Insights into the exotic charged states $Z_b(10610)$ and $Z_b(10650)$ from their photoproduction off nuclei

TL;DR

This paper investigates the photoproduction of charged bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$ off nuclei, exploring their internal structures through various scenarios and predicting observable differences for future experimental verification.

Contribution

It introduces a collision model to analyze the photoproduction of $Z_b$ states, considering multiple internal configuration scenarios and predicting measurable differences to determine their structure.

Findings

Distinct sensitivity of observables to $Z_b$ internal structures.

Predicted differences in excitation functions and cross sections.

Potential for experimental determination of $Z_b$ configurations.

Abstract

The possibility to study the nature of the famous charged bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$, which is by far the best known, from their inclusive photoproduction off nuclei near the kinematic threshold is investigated within the collision model based on the nuclear spectral function. The model accounts for $Z_b(10610)^{\pm}$ and $Z_b(10650)^{\pm}$ production in direct photon--nucleon interactions as well as four different scenarios for their intrinsic configurations: compact tetraquarks, molecules of the two open-beauty mesons and two mixtures of both of them for each of $Z_b$ state. We calculate within these scenarios the absolute and relative excitation functions on $^{12}$C and $^{184}$W nuclei at photon energies of 61--90 GeV, the absolute momentum differential cross sections and ratios of them for their production off these target nuclei at laboratory polar angles of 0$^{\circ}$--5$^{\circ}$ and for photon energy of 75 GeV as well as the A-dependences of the transparency ratios for the $Z_b(10610)^{\pm}$ mesons at photon energy of 75 GeV. We show that the absolute and relative observables considered reveal distinct sensitivity to the $Z_b(10610)^{\pm}$ and $Z_b(10650)^{\pm}$ internal structures. Therefore, they might be useful for the determination of these structures from the comparison of them with the experimental data from the future high-precision experiments at the upcoming experimental facilities, such as the planned high-luminosity electron-ion colliders in the United States and China.