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

Abstract

We study the Initial state radiation (ISR) process, $e^{-}{e}^{+}{\to }^{\ast }\gamma \to \gamma +J/\psi$ 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, $J/\Psi \to {\gamma }^{\ast }\to \gamma {\mu }^{-}{\mu }^{+}$. The cross section for the $J/\Psi$ production, and the branching ratio for the leptonic decay of $J/\Psi \to {\mu }^{-}{\mu }^{+}$, both calculated in the framework of Bethe-Salpeter equation are used to work out the cross section for the complete process, $e^{-}{e}^{+}\to \gamma +J/\psi \to \gamma +{\mu }^{-}+{\mu }^{+}$. Our results are compared with the BaBar data, and other models. This study is then extended to production and decays of ${\rm Y}(1S)$ through the ISR process.

Comments: 18 pages, 3 figures, 4 tables