Semi-inclusive lepto-production of hidden-charm exotic hadrons

TL;DR

This paper estimates the production rates of various hidden-charm exotic hadrons in lepton-proton scattering, suggesting they can be produced copiously at future electron-ion colliders, and compares predictions with existing experimental limits.

Contribution

It provides the first order-of-magnitude estimates for the semi-inclusive production cross sections of hidden-charm exotic states in lepton-proton collisions using simulation methods.

Findings

Predicted production rates are within experimental upper limits.

Exotic states can be copiously produced at future colliders.

Estimates support the molecular structure hypothesis for these hadrons.

Abstract

We investigate the semi-inclusive production of hidden-charm exotic states, including $X(3872)$, $Z_c$, $Z_{cs}$ and the pentaquark $P_c$ states, in lepton-proton scattering processes. These hadrons are close to the thresholds of a pair of charm and anticharm hadrons, and are assumed to have hadronic molecular structure as their main components. In order to give order-of-magnitude estimates of the cross sections, we use Pythia to simulate the short-distance productions of the constituent hadrons, which then rescatter to form the exotic hadrons. The estimates for the $X(3872)$ and $Z_c(3900)^\pm$ are not in conflict with the upper limits measured at the COMPASS experiment for the exclusive photoproduction process. The results here indicate that the considered hidden-charm states can be copiously produced at the proposed electron-ion colliders EicC and US-EIC.