Impressions of the Meson Spectrum: Hybrids & Exotics, present and future

TL;DR

Recent advances in experimental and lattice QCD techniques are significantly enhancing our understanding of the complex and rich spectrum of hadrons, including hybrids and exotics, paving the way for future discoveries.

Contribution

This paper reviews recent progress in experimental and computational methods that are revealing the detailed structure of the hadron spectrum in QCD.

Findings

Experimental hints of hadron richness have increased.

Lattice QCD calculations are becoming more precise.

Upcoming experiments will likely uncover new hadronic states.

Abstract

It has long been expected that the spectrum of hadrons in QCD would be far richer and extensive than experiment has so far revealed. While there have been experimental hints of this richness for some time, it is really only in the last few years that dramatic progress has been seen in the exploration both experimentally and in calculations on the lattice. Precision studies enabled by new technology both with detectors and high performance computations are converging on an understanding of the spectrum in strong coupling QCD. These methodologies are laying the foundation for a decade of potential discovery that electro and photoproduction experiments at Jefferson Lab, which when combined with key results on $B$ and charmonium decays from both $e^+e^-$ and $pp$ colliders, should turn mere impressions of the light meson spectrum into a high definition picture.