9 research outputs found
Evidence for the h_b(1P) meson in the decay Upsilon(3S) --> pi0 h_b(1P)
Using a sample of 122 million Upsilon(3S) events recorded with the BaBar
detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we search for
the spin-singlet partner of the P-wave chi_{bJ}(1P) states in the
sequential decay Upsilon(3S) --> pi0 h_b(1P), h_b(1P) --> gamma eta_b(1S). We
observe an excess of events above background in the distribution of the recoil
mass against the pi0 at mass 9902 +/- 4(stat.) +/- 2(syst.) MeV/c^2. The width
of the observed signal is consistent with experimental resolution, and its
significance is 3.1sigma, including systematic uncertainties. We obtain the
value (4.3 +/- 1.1(stat.) +/- 0.9(syst.)) x 10^{-4} for the product branching
fraction BF(Upsilon(3S)-->pi0 h_b) x BF(h_b-->gamma eta_b).Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D (Rapid
Communications
Searches for rare or forbidden semileptonic charm decays
We present searches for rare or forbidden charm decays of the form X(c)(+) -> h(+/-)l(+/-)l((l)+), where X(c)(+) is a charm hadron (D(+), D(s)(+), or A(c)(+)), h +/- is a pion, kaon, or proton, and l((l)+/-) is an electron or muon. The analysis is based on 384 fb(-1) of e(+)e(-) annihilation data collected at or close to the gamma(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the 35 decay modes that are investigated. We establish 90% confidence-level upper limits on the branching fractions between 1 x 10(-6) and 44 x 10(-6) depending on the channel. In most cases, these results represent either the first limits or significant improvements on existing limits for the decay modes studied
A study of radiative bottomonium transitions using converted photons
19 pages, 7 figures, submitted to Phys. Rev. DWe use 111+/-1 million Upsilon(3S) and 89+/-1 million Upsilon(2S) events recorded by the BaBar detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e+e- pairs by the detector material. We observe Upsilon(3S) -> gamma chi_b0,2(1P) decay, make precise measurements of the branching fractions for chi_b1,2(1P,2P) -> gamma Upsilon(1S) and chi_b1,2(2P) -> gamma Upsilon(2S) decays, and search for radiative decay to the eta_b(1S) and eta_b(2S) states
Analysis of the D^{+}âK^{-}Ï^{+}e^{+}Îœ_{e} decay channel
Using 347.5ââfb-1 of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244Ă103 signal events for the D+âK-Ï+e+Îœe decay channel are analyzed. This decay mode is dominated by the KÌ
*(892)0 contribution. We determine the KÌ
*(892)0 parameters: mK*(892)0=(895.4±0.2±0.2)ââMeV/c2, ÎK*(892)00=(46.5±0.3±0.2)ââMeV/c2, and the Blatt-Weisskopf parameter rBW=2.1±0.5±0.5ââ(GeV/c)-1, where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q2=0 (rV=V(0)/A1(0)=1.463±0.017±0.031, r2=A2(0)/A1(0)=0.801±0.020±0.020) and the value of the axial-vector pole mass parametrizing the q2 variation of A1 and A2: mA=(2.63±0.10±0.13)ââGeV/c2. The S-wave fraction is equal to (5.79±0.16±0.15)%. Other signal components correspond to fractions below 1%. Using the D+âK-Ï+Ï+ channel as a normalization, we measure the D+ semileptonic branching fraction: B(D+âK-Ï+e+Îœe)=(4.00±0.03±0.04±0.09)Ă10-2, where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A1 at q2=0: A1(0)=0.6200±0.0056±0.0065±0.0071. Fixing the P-wave parameters, we measure the phase of the S wave for several values of the KÏ mass. These results confirm those obtained with KÏ production at small momentum transfer in fixed target experiments
Measurements of branching fractions, polarizations, and direct CP-violation asymmetries in B^{+}âÏ^{0}K^{*+} and B^{+}âf_{0}(980)K^{*+} decays
We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B+âÏ0K*+ and B+âf0(980)K*+ with a sample of (467±5)Ă106BBÌ
pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. We observe B+âÏ0K*+ with a significance of 5.3Ï and measure the branching fraction B(B+âÏ0K*+)=(4.6±1.0±0.4)Ă10-6, the longitudinal polarization fL=0.78±0.12±0.03, and the CP-violation asymmetry ACP=0.31±0.13±0.03. We observe B+âf0(980)K*+ and measure the branching fraction B(B+âf0(980)K*+)ĂB(f0(980)âÏ+Ï-)=(4.2±0.6±0.3)Ă10-6 and the CP-violation asymmetry ACP=-0.15±0.12±0.03. The first uncertainty quoted is statistical and the second is systematic
Studies of Ï-âηK-ÎœÏ and Ï-âηÏ-ÎœÏ at BABAR and a search for a second-class current
We report on analyses of tau lepton decays Ï-âηK-ÎœÏ and Ï-âηÏ-ÎœÏ, with ηâÏ+Ï-Ï0, using 470ââfb-1 of data from the BABAR experiment at PEP-II, collected at center-of-mass energies at and near the ΄(4S) resonance. We measure the branching fraction for the Ï-âηK-ÎœÏ decay mode, B(Ï-âηK-ÎœÏ)=(1.42±0.11(stat)±0.07(syst))Ă10-4, and report a 95% confidence level upper limit for the second-class current process Ï-âηÏ-ÎœÏ, B(Ï-âηÏ-ÎœÏ)<9.9Ă10-5