Direct measurement of B(Dο→φΧο) and B(D+→φΧ+) -: art. no. 052001

The first measurement of B(D-0 --> phi X-0) and an upper limit for B(D+ --> phi X+) are determined from 22.3 pb(-1) of e(+)e(-) annihilation data at a c.m. energy of 4.03 GeV. The data were recorded by the Beijing Spectrometer (BES) at BEPC. A recoil charge method is applied to charm threshold data to determine the charge of the D meson in the recoil from 9054+/-309+/-416 reconstructed D-0, D+ mesons. The branching fractions B(D0 --> phi X-0) = (1.71(-0.71)(+0.76) +/- 0.17)%, and B(D+ --> phi X+) < 1.8% are determined from 10 events with a reconstructed D and a recoiling phi. In addition, a 90% C.L. upper limit of B(D+ --> phi e(+)X(0)) < 1.6% is determined from a search for semileptonic decays of the D+.