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 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 perform a time-dependent Dalitz plot analysis of B0 → K0 S π+π- in order to extract the CP violation parameters of f0(980)K0 S and ρ0(770)K0 S and direct CP-asymmetries of Kz.ast;+(892)π-. The results are obtained from a data sample of (383 ± 3) × 106 BB decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The measured values of 2βeff in B0 decays to f0(980)K0S and ρ0(770)K0 S are (89+22-20 ± 5 ±8) and (37+19 -17 ± 5 ±6), respectively, where the first quoted uncertainty is statistical, the second is systematic and the third is Dalitz plot signal model uncertainty. We measure the significance of 2βeff (f0(980)K0S) 6= 0 to be 4.3 σ. In decays to Kz.ast;(892)π we find ACP = -0.18 ± 0.10 ± 0.03 ± 0.03. The measured phase difference between the decay amplitudes of B0 → Kz.ast;+(892)π- and B0 → Kz.ast;-(892)π+ is (-164 ± 24 ± 12 ± 15). All results are preliminary.