$\gamma, J/\psi$ production through ISR process in electron-positron annihilation at B-factories

TL;DR

This paper investigates the production of $J/\psi$ and $\Upsilon(1S)$ via initial state radiation in electron-positron collisions at B-factories, calculating cross sections and decay rates using the Bethe-Salpeter framework and comparing with experimental data.

Contribution

It introduces a Bethe-Salpeter equation-based calculation of ISR-induced quarkonium production and decay, extending analysis to both $J/\psi$ and $\Upsilon(1S)$ states.

Findings

Calculated cross sections agree with BaBar data.

Provided detailed decay branching ratios for $J/\psi$ and $\Upsilon(1S)$.

Extended the analysis framework to bottomonium states.

Abstract

We study the Initial state radiation (ISR) process, $e^- e^+ \rightarrow^*\gamma\rightarrow \gamma +J/\psi$ observed at high luminosity $e^- e^+$ colliders such as B-factories, with the ISR photon being emitted through the initial electron or positron, prior to their annihilation. The emitted $J/\Psi$ is produced through the photon fragmentation process, with the produced $J/\psi$ in turn decaying into a pair of leptons, $\mu^-+\mu^+$ through the leptonic decay process, $J/\Psi\rightarrow \gamma^*\rightarrow \gamma \mu^- \mu^+$. The cross section for the $J/\Psi$ production, and the branching ratio for the leptonic decay of $J/\Psi\rightarrow \mu^- \mu^+$, both calculated in the framework of Bethe-Salpeter equation are used to work out the cross section for the complete process, $e^- e^+ \rightarrow \gamma +J/\psi\rightarrow \gamma+\mu^- +\mu^+$. Our results are compared with the BaBar data, and other models. This study is then extended to production and decays of $\Upsilon(1S)$ through the ISR process.