Exploring the Spectrum of Heavy Quarkonium Hybrids with QCD Sum Rules

TL;DR

This study uses updated QCD sum rules including dimension-six condensates to predict heavy quarkonium hybrid masses, confirming supermultiplet structures and challenging the pure charmonium hybrid interpretation of X(3872).

Contribution

Incorporates dimension-six condensates into QCD sum rules for more reliable heavy quarkonium hybrid mass predictions.

Findings

Negative-parity states form the lightest hybrid supermultiplet.

Positive-parity states belong to a heavier supermultiplet.

Results disfavor X(3872) as a pure charmonium hybrid.

Abstract

QCD Laplace sum rules are used to calculate heavy quarkonium (charmonium and bottomonium) hybrid masses in several distinct $J^{PC}$ channels. Previous studies of heavy quarkonium hybrids did not include the effects of dimension-six condensates, leading to unstable sum rules and unreliable mass predictions in some channels. We have updated these sum rules to include dimension-six condensates, providing new mass predictions for the spectra of heavy quarkonium hybrids. We confirm the finding of other approaches that the negative-parity $J^{PC}=(0,1,2)^{-+},\,1^{--}$ states form the lightest hybrid supermultiplet and the positive-parity $J^{PC}=(0,1)^{+-},\,(0,1,2)^{++}$ states are members of a heavier supermultiplet. Our results disfavor a pure charmonium hybrid interpretation of the $X(3872)$, in agreement with previous work.