D_s Results from BES in 1994

From 1992 to 1994, BES has collected a data sample at 4.03 GeV with an integrated luminosity of 22.3 pb^{-1}. Among the work progress and results obtained in 1994 are:

Physicists in China and America have reached agreement on the method of particle identification, improved and finalized the analysis methods and cuts on single tag of $D_s/to/phi/pi, $K^{+}K, $K_{s}K. Wiht $phi/to/K^{+}K^{-}, $K^{*}/to/K/pi, $K_s/to/pi^{+}/pi^{-}, finalized the identification of mu, e, got the results of D_s purely leptonic decay and absolute branching fraction of $D_s/to/phi/pi. These two results were reported at Glasgow International Conference on High Energy Physics. At the end of the year, two papers were submitted to Physical Review Letters with the title of "A Direct Measurement of Pseudoscalsar Decay Constant $f_{D_s}" and "A Direct Measurement of the D_s Branching Fraction to $/phi/pi" . The main results are:

$f_{D_s}=4.3^{+1.5+0.4}_{-1.3-0.4}/times/10^2 MeV

and $B(D_s/to/phi/pi)=(3.9^{+5.1+1.8}_{-1.9-1.1}/%.

Some progress is also obtained in the ananysis of D_s semileptonic decay and the single tag of D_s decay to 5 prongs.

Li Weiguo

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Febrary 1995 BEPC News