Jpsi invisible decay Edit Page

J/psi invisible analysis.

An invisible particle decay mode is defined as one where the final particles interact so weakly that there are no observables in general purpose particle detectors. Invisible decays of quarkonia such as J/psi etc., and other mesons provide a window on physics beyond the Standard Model (SM). This is because the only allowed invisible decay of quarkonium states in the SM is the decay to nunu via annihilation into a virtual Z0 boson. If the invisible decay rate is observed to have a larger branching fraction than the SM prediction, it implies physics beyond the SM. Invisible decays of some other particles have be studied.

Using 14.010^6 Psip events, the BESII experiment obtained a first upper limit, B(J/psi->invisible)/B(J/psi->mu+mu-)<1.210^-2, corresponding to B(J/psi->invisible)<710^-4 via the Psip->pi+pi-J/psi transition. We present here updated results of search for the invisible decay of the J/psi. The data sample used consists of 106.41+-0.8610^6 Psip events collected with the BESIII detector at the BEPCII collider.