A note on the glueball mass spectrum

TL;DR

This paper analytically computes glueball mass spectra using supergravity duality, providing precise eigenvalues that test the conjectured gauge/gravity correspondence and improve upon previous numerical methods.

Contribution

It introduces an analytical method for calculating glueball eigenvalues in supergravity duals, refining prior numerical approaches and enabling high-precision tests of the duality.

Findings

Eigenvalues for QCD3 and QCD4 glueballs computed with high precision.

Corrections to the WKB approximation for eigenvalues identified.

Results closely match previous numerical computations.

Abstract

A conjectured duality between supergravity and $N=\infty$ gauge theories gives predictions for the glueball masses as eigenvalues for a supergravity wave equations in a black hole geometry, and describes a physics, most relevant to a high-temeperature expansion of a lattice QCD. We present an analytical solution for eigenvalues and eigenfunctions, with eigenvalues given by zeroes of a certain well-computable function $r(p)$, which signify that the two solutions with desired behaviour at two singular points become linearly dependent. Our computation shows corrections to the WKB formula $m^2= 6n(n+1)$ for eigenvalues corresponding to glueball masses QCD-3, and gives the first states with masses $m^2=$ 11.58766; 34.52698; 68.974962; 114.91044; 172.33171; 241.236607; 321.626549, ... . In $QCD_4$, our computation gives squares of masses 37.169908; 81.354363; 138.473573; 208.859215; 292.583628; 389.671368; 500.132850; 623.97315 ... for $O++$. In both cases, we have a powerful method which allows to compute eigenvalues with an arbitrary precision, if needed so, which may provide quantative tests for the duality conjecture. Our results matches with the numerical computation of [5] well withing precision reported there in both $QCD_3$ and $QCD_4$ cases. As an additional curiosity, we report that for eigenvalues of about 7000, the power series, although convergent, has coefficients of orders ${10}^{34}$; tricks we used to get reliably the function $r(p)$, as also the final answer gets small, of order ${10}^{-6}$ in $QCD_4$. In principle we can go to infinitely high eigenavalues, but such computations maybe impractical due to corrections.