# ICHEP2012

4-11 July 2012
Melbourne Convention and Exhibition Centre
Australia/Melbourne timezone
ICHEP2012 - 36th International Conference for High Energy Physics

## Two-photon collisions at Belle

5 Jul 2012, 15:30
15m
Room 220 (Melbourne Convention and Exhibition Centre)

### Room 220

#### Melbourne Convention and Exhibition Centre

Melbourne Australia
Parallel Sessions Track 7. CP Violation, CKM, Rare Decays, Meson Spectroscopy

### Speaker

Dr Hideyuki Nakazawa (National Central University)

### Description

The invariant mass spectrum of the $\eta' \pi^+ \pi^-$ final state produced in two-photon collisions is obtained using 673 fb$^{-1}$ of data on and off the $\Upsilon(4S)$ collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The $\eta_c$ mass, width and the product of the two-photon width and the branching fraction of the decay into $\eta' \pi^+ \pi^-$ are measured. We also report the first evidence for the $\eta(1760)$ decays to $\eta' \pi^+\pi^-$. From a fit of the mass spectrum with the coherent $X(1835)$ and $\eta(1760)$ resonances, we set a 90% confidence level upper limit on the product $\Gamma_{\gamma\gamma} {\cal B}$ for the $X(1835)$.

### Primary author

Dr Hideyuki Nakazawa (National Central University)

 Slides