Baryons and baryoniums in the perspective of QCD sum rules

TL;DR

This paper reviews the investigation of baryonium states, which are baryon-antibaryon systems, using QCD sum rules, highlighting recent experimental evidence and providing a detailed methodological overview.

Contribution

It offers a comprehensive review of baryonium studies with QCD sum rules, including calculation procedures and comparison with experimental data and other models.

Findings

Evidence for near-threshold $p\bar{p}$ bound states.

Benchmarking QCD sum rule predictions against experimental results.

Clarification of calculation procedures for baryonium analysis.

Abstract

Following the experimental confirmation of tetraquark and pentaquark states, the search for hexaquark states has emerged as a new frontier in hadron physics. Recent experimental progress, particularly by the BESIII collaboration, has provided compelling evidence for the existence of near-threshold $p\bar{p}$ bound states. These baryon-antibaryon systems, commonly referred to as baryoniums, are regarded as promising hexaquark candidates. In this article, we provide a comprehensive review of the investigations into baryonium states and their constituents, i.e., baryons, within the framework of QCD sum rules. We delineate the fundamental calculation procedures of this method to facilitate its practical application and benchmark the theoretical predictions against alternative models as well as the latest experimental data.