LHCb

Abstract:

We study the decays B- → D*0π - and B-→ D*0K-, where the D*0 decays into D0π0, with the D0 reconstructed in the CP-even (CP+) eigenstates K-K + and π-π+ and in the (non-CP) channels K-π+, K -π+π+π-, and K -π+π0. Using a sample of about 123 × 106 BB̄ pairs, we measure the ratios of decay rates R*non-CP ≡ B(B- → D* non-CP 0K-)/B(B- → D*non-CP 0π-) = 0.086 ± 0.0040(stat)-0.0031 +0.0042(syst), and provide the first measurements of R*CP+ ≡ B(B- → D*CP+ 0K-)/B(B- → D*CP+ 0π-) = 0.0086 ± 0.021(stat) ± 0.007(syst), and of the CP asymmetry A*CP+ ≡ B(B- → D*CP+ 0K -)-B(B+ → D*CP+ 0K +)/B(B- → D*CP+ 0K -)+B(B+ → D*CP+ 0K +) = 0.10 ± 0.23(stat)-0.04 +0.03(syst). © 2005 The American Physical Society.

Abstract:

We describe searches for B meson decays to the charmless vector-vector final states ωK* and ωρ in 89 × 106 BB̄ pairs produced in e+e- annihilation at √s = 10.58 GeV. We measure the following branching fractions in units of 10 -6: B(B0 → ωK*0) = 3.4 -1.6 +1.8 ± 0.4(<6.0), B(B+ → ωK*+) = 3.5-2.0 +2.5 ± 0.7(<7.4), B(B0 → ωρ0) = 0.6 -1.1 +1.3 ± 0.4(<3.3), and B(B+ → ωρ+) = 12.6-3.3 +3.7 ± 1.6. The first error quoted is statistical, the second systematic, and the upper limits are defined at 90% confidence level. For B+ → ωρ+ we also measure the longitudinal spin alignment fraction fL = 0.88-0.15 +0.12 ± 0.03 and charge asymmetry Ach = (5 ± 26 ± 2)%. © 2005 The American Physical Society.

Abstract:

We search for a charged partner of the X(3872) in the decay B → X - K, X- → J/ψπ-π0, using 234 × 106 BB events collected at the Y(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric-energy storage ring. The resulting product branching fraction upper limits are B(B 0 → X- K+, X- → J/ψπ-π0) < 5.4 × 10-6 and B(B- → X-K̄0, X- → J/ψπ-π0) < 22 × 10-6 at the 90% confidence level. © 2005 The American Physical Society.

Abstract:

We present results on B → J/ψKπ decays using e+ e- annihilation data collected with the BABAR detector at the Y(4S) resonance. The detector is located at the PEP-II asymmetric-energy storage ring facility at the Stanford Linear Accelerator Center. Using approximately 88 × 106 BB̄ pairs, we measure the decay amplitudes for the flavor eigenmodes and observe strong-phase differences indicative of final-state interactions with a significance of 7.6 standard deviations. We use the interference between the Kπ S-wave and P-wave amplitudes in the region of the K*(892) to resolve the ambiguity in the determination of these strong phases. We then perform an ambiguity-free measurement of cos2β using the angular and time-dependent asymmetry in B → J/ψK* 0(KS 0π0) decays. With sin2β fixed at its measured value and cos2β treated as an independent parameter, we find cos2β = 2.72-0.79 +0.50(stat) ± 0.27(syst), determining the sign of cos2β to be positive at 86% C.L. © 2005 The American Physical Society.