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

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.