Direct Measurement of the Pseudoscalar Decay Constant,fDs

Direct measurement of the pseudoscalar decay constant, fDs.

J.Z. Bai, 1 0. Bardon,6 1. Blum,11 A. Breakstone,9 T. Bumett, 12 G.P. Chen, 1 H. F. Chen,4 J. Chen,5 S.J. Chen, 1 S.M. Chen, 1 Y. Chen, 1 Y.B. Chen, 1 Y.Q. Chen, 1 B.S. Cheng,1 R.F. Cowan,6 H. C. Cui, 1 X.Z. CuV H.L. Ding,1 Z.Z. Du, 1 W. Dunwoodie,8 X.L. Fan, 1 J. Fang, 1 M. Fero,6 C.S. Gao, 1 M.L. Gao,1 S.Q. Gao,1 W.X. Gao, 1 P. Gratton, 11 J.H. Gu, 1 S.D. Gu, 1 W.X. Gu, 1 Y.F. Gu, 1 Y.N. Guo,...

Measurement of the Pseudoscalar Decay Constant

Improved measurement of the pseudoscalar decay constant fDs

Improved measurement of B(D+ --> mu+nu) and the pseudoscalar decay constant fD+.

We extract a relatively precise value for the decay constant of the meson by measuring B(D+ --> mu+nu) = (4.40 +/-0.66(+0.09)(-0.12) x 10(-4) using 281 pb(-1) of data taken on phi(3770) the resonance with the CLEO-c detector. We find fD+ = (222.6 +/- 16.7(+2.8)(-3.4)) MeV, and compare with current theoretical calculations. We also set a 90% confidence upper limit on B(D+e+nu)< 2.4 x 10(-5) whic...

Two-photon decay of pseudoscalar quarkonia

We report on our recent evaluation of the two-photon width of the pseudoscalar quarkonia, ηc(nS) and ηb(nS) in an approach based on Heavy-Quark Spin Symmetry (HQSS). To what concerns the 1S state ηc, our parameter-free computation agrees with experiments, as well as most of other theoretical works. On the other hand, our computation for the 2S-state looks 2S like a confirmation that there may e...