Light-Front Holographic QCD from a Coherent State in String Theory

TL;DR

This paper demonstrates how Light-Front Holographic QCD can be embedded into string theory using a coherent state, reproducing hadron spectra and linear Regge trajectories at the QCD scale.

Contribution

It introduces a novel embedding of LFHQCD into string theory via a specific coherent state, linking hadron spectroscopy to string theory and gravity.

Findings

Reproduces linear Regge trajectories of hadrons

Mass scale of string states is reduced from Planck to QCD scale

Connects hadronic spectra to gravitationally dressed states in AdS3

Abstract

It is shown that Light-Front Holographic Quantum Chromodynamics (LFHQCD) can be embedded in type II string theory based on the coherent state $e^{-\frac{1}{\lambda} L_{-1}}|h\rangle$. Salient features of hadron spectroscopy as known from LFHQCD carry over to string theory, notably the linear Regge trajectories of mesons and baryons in the chiral limit where $\lambda$ defines the QCD scale. From the LFHQCD perspective, this is an avenue to implement hadron spin. From the string perspective, string theory remains as a TOE with excited states generally at the Planck scale. Yet due to the unique properties of the coherent state, the mass scale of the tower of massive states on it is broken down from the Planck scale to the QCD scale, thereby reproducing properties of hadronic spectra. Furthermore, connection exists to gravitationally dressed excited states in AdS3.