Lattice-QCD validation of hadron mass and trace-anomaly decomposition sum rules

TL;DR

This paper validates hadron mass and trace-anomaly sum rules using lattice-QCD, providing first-principles calculations of their components, including gluonic contributions and gravitational form factors, for charmonia states.

Contribution

It introduces a nonperturbative lattice-QCD framework for verifying multiple hadron mass decomposition sum rules within a unified renormalization scheme.

Findings

Gluonic contributions to charmonia masses are about 15%.

Trace-anomaly contribution in the Ji sum rule is approximately 6%.

Gluonic component of the trace anomaly in the Hatta-Rajan-Tanaka sum rule is around 35%.

Abstract

We present the first lattice-QCD validation of multiple sum rules associated with quark-gluon decomposition of hadron mass by computing all components from first principles. We achieve this through nonperturbative renormalization of the QCD energy-momentum tensor, including its trace, in a gradient-flow scheme, followed by continuum extrapolations, two-loop matching to the $\overline{\mathrm{MS}}$ scheme, and zero-flow-time extrapolations. These ingredients enable a direct and simultaneous verification, in a common renormalization scheme and scale, of multiple energy-density-based and trace-based mass decomposition sum rules proposed in the literature. We demonstrate the framework for the $\eta_c$ and $J/\psi$ charmonia using three fine lattice spacings with a physical strange-quark and near-physical up- and down-quark masses. We present the first lattice-QCD results for the gravitational form factor $\bar{C}$. We find sizable gluonic contributions to charmonia masses at the hadronic scale, $\sim 15\%$ in the Lorc\'e and Metz-Pasquini-Rodini decompositions. The trace-anomaly contribution in the Ji sum rule is $\sim 6\%$, while the gluonic component of the trace anomaly in the Hatta-Rajan-Tanaka sum rule is $\sim 35\%$. The method is general and can be straightforwardly adopted for lattice-QCD calculations of mass and spin decompositions as well as gravitational form factors of other hadrons and nuclei.