Using a sample of 232×106 Υ(4S)→BB̄ events collected with the BABAR detector at the PEP-II B Factory in 1999-2004, we study B-→D0K*(892)- decays where K*-→KS0π- and D0→K-π+, K-π+π0, K-π+π+π- (non-CP final states); K+K-, π+π- (CP+ eigenstates); KS0π0, KS0, and KS0ω (CP- eigenstates). We measure four observables that are sensitive to the angle γ of the CKM unitarity triangle; the partial-rate charge asymmetries ACP± and the ratios of the B-decay branching fraction in CP± and non-CP decays RCP±: ACP+=-0.08±0.19(stat)±0.08(syst), ACP-=-0.26±0.40(stat)±0.12(syst), RCP+=1.96±0.40(stat) ±0.11(syst), and RCP-=0.65±0.26(stat)±0.08(syst). © 2005 The American Physical Society.

© 2015 American Physical Society. We present a search for a neutral, long-lived particle L that is produced in e∧{+}e∧{-} collisions and decays at a significant distance from the e∧{+}e∧{-} interaction point into various flavor combinations of two oppositely charged tracks. The analysis uses an e∧{+}e∧{-} data sample with a luminosity of 489.1 fb∧{-1} collected by the BABAR detector at the Υ(4S), Υ(3S), and Υ(2S) resonances and just below the Υ(4S). Fitting the two-track mass distribution in search of a signal peak, we do not observe a significant signal, and set 90% confidence level upper limits on the product of the L production cross section, branching fraction, and reconstruction efficiency for six possible two-body L decay modes as a function of the L mass. The efficiency is given for each final state as a function of the mass, lifetime, and transverse momentum of the candidate, allowing application of the upper limits to any production model. In addition, upper limits are provided on the branching fraction B(B→X-{s}L), where X-{s} is a strange hadronic system.

The branching fraction of the τ-→3h-2h+ντ decay (h=π,K) is measured with the BABAR detector to be (8.56±0.05±0.42) ×10-4, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the ρ resonance playing a strong role. The decay τ-→f1(1285)π-ντ, with the f1(1285) meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9±0.7±0.5)×10-4. © 2005 The American Physical Society.

© 2017 American Physical Society. We report a Dalitz plot analysis of charmless hadronic decays of charged B mesons to the final state KS0π+π0 using the full BABAR data set of 470.9±2.8 million BB events collected at the ϒ(4S) resonance. We measure the overall branching fraction and CP asymmetry to be B(B+→K0π+π0)=(31.8±1.8±2.1-0.0+6.0)×10-6 and ACP(B+→K0π+π0)=0.07±0.05±0.03-0.03+0.02, where the uncertainties are statistical, systematic, and due to the signal model, respectively. This is the first measurement of the branching fraction for B+→K0π+π0. We find first evidence of a CP asymmetry in B+→K∗(892)+π0 decays: ACP(B+→K∗(892)+π0)=-0.52±0.14±0.04-0.02+0.04. The significance of this asymmetry, including systematic and model uncertainties, is 3.4 standard deviations. We also measure the branching fractions and CP asymmetries for three other intermediate decay modes.

© 2016 American Physical Society. We describe in detail a previously published measurement of CP violation in B0-B¯0 oscillations, based on an integrated luminosity of 425.7 fb-1 collected by the BABAR experiment at the PEPII collider. We apply a novel technique to a sample of about 6 million B¯0→D∗+-ν¯ decays selected with partial reconstruction of the D∗+ meson. The charged lepton identifies the flavor of one B meson at its decay time, the flavor of the other B is determined by kaon tagging. We determine a CP violating asymmetry ACP=(N(B0B0)-N(B¯0B¯0))/(N(B0B0)+N(B¯0B¯0))=(0.06±0.17-0.32+0.38)% corresponding to ΔCP=1-|q/p|=(0.29±0.84-1.61+1.88)×10-3. This measurement is consistent and competitive with those obtained at the B factories with dilepton events.

We present evidence for the bâ†d penguin-dominated decays B+â†KÂ0K+ and B0â†K0KÂ0 in 227Ã-106 Î¥(4S)â†'BBÂdecays collected with the BABAR detector. We measure the branching fractions B(B+â†'KÂ0K+)= (1.5±0.5±0.1)Ã-10-6(<2.4Ã-10-6) and B(B0â†'K0KÂ0)=(1.19-0.35+0.40±0.13) Ã-10-6, where the uncertainties are statistical and systematic, respectively. We also present improved measurements of the charge-averaged branching fraction B(B+â†'K0Ï€+)=(26.0±1. 3±1.0)Ã-10-6 and CP-violating charge asymmetry ACP(K0Ï€+)=-0.09±0.05±0.01, where the uncertainties are statistical and systematic, respectively. © 2005 The American Physical Society.

© 2016 American Physical Society. We report on measurements of the decays of B¯ mesons into the semileptonic final states B¯→D(∗)π+π-ν¯, where D(∗) represents a D or D∗ meson and - is an electron or a muon. These measurements are based on 471×106 BB¯ pairs recorded with the BABAR detector at the SLAC asymmetric B factory PEP-II. We determine the branching fraction ratios Rπ+π-(∗)=B(B¯→D(∗)π+π-ν¯)/B(B¯→D(∗)-ν¯) using events in which the second B meson is fully reconstructed. We find Rπ+π-=0.067±0.010±0.008 and Rπ+π-∗=0.019±0.005±0.004, where the first uncertainty is statistical and the second is systematic. Based on these results and assuming isospin invariance, we estimate that B¯→D(∗)ππ-ν¯ decays, where π denotes either a π± and π0 meson, account for up to half the difference between the measured inclusive semileptonic branching fraction to charm hadrons and the corresponding sum of previously measured exclusive branching fractions.

We present the first measurement of Υ(4S) decays to π+π-Υ(1S) and π+π-Υ(2S) based on a sample of 230×106Υ(4S) mesons collected with the BABAR detector. We measure the product branching fractions B(Υ(4S)→π+π-Υ(1S)) ×B(Υ(1S)→μ+μ-)=(2.23±0.25stat±0.27syst) ×10-6 and B(Υ(4S)→π+π-Υ(2S))×B(Υ(2S) →μ+μ-)=(1.69±0.26stat±0.20syst)×10-6, from which we derive the partial widths Γ(Υ(4S)→π+π-Υ(1S))=(1. 8±0.4)keV and Γ(Υ(4S)→π+π-Υ(2S))=(2. 7±0.8)keV. © 2006 The American Physical Society.

We perform a search for the exclusive radiative decay B0→γ, which is dominated by b̄d annihilation, in a sample of 124×106 BB̄ events collected with the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring at SLAC. No significant signal is seen. We set an upper limit on the branching fraction of B(B0→γ)<8. 5×10-7 at the 90% confidence level. © 2005 The American Physical Society.

We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energye+e-collider at the γ(4S), γ(3S), and γ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by countinge+e-→e+e-and (for the γ(4S) only)e+e-→μ+μ-candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections ofe+e-→e+e-ande+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the γ(3S) and γ(2S) resonances, an additional uncertainty arises due to γ→e+e-X background. For data collected off the γ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the γ(4S), 0.58% (0.72%) for the γ(3S), and 0.68% (0.88%) for the γ(2S). © 2013 Elsevier B.V.