Measurements of Cabibbo-suppressed hadronic decays of charmed D+ and D0 mesons.
نویسندگان
چکیده
Measurements of the branching ratios of ten Cabibbo suppressed hadronic weak decays of the II+ and Do are presented from data collected with the Mark III detector at SPEAR. In addition to the previously observed channels Do-) K-K+ and T-T+, we report new measurements of Do + r-rr+~O and ?r-n+rr-7rlr+; We present measurements of Cabibbo suppressed hadronic weak decays of the D+ and Do into two, three and four-body final states. Measurements of D+ and Do semileptonic branching fractions (B$ and Bt) " " " as well as direct decay length measurements,@] indicate a substantial difference between D+ and Do lifetimes. The magnitudes of Bz and Bz suggest the presence of distinct nonleptonic processes which enhance the Do and suppress the D+ width. " ' Thus, a further understanding of the D decay mechanism requires a systematic study of the hadronic decays. The measurements we report address three aspects of these decays: the contribution of Cabibbo suppressed decays to the total widths of the D+ and Do, the importance of interference between final state amplitudes in the Ds decays, and the presence of non-perturbative effects in both the D+ and Do decays. The data were collected near the peak of the $(3770) resonance with the Mark III detector at the e'e-storage ring SPEAR. The detector has been described in detail elsewhere. I51 The sample of events corresponds to an integrated luminosity of 8.7 pb-', or about 50,000 produced DD pairs. The analyses of the Cabibbo favored Do decay to K-r+, and the suppressed decays to ?r-n+ and K-K+ proceed as follows: all charged tracks are required to originate within a fiducial volume of radius 30mm and length 160mm centered on the interaction point. They also must lie within the region covered by the time-of-flight (TOF) system, 1 cos81 5 0.76 (where 8 is the polar angle). The two-body decays of the Do produce at least one track with a large momentum (-1 GeV/c), for which r/K misidentification becomes significant. We therefore employ a technique which separates the signal and misidentification peaks within 2 a single plot by taking advantage of the threshold production of the Dobo pairs. At threshold, the invariant mass of pairs of tracks arising from real K-rr+ decays is insensitive to the interchange of the 7~ and K particle assignments, while a single misidentification results in a narrow reflection peak separated by ho.120 GeV/c2 from the Do …
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ورودعنوان ژورنال:
- Physical review letters
دوره 55 2 شماره
صفحات -
تاریخ انتشار 1985