Reflections upon the Emergence of Hadronic Mass

TL;DR

This paper discusses the ongoing quest to understand the origin of most of the visible matter's mass, focusing on the role of Quantum Chromodynamics and recent experimental advances in probing hadronic structures.

Contribution

It highlights recent theoretical and experimental progress in elucidating the emergence of hadronic mass through QCD-related signals and advanced measurements of pion and kaon structures.

Findings

QCD provides clear signals for the emergence of hadronic mass.

Modern experiments are accessing observables related to EHM.

Understanding of pion and kaon parton distributions has advanced.

Abstract

With discovery of the Higgs boson, science has located the source for $\lesssim 2$% of the mass of visible matter. The focus of attention can now shift to the search for the origin of the remaining $\gtrsim 98$%. The instruments at work here must be capable of simultaneously generating the 1 GeV mass-scale associated with the nucleon and ensuring that this mass-scale is completely hidden in the chiral-limit pion. This hunt for an understanding of the emergence of hadronic mass (EHM) has actually been underway for many years. What is changing are the impacts of QCD-related theory, through the elucidation of clear signals for EHM in hadron observables, and the ability of modern and planned experimental facilities to access these observables. These developments are exemplified in a discussion of the evolving understanding of pion and kaon parton distributions.