Measurement of \chi_{c2} Production in Two-Photon Collisions

TL;DR

This paper reports the measurement of the _{2} charmonium state production in two-photon collisions using the Belle detector, providing precise values for its decay width and branching fractions in electron-positron collisions.

Contribution

It presents the first measurement of _{2} production in two-photon collisions with detailed decay width and branching fraction results.

Findings

Measured _{2} two-photon decay width times branching fraction as 13.5 1.3(stat.) 1.1(syst.) eV.

Observed a clear _{2} signal in 32.6 fb^{-1} data sample.

Demonstrated the feasibility of studying charmonium states in two-photon processes.

Abstract

The production of the \chi_{c2} charmonium state in two-photon collisions has been measured with the Belle detector at the KEKB e^+e^- collider. A clear signal for \chi_{c2} --> \gamma J/\psi, J/\psi --> l^+l^- is observed in a 32.6fb^{-1} data sample accumulated at center-of-mass energies near 10.6GeV, and the product of its two-photon decay width and branching fraction is determined to be \Gamma_{\gamma\gamma}(\chi_{c2})B(\chi_{c2} --> \gamma J/\psi) B(J/\psi --> l^+l^-)= 13.5 +/- 1.3(stat.) +/- 1.1(syst.)eV.