# EFT determination of the heavy-hybrid spin potential

## TL;DR

This paper derives the spin-dependent potential for heavy quarkonium hybrids using effective field theory, matching perturbative and nonperturbative parts, and applies it to predict hybrid spectra with lattice data validation.

## Contribution

It provides the first derivation of the spin-dependent potential for heavy-quark hybrids to order 1/m^2, including operators absent in standard quarkonia, and connects theory with lattice data.

## Key findings

- Derived spin-dependent potential for heavy hybrids at order 1/m^2.
- Fitted nonperturbative coefficients to lattice charmonium hybrid data.
- Predicted bottomonium hybrid spectrum using the new potential.

## Abstract

We study the spin splitting in the heavy quarkonium hybrid spectrum within the framework of an nonrelativistic effective field theory. We derive for the first time the spin-dependent part of the heavy-quark-antiquark potential for heavy quarkonium hybrids to order $1/m^2$ in the heavy-quark-mass expansion. We find that several operators that are not found in standard quarkonia appear, most remarkably an operator suppressed by only one power of the heavy-quark mass. By matching the weakly-coupled pNRQCD to the effective field theory in the regime of short heavy-quark-antiquark distances, we work out the matching coefficients of the spin-dependent operators, which are factorized into a perturbative and a nonperturbative part. The nonperturbative part can be expressed in terms of purely gluonic correlators. We fit the nonperturbative parts of the matching coefficients to lattice data of the charmonium hybrid spectrum and obtain results that respect the power counting. Using the obtained nonperturbative pieces, we compute the bottomonium hybrid spectrum with the spin-dependent potential, for which results from the lattice are still sparse.