History and Geography of Pentaquark Searches: Challenges and Pitfalls

TL;DR

This paper reviews the history, current searches, and challenges in detecting pentaquarks, highlighting recent discoveries of charm pentaquarks and debating the existence of light pentaquarks made of u, d, and s quarks.

Contribution

It provides a comprehensive overview of pentaquark research history, recent experimental results, and discusses unresolved questions about light pentaquark existence.

Findings

Recent LHCb discovery of charm pentaquarks.

Controversy over the existence of light pentaquarks.

Ongoing debate on the need for further dedicated searches.

Abstract

In this paper I review the history and geography of the pentaquark searches and discuss the current situation surrounding these searches performed at different facilities around the world. The possibility of the existence of multiquark states like tetraquarks and pentaquarks was already predicted by Gell-Mann based on the Constituent Quark Model (CQM), however more than half a century efforts in a wide range of experiments led to controversial situation, when the fate of the light quark pentaquarks is almost decided to not exist. The recent LHCb results on the observation of the charm pentaquarks in the invariant mass of $pJ/\psi $ from the $\Lambda_b\to K^- p J/\psi$ decay created a new wave of excitement and rises the question about the existence of the light pentaquarks. The main question which still remains to be clarified is whether already acquired evidences are sufficient to completely disregard the light pentaquarks and leave it out as an example of the scientific curiosity or there are still rooms for further, more dedicated efforts and scrupulous analyses to answer the question of the existence or non existence of the light pentaquarks made of $u, d$ and $s$ quarks.