# On the hadron mass decomposition

## TL;DR

This paper introduces a new hadron mass decomposition that incorporates pressure effects and discusses the implications of Lorentz covariance and stability constraints, challenging traditional decompositions.

## Contribution

It proposes a novel mass decomposition method accounting for pressure effects and clarifies the limitations of traditional quark and gluon contributions.

## Key findings

- Quark and gluon forces inside nucleons are balanced.
- Pressure effects are crucial for accurate mass decomposition.
- Traditional decompositions overlook pressure contributions.

## Abstract

We argue that the standard decompositions of the hadron mass overlook pressure effects, and hence should be interpreted with great care. Based on the semiclassical picture, we propose a new decomposition that properly accounts for these pressure effects. Because of Lorentz covariance, we stress that the hadron mass decomposition automatically comes along with a stability constraint, which we discuss for the first time. We show also that if a hadron is seen as made of quarks and gluons, one cannot decompose its mass into more than two contributions without running into trouble with the consistency of the physical interpretation. In particular, the so-called quark mass and trace anomaly contributions appear to be purely conventional. Based on the current phenomenological values, we find that in average quarks exert a repulsive force inside nucleons, balanced exactly by the gluon attractive force.