Production of pentaquarks in $pA$-collisions

TL;DR

This paper proposes that hidden-charm pentaquarks observed in weak decays can also be produced in proton-nucleus collisions, with sizable cross-sections, enabling new experimental studies of their structure and existence.

Contribution

It introduces a novel production mechanism for pentaquarks in proton-nucleus collisions and analyzes the expected cross-sections and experimental signatures.

Findings

Production cross-section is sizable across various internal structure scenarios.

Pentaquarks can be detected via invariant mass of forward $J/\psi$ and proton.

The process can test the existence of neutral pentaquark $P_c^0$.

Abstract

We argue that a hidden-charm pentaquark recently observed in weak decays of $\Lambda_{b}$ can be produced in proton-nucleus collisions without electroweak intermediaries. We analyze the production cross-section for several scenarios of internal structure and find that a cross-section is sizable. This process can be studied both in collider as well as in fixed-target experiments. In the former case, the pentaquarks are produced at very forward rapidities, whereas in the latter case, pentaquarks are produced with relatively small rapidities and can be easily detected via invariant mass distribution of a forward $J/\psi$ and a comoving proton. Additionally, the suggested process allows to check the existence of a neutral pentaquark $P_{c}^{0}$ (an isospin partner of $P_{c}^{+}$) predicted in several models. The rapidity and transverse momentum distributions of pentaquarks could provide comprehensive information about the $\bar{c}c$ component of this exotic baryon.