Particle seismology: mechanical and gravitational properties from parton-hadron duality

TL;DR

This paper reviews how the internal mechanical and gravitational properties of hadrons can be understood through form factors, dispersion relations, and parton-hadron duality, aligning well with lattice QCD data.

Contribution

It provides a pedagogical overview connecting hadronic form factors, dispersion relations, and parton-hadron duality to describe hadron structure.

Findings

Successful description of lattice QCD data for pion and nucleon

Demonstrates the effectiveness of dispersion relations and meson dominance

Highlights the role of the stress-energy-momentum tensor in hadron structure

Abstract

The internal structure of hadrons is characterized by form factors which correspond to matrix elements of currents. Among those, the stress-energy-momentum tensor is a universally conserved quantity providing the gravitational form factors, from which mechanical properties may be derived via the response to the space-time fluctuations. They have received much attention because of their role as moments of the Generalized Parton Distributions, where the stress-energy-momentum tensor couples to two photons, and more recently, due to the explicit lattice QCD determination for the pion and nucleon. In these lectures we attempt a pedagogical review of the topic from a purely hadronic point of view, based on the notion of dispersion relations, meson dominance, and parton-hadron duality. We show that despite the overwhelming simplicity of the approach, a rather successful description of the lattice QCD data is achieved.