Experimental study of \etac decays into vector-vector final states

TL;DR

This study measures the branching fractions of  decays into vector-vector final states using 58 million J/3 events, providing new experimental data on these decay modes and setting upper limits for some channels.

Contribution

It provides the first precise measurements of   decay branching fractions into VV states with a large data sample, including new upper limits for unobserved channels.

Findings

Measured    decay branching fractions into , , , and  final states.

Set an upper limit for the   decay channel.

Provided constraints on   decay processes.

Abstract

Using 58 million J/\psi events accumulated with the BES II detector, branching fractions for the \eta_{c} ->VV decays, \eta_{c} -> \rho \rho, \eta_{c} -> K^{*}{\bar K}^{*}, \eta_{c} -> \omega \omega, and \eta_{c} -> \phi \phi, are measured. The branching fractions are Br(\eta_{c} -> \rho \rho) = (1.25 \pm 0.37 \pm 0.51) \times 10^{-2}, Br(\eta_{c} -> \K^{*}{\bar K}^{*}) = (10.4 \pm 2.6\pm 4.3) \times 10^{-3}, Br(\eta_{c} -> \omega\omega) < 6.3 \times 10^{-3} (90 % CL), and Br(\eta_{c} -> \phi \phi) = (2.5 \pm 0.5 \pm 0.9) \times 10^{-3}. The process \eta_{c} -> \omega\phi is also searched for, and the 90% CL upper limit Br(eta_{c} -> \omega\phi) < 1.3 \times 10^{-3} is obtained for this process.