The Effect of Higher Dimensional QCD Operators on the Spectroscopy of Bottom-Up Holographic Models

Sergey Afonin

doi:10.3390/universe7040102

Abstract

Within the bottom-up holographic approach to QCD, the highly excited hadrons are identified with the bulk normal modes in the fifth “holographic” dimension. We show that additional states in the same mass range can appear also from taking into consideration the 5D fields dual to higher dimensional QCD operators. The possible effects of these operators have not been taken into account in virtually any phenomenological applications. Using the scalar case as the simplest example, we demonstrate that the additional higher dimensional operators lead to a large degeneracy of highly excited states in the soft wall holographic model, and in the hard wall holographic model, they result in a proliferation of excited states. The considered model can be viewed as the first analytical toy model predicting a one-to-one mapping of the excited meson states to definite QCD operators, to which they prefer to couple.

Highlights

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The hard wall (HW) model turned out to be convenient to describe the physics of chiral symmetry breaking and pion formfactors [2], and the soft wall (SW) model is well accommodated for descriptions of linear Regge and radial trajectories, which were observed in light mesons [5,6,7,8]
Numerous extensions of SW model were proposed aimed at improving various aspects in the phenomenological descriptions of hadron spectroscopy and chiral symmetry breaking [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33]

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The Effect of Higher Dimensional QCD Operators on the Spectroscopy of Bottom-Up Holographic Models. The simplest and most important class of such functions is given by the two-point correlators J(x)J(y) , where J(x) represents a local QCD operator that interpolates the hadron states under consideration.

Results

Conclusion