We present a measurement of the branching fractions for B → D/D */D(*)πℓ-̄νℓ decays based on 341.1 fb-1 of data collected at the γ(4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We obtain B(B- → D0ℓ-̄νℓ) = (2.33 ± 0.09 (stat.) ± 0.09 (syst.))%, B(B- → D*0ℓ-̄νℓ) = (5.83±0.15 (stat.)±0.30 (syst.))%, B(B0 → D+ℓ-̄νℓ) = (2.21±0.11 (stat.)±0.12 (syst.))%, B(B0 → D*+ℓ-̄νℓ) = (5.49 ± 0.16 (stat.) ± 0.25 (syst.))%, B(B- → D+π-ℓ-̄νℓ) = (0.42 ± 0.06 (stat.) ± 0.03 (syst.))%, B(B- → D *+π-ℓ-̄νℓ) = (0.59±0.05 (stat.)±0.04 (syst.))%, B(B0 → D*π+ℓ- ̄νℓ) = (0.43±0.08 (stat.)±0.03 (syst.))% and B(B0 → D*0π+ℓ-̄νℓ) = (0.48±0.08 (stat.)±0.04 (syst.))%.

We study the decay B 0 → ρ 0 ρ 0 in a sample of about 427 million γ(4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e + e - collider at SLAC. We find the branching fraction B = (0.84 ± 0.29 ± 0.17) × 10-6 and longitudinal polarization fraction of fL = 0.70 ± 0.14 ± 0.05, where the first uncertainty is statistical, and the second is systematic. The evidence for the B 0 → ρ 0 ρ 0 signal has 3.6σ significance. We investigate the proper-time dependence of the longitudinal component in the decay and measure the CP-violating coefficients S00 L = (0.5± 0.9 ± 0.2) and C00 L = (0.4 ± 0.9 ± 0.2), corresponding to the sine and cosine terms in the time evolution of asymmetry. We study the implication of these results for penguin contributions in B → ρρ decays and for the CKM unitarity angle α.

We present a search for B decays to a charged scalar meson a0+ and a π0 where the a0+ decays to an η meson and a π+. The analysis was performed on a data sample consisting of 383×106 BB̄ pairs collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find no significant signal and set an upper limit on the product branching fraction B(B+→a0+π0)×B(a0+→ηπ+) of 1.4×10-6 at the 90% confidence level. © 2008 The American Physical Society.

We analyze the three-body charmless decay B±→K±K± K using a sample of 226.0±2.5 million BB̄ pairs collected by the BABAR detector. We measure the total branching fraction and CP asymmetry to be B=(35.2±0.9±1.6)×10-6 and ACP=(-1.7±2.6±1.5)%. We fit the Dalitz plot distribution using an isobar model and measure the magnitudes and phases of the decay coefficients. We find no evidence of CP violation for the individual components of the isobar model. The decay dynamics is dominated by the K+K- S-wave, for which we perform a partial-wave analysis in the region m(K+K-)<2GeV/c2. Significant production of the f0(980) resonance, and of a spin zero state near 1.55GeV/c2 are required in the isobar model description of the data. The partial-wave analysis supports this observation. © 2006 The American Physical Society.

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-CP0K-)/B(B- → D*non-CP0π-) = 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.

We present the first measurement of the B0 → X-u ℓ+νℓ partial branching fraction in the endpoint region of the lepton momentum spectrum, above the threshold for B → Xcℓνℓ decays. The analysis is based on a sample of 383 million γ(4S) decays into BB pairs collected with the BABAR detector at the PEP-II e+e- storage rings. We select B0B0 events by partially reconstructing one B meson via the B0 → Dz.ast;+ℓ- ̄νℓ decays then select B0 → X- u ℓ+νℓ decays identifying a second high momentum lepton. In the momentum interval ranging from 2.3 to 2.6 GeV/c we measure the partial branching fraction πB(B0 → Xuℓν) = (1.30 ± 0.21stat ± 0.07syst) × 10-4 where the first error is statistical and the second is systematic. By comparing this measurement with the one obtained from untagged B decays we obtain R+/0 = ΔB(B0 → Xuℓν)/ ΔB(B+ → Xuℓν) = 1.18 ± 0.35stat ± 0.17syst. Using this measurement we extract a limit on the contributions from processes breaking isospin symmetry in charmless semileptonic B decays.

We present a preliminary study of B- → D 0 (CP)π- and B- → D 0 (CP)K- decays, with the D 0 (CP)reconstructed in the CP-odd eigenstates Ksπ0, Ks, in the CP-even eigenstates K+K-, π+π-, and in the (non-CP) flavor eigenstate K ± π ± . Using a sample of about 382 million γ(4S) decays into BB pairs, collected with the BABAR detector operating at the PEP-II asymmetric-energy B Factory at SLAC, we measure the ratios of the branching fractions B(B- → D 0 CP±K-) + B(B+ → D 0 CP±K+) [B(B- → D 0 K-) + B(B+ → D 0 K+)]/2 and the direct CP asymmetry ACP± Ξ B(B-→D 0 CP±K-) - B(B+→D 0 CP±K+) B(B-→D 0 CP±K-) + B(B+→D 0 CP±K+) . The results are: RCP- = 0.81 ± 0.10(stat) ± 0.05(syst) RCP+ = 1.07 ± 0.10(stat) ± 0.04(syst) ACP- = -0.19 ± 0.12(stat) ± 0.02(syst) ACP+ = 0.35 ± 0.09(stat) ± 0.05(syst).

We present preliminary results of a search for B → Xdγ decays with a hadronic mass 1.0 GeV/c2 < M(Xd) < 1.8 GeV/c2. We consider seven final states with up to four charged pions and one neutral pion or η, which correspond to about 50% of the total Xd fragmentation in this mass range. Based on a sample of 383 million B ̄B events collected by the BaBar experiment at PEPII, we measure a partial branching fraction P7 Xd=1 B(B → Xdγ)|(1.0GeV/c2 < M(Xd) < 1.8GeV/c2) = (3.1±0.9+0.6 -0.5 ±0.5) · 10-6, where the uncertainties are statistical, systematic and model-dependent respectively.

We present a search for the rare B-meson decay B0→a1±ρ with a1±→π+π-π±. We use (110±1.2) ×106Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We obtain an upper limit of 30×10-6(90%C.L.) for the branching fraction product B(B0→a1± ρ)B(a1±→π+π-π±), where we assume that the a1± decays exclusively to ρ0π±. © 2006 The American Physical Society.

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.