Forces inside hadrons: pressure, surface tension, mechanical radius, and all that

TL;DR

This paper reviews the physics of energy-momentum tensor form factors in hadrons, focusing on their interpretation as mechanical properties like pressure and surface tension, and discusses experimental insights into the D-term.

Contribution

It provides a comprehensive review of the form factors of the energy-momentum tensor, including the D-term, and explores their physical interpretations and experimental status.

Findings

Insights into the mechanical properties of hadrons from form factors

Discussion of the D-term as a key global property

Summary of current experimental measurements

Abstract

The physics related to the form factors of the energy momentum tensor spans a wide spectrum of problems, and includes gravitational physics, hard exclusive reactions, hadronic decays of heavy quarkonia, and the physics of exotic hadrons described as hadroquarkonia. It also provides access to the "last global unknown property:" the D-term. We review the physics associated with the form factors of the energy-momentum tensor and the D-term, their interpretations in terms of mechanical properties, their applications, and the current experimental status.