Georg Viehhauser

Abstract:

We present new measurements of branching fractions for the color-favored decays B+ → D0π- and B̄0 → D+π-. Using 9.67×106 BB̄ pairs collected with the CLEO detector, we obtain the branching fractions Β(B- → D0π - = (49.7±1.2±2.9±2.2)×104 and Β(B̄0 → D+π-) = (26.8±1.2±2.4±1.2)×10-4. The first error is statistical, the second is systematic, and the third is due to the experimental uncertainty on the production ratio of charged and neutral B mesons in Y(4S) decays. These results, together with the current world average for the color-suppressed branching fraction Β(B̄+ → D 0π0), are used to determine the cosine of the strong phase difference δI between the I = 1/2 and I=3/2 isospin amplitudes. We find cos δI = 0.863 -0.023-0.035-0.030+0.024+0.036+0.038, and obtain a 90% confidence interval of 16.5° < δI < 38.1°. This nonzero value of δI suggests the presence of final state interactions in the D π system. © 2002 The American Physical Society.

Abstract:

We have searched for the charmless hadronic decay of B0 mesons into two neutral pions. Using 9.13 fb-1 taken at the Y(45) with the CLEO detector, we obtain an improved upper limit for the branching fraction B(B0 → π0π0)<5.7×10 -6 at the 90% confidence level. © 2002 The American Physical Society.

Abstract:

We have searched for lepton flavor violating decays of the τ lepton with one or two KS⁰ mesons in the final state. The data used in the search were collected with the CLEO II and II.V detectors at the Cornell Electron Storage Ring (CESR) and correspond to an integrated luminosity of 13.9 fb^-1 at the Y (4S) resonance. No evidence for signals were found; therefore, we have set 90% confidence level (C.L.) upper limits on the branching fractions Β(τ^- → e^- K S⁰)<9.1×10^-7, Β(τ^- →μ^- KS⁰)<9.5×10^-7, Β(τ^- → e^-KS⁰K S⁰) <2.2× 10^-6, and Β(τ^- → μ^- KS⁰K S⁰)<3.4×10^-6. These represent significantly improved upper limits on the two-body decays and first upper limits on the three-body decays. © 2002 The American Physical Society.