Georg Viehhauser

Abstract:

We report on the observation of B̄⁰→D* ⁰π⁺π⁺π^- π^-decays. The branching ratio is (0.30±0.07 ±0.06)%. Interest in this particular mode was sparked by Ligeti, Luke and Wise who propose it as a way to check the validity of factorization tests in B̄⁰→D*⁺π⁺π ^-π^-π⁰ decays. © 2001 The American Physical Society.

Abstract:

Using data collected by the CLEO detector in the γ(4S) region, we report new measurements of the exclusive decays of B mesons into final states of the type Λc+p̄n(π), where n= 0,1,2,3. We find signals in modes with one, two and three pions and an upper limit for the two-body decay Λc+p̄. We also make the first measurements of exclusive decays of B mesons to ∑cp̄n(π), where n = 0,1,2. We find signals in modes with one and two pions and an upper limit for the two-body decay ∑cp̄. Measurements of these modes shed light on the mechanisms involved in B decays to baryons. © 2002 The American Physical Society.

Abstract:

The ratio of charged and neutral B meson production at the γ(4S), f+-/f00, is measured through the decays B̄→D*ℓ^-ν̄ℓ, reconstructed using a partial reconstruction method where the D* is detected only through a pion daughter from the decay D*→Dπ. Using data collected by the CLEO II detector, the charged and neutral B decays are measured in such a way that their ratio is independent of the decay model, limited mainly by the uncertainty in the relative efficiency for detecting neutral and charged pions. This measurement yields the ratio of production fractions times the ratio of semileptonic branching fractions, f+-b+/f 00b0. Assuming that b+/b0 is equal to the lifetime ratio τ+/τ0 and using the world average value of τ+/τ0 as input, we obtain f +-/f00= 1.058±0.084±0.136. © 2002 The American Physical Society.

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.