spectrum consists of the infinite number of states that is far from the real situation. Basing on introduction of anharmonic corrections to the holographic potential, the corrections whose existence has been recently advocated, we construct a class of bottom-up holographic models describing arbitrary finite number of states in the sector of light mesons. Within the proposed approach, the spectrum of masses square has the following properties: It is linear, $m_n^2\sim n$, at not very large n, nonlinear at larger n, with the nonlinear corrections being subleading in 1/N_c, has a limiting mass, and the number of states is proportional to N_c. The considered holographic models reflect thereby the merging of resonances into continuum and the breaking of gluon string at sufficiently large quark-antiquark separation that causes the linear Regge trajectories to bend down. We show that these models provide a correct description for the spectrum of excited rho-mesons.