nan Sharma

Study of B→πlν and B→ρlν decays and determination of

We present an analysis of exclusive charmless semileptonic B-meson decays based on 377×106 BB pairs recorded with the BABAR detector at the Υ(4S) resonance. We select four event samples corresponding to the decay modes B0→π-l+ν, B+→π0l+ν, B0→ρ-l+ν, and B+→ρ0l+ν and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B→πlν samples, and similarly the two B→ρlν samples, and measure the branching fractions B(B0→π-l+ν)=(1.41±0.05±0.07)×10-4 and B(B0→ρ-l+ν)=(1.75±0.15±0.27)×10-4, where the errors are statistical and systematic. We compare the measured distribution in q2, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element |Vub|. Based on the measured partial branching fraction for B→πlν in the range q2<12  GeV2 and the most recent QCD light-cone sum-rule calculations, we obtain |Vub|=(3.78±0.13-0.40+0.55)×10-3, where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q2 range and the FNAL/MILC lattice QCD results, we obtain |Vub|=(2.95±0.31)×10-3 from B→πlν, where the error is the combined experimental and theoretical uncertainty.

Measurements of charged current lepton universality and

Using 467 fb(-1) of e(+)e(-) annihilation data collected with the BABAR detector, we measure B(tau(-)->mu(-)(nu) over bar (mu)nu(tau))/B(tau(-)-> e(-)(nu) over bar (e)nu(tau)) = (0.9796 +/- 0.0016 +/- 0.0036), B(tau(-)->pi(-)nu(tau))/B(tau(-)-> e(-)nu(e)nu(tau)) = (0.5945 +/- 0.0014 +/- 0.0061), and B(tau(-)-> K-nu(tau))/B(tau(-)-> e(-)nu(e)nu(tau)) = (0.03882 +/- 0.00032 +/- 0.00057), where the uncertainties are statistical and systematic, respectively. From these precision similar to measurements, we test the standard model assumption of mu - e and tau - mu charge current lepton universality and provide determinations of vertical bar V-us vertical bar experimentally independent of the decay of a kaon.

Measurement of B→Xγ decays and determination of

Using a sample of 383 X 10^6 BB events collected by the BABAR experiment, we measure sums of seven exclusive final states B → X_(d(s))Y, where X_d (Xs) is a nonstrange (strange) charmless hadronic system in the mass range 0:6–1:8 GeV/c^2. After correcting for unmeasured decay modes in this mass range, we obtain a branching fraction for b → dy of (7:2 ± 2:7(stat) ± 2:3(syst) X 10^(-6). Taking the ratio of X_d to X_s we find Г(b → dy)/Г(b → sy) = 0:033 ± 0:013(stat) ± 0:009(syst), from which we determine │V_(td)/V_(ts)│= 0:177 ± 0:043.

Measurements of B→{π,η,η′}lνl branching fractions and determination of

We report measurements of branching fractions for the decays B→P/ν/, where P are the pseudoscalar charmless mesons π-, π0, η and η′, based on 348fb-1 of data collected with the BABAR detector, using B0 and B+ mesons found in the recoil of a second B meson decaying as B→D(*)/ν/. Assuming isospin symmetry, we combine pionic branching fractions to obtain B(B0→π-/+ν/)=(1.54±0. 17(stat)±0.09(syst))×10-4; we find 3.2σ evidence of the decay B+→η/+ν/ and measure its branching fraction to be (0.64±0.20(stat)±0.03(syst))×10-4, and determine B(B+→η′/+ν/)<0.47×10-4 to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a variety of form factor calculation, we obtain values of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| in ranging from 3.6×10-3 to 4.1×10-3.

Study of B meson decays with excited η and η′ mesons - eScholarship

Using 383 x 10(6) BBover pairs from the BABAR data sample, we report results for branching fractions of six charged B-meson decay modes, where a charged kaon recoils against a charmless resonance decaying to KKover* or etapipi final states with mass in the range (1.2-1.8) GeV/c2. We observe a significant enhancement at the low KKover* invariant mass which is interpreted as B+-->eta(1475)K+, find evidence for the decay B+-->eta(1295)K+, and place upper limits on the decays B+-->eta(1405)K+, B+-->f1(1285)K+, B+-->f1(1420)K+, and B+-->phi(1680)K+.

Study of hadronic transitions between Υ states and observation of Υ(4S)→ηΥ(1S) decay - eScholarship

We present a study of hadronic transitions between Υ(mS) (m = 4, 3, 2) and Υ(nS) (n = 2, 1) resonances based on 347.5 fb^(-1) of data taken with the BABAR detector at the PEP-II storage rings. We report the first observation of Υ(4S) → ηΥ(1S) decay with a branching fraction [script B](Υ(4S) → ηΥ(1S)) = (1.96±0.06_(stat)±0.09_(syst))×10^(-4) and measure the ratio of partial widths Γ(Υ(4S) → ηΥ(1S))/Γ(Υ(4S) → π^+π^-Υ(1S))=2.41±0.40_(stat)±0.12_(syst). We set 90% CL upper limits on the ratios Γ(Υ(2S) → ηΥ(1S))/Γ(Υ(2S) → π^+π^-Υ(1S))<5.2×10^(-3) and Γ(Υ(3S) → ηΥ(1S))/Γ(Υ (3S) → π^+π^-Υ(1S))<1.9×10^(-2). We also present new measurements of the ratios Γ(Υ(4S) → π^+π^-Υ(2S))/Γ(Υ(4S) → π^+ π^-Υ(1S))=1.16±0.16_(stat)±0.14_(syst) and Γ(Υ(3S) → π^+π^-Υ(2S))/Γ(Υ(3S) → π^+ π^-Υ(1S))=0.577±0.026_(stat)±0.060_(syst).

Search for B0→K*+K*- - eScholarship

The authors report the results of a search for the decay B{sup 0} {yields} K*{sup +}K*{sup -} with a sample of 454 {+-} 5 million B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the Stanford Linear Accelerator Center. They obtain an upper limit at the 90% confidence level on the branching fraction for {Beta}(B{sup 0} {yields} K*{sup +}K*{sup -}) < 2.0 x 10{sup -6}, assuming the decay is fully longitudinally polarized.