First Experimental Study of the Purely Leptonic Decay Ds*+→’ e+ve

Using 7.33 fb(-1) of e(+)e(-) collision data taken with the BESIII detector at the BEPCII collider, we report the first experimental study of the purely leptonic decay D-s*(+) -> e(+)v(e). Our data contain a signal of this decay with a statistical significance of 2.9s. The branching fraction of D-s*(+) -> e(+)v(e) is measured to be (2.1(-0.9stat)(+1.2) +/- 0.2(syst)+ x 10(-5), corresponding to an upper limit of 4.0 x 10(-5) at the 90% confidence level. Taking the total width of the D-s*(+) [(0.070 +/- 0.028+ keV] predicted with the radiative D-s*(+) decay from the lattice QCD calculation as input, the decay constant of the D-s*(+) is determined to be f(Ds*+) = (214-(+61)(46stat) +/- 44(syst)) MeV, corresponding to an upper limit of 354 MeVat the 90% confidence level.
For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.141802