Measurement of B(D_s+ -> mu+ nu_mu)/B(D_s+ -> phi mu+ nu_mu) and Determination of the Decay Constant f_{D_s}

K. Kodama, S. Torikai, N. Ushida +71

We have observed $23.2\pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^{+}->{\mu }^{+}{\nu }_{\mu }$ from a sample of muonic one prong decay events detected in the emulsion target of Fermila…