Towards a Perfect QCD Gravity Dual

TL;DR

This paper explores tuning higher dimension operators in holographic QCD models with UV cutoffs to better match lattice glueball mass data, revealing a close IR-UV cutoff proximity and improved spectral predictions.

Contribution

It proposes a method to remove UV matter effects in holographic QCD by tuning operators at the cutoff, improving the match with lattice results.

Findings

IR and UV cutoffs are close in tuned models

Better match to lattice 0^{++} glueball masses

Improved geometry enhances 0^{-+} glueball predictions

Abstract

Many examples of gravitational duals exist of theories that are highly supersymmetric and conformal in the UV yet have the same massless states as {\cal N}=2,1,0 QCD. We discuss such theories with an explicit UV cutoff and propose that, by tuning higher dimension operators at the cutoff by hand, the effects of the extra matter states in the UV may be removed from the IR physics. We explicitly work in the AdS-Schwartzschild description of QCD_4 and tune the operator TrF^4 by relaxing the near horizon limit to reproduce the lattice 0^{++} glueball mass results. We find that to reproduce the lattice data, the IR and UV cutoffs lie close to each other and there is essentially no AdS-like period between them. The improved geometry gives a better match to the lattice data for 0^{-+} glueball masses.