Speaker
Mr
Andrey Sukharev
(BINP)
Description
Based on the nine data sets taken with the KEDR detector since 2004 in charmonia region, we report $\Gamma_{ee} \times \mathcal{B}_{\mu\mu} = 19.4 \pm 0.3 \pm 0.4$ eV for $\psi(2s)$ meson. The total luminosity accounted for is more than 6.5 pb$^{-1}$, corresponding to about $4 \times 10^6 \psi(2s)$.
There were several scans of the resonance allowing us to know the collider energy spread and several runs where the data was taken at the $\psi(2s)$ peak and slightly below it.
The Particle Data Group does not mention any direct measurement of this quantity yet. Instead, many $\psi(2s)$ parameters, including partial widths and branching ratios, are obtained using a complicated simultaneous fit of results of various experiments.
Primary author
Mr
Andrey Sukharev
(BINP)
