B. Nemati

Measurement of the inclusive decay properties of charmed mesons

Abstract We report a high statistics study of the inclusive decay properties of the charmed D0 and D+ mesons, and the first inclusive study of the charmed Ds+. The data are collected at s =3.77 GeV and s =4.14 GeV with the Mark III detector at the e+e− storage ring SPEAR. For each charmed meson species, the charged-particle multiplicity, the strangeness content of the final state, and the average π0 multiplicity are determined.

Observation of a pseudoscalar state in near threshold

We present a study of the radiative decay J/ψ→γOO in the γK + K − K + K − and γK + K − K S 0 K L 0 final states. A pseudoscalar state is observed in the OO invariant-mass spectrum at 2.22 GeV/c 2 with a width of 150 MeV/c 2 . The product branching ratios are B(J/ψ→γX)B(X→OO)=(3.3±0.8±0.5)×10 −4 for the MeV/c γK + K − K + K − mode and B(J/ψ→γX)B(X→OO)=(2.7±0.6±0.6)×10 −4 for the γK + K − K S 0 K L 0 mode. No evidence for 2 ++ states below 2.4 GeV/c 2 is found in this decay

Measurement of the branching fractions for D0-e and D0K-ee and determination of Vcd/Vcs-2

Measurements of the exclusive branching fractions B(D^0→π^-e^+ν_e) and B(D^0→K^-e^+ν_e), using data collected at the ψ(3770) with the Mark III detector at the SLAC e^+e^- storage ring SPEAR, are used to determine the ratio of the Kobayashi-Maskawa matrix elements │V_(cd)/V_(cs)│^2 =0.057_(-0.015)^(+0.038)±0.005.

Search for the decay D0K0e+e-

A search for the decay of the charmed meson /ital D//sup 0//r arrow//bar K//sup 0/e/sup +/e/sup /minus// is presented, based on data collected at the /psi/(3770) resonance with the Mark III detector at the SLAC storage ring SPEAR. No evidence for this process is found, resulting in an upper limit on the decay branching ratio of 1.7/times/10/sup /minus/3/ at the 90% confidence level.