arXiv subjects
Publications and source records attributed to B. Aubert.
We describe searches for decays of B mesons to the charmless final states eta' eta' K. The data consist of 228 million B Bbar pairs produced in e+ e- annihilation, collected with the BaBar detector at the Stanford Linear Accelerator Center. The 90% confidence level upper limits for the branching fractions are Br(B0->eta' eta' K0)<31 10^{-6} and Br(B+->eta' eta' K+)<25 10^{-6}.
We analyze the three-body charmless decay B+- -> K+-K+-K-+ using a sample of 226.0 +- 2.5 million BBbar pairs collected by the BABAR detector. We measure the total branching fraction and CP asymmetry to be B = (35.2 +- 0.9 +-1.6) x 10^{-6} and A_CP = (-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-) < 2 GeV/c^2. Significant production of the f0(980) resonance, and of a spin zero state near 1.55 GeV/c^2 are required in the isobar model description of the data. The partial-wave analysis supports this observation.
We present the first measurement of $Υ(4S)$ decays to $π^+pi^-Υ(1S)$ and $π^+pi^-Υ(2S)$ based on a sample of 230$\times10^6$ $Υ(4S)$ mesons collected with the BABAR detector. We measure the product branching fractions ${\cal B}(Υ(4S)\to π^+pi^-Υ(1S))\times{\cal B}(Υ(1S)\toμ^+μ^-)=(2.23\pm0.25_{stat} \pm0.27_{sys})\times 10^{-6}$ and ${\cal B}(Υ(4S)\to π^+pi^-Υ(2S))\times{\cal B}(Υ(2S)\toμ^+μ^-)=(1.69\pm0.26_{stat}\pm0.20_{sys})\times 10^{-6}$, from which we derive the partial widths $Γ(Υ(4S)\to π^+pi^-Υ(1S))=(1.8\pm0.4)$~keV and $Γ(Υ(4S)\to π^+pi^-Υ(2S))=(2.7\pm0.8)$~keV.
From a sample of 232 million Upsilon(4S)--> B B-bar events collected with the BABAR detector at the PEP-II B Factory in 1999--2004, we measure the B- --> D0 K*-(892) decay branching fraction using events where the K*- is reconstructed in the K0_S pi- mode and the D0 in the K- pi+, K- pi+ pi0, and K- pi+ pi+ pi- channels: B(B- --> D0 K*-(892)) = 5.29 +/- 0.30(stat) +/- 0.34 (syst)) X 10-4.
We present a study of the decays B0bar --> D(*)0 K(*)0bar using a sample of 226 million Y(4S) --> B Bbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e-collider at SLAC. We report evidence for the decay of B0 and B0bar mesons to the D*0 K0s final state with an average branching fraction BF(B0-tilde --> D*0 K0bar) := [ BF(B0bar --> D*0 K0bar) + BF(B0 --> D*0 K0) ]/2 = (3.6 +- 1.2 +- 0.3) x 10^-5. Similarly, we measure BF(B0-tilde --> D0 K0bar) := [ BF(B0bar --> D0 K0bar) + BF(B0 --> D0 K0) ]/2 = (5.3 +- 0.7 +- 0.3) x 10^-5 forthe D0 K0s final state. We measure BF(B0bar --> D0 K*0bar) =^(4.0 +- 0.7 +- 0.3) x 10^-5 and set a 90% confidence level upper limit BF(B0bar --> D0bar K*0bar) < 1.1 x 10^-5. We determine the upper limit for the decay amplitude ratio |A(B0bar --> D0bar K*0bar)/A(B0bar --> D0 K*0bar)| to be less than 0.4 at the 90% confidence level.
A search for the decay of the tau lepton to five charged and two neutral pions is performed using data collected by the BABAR detector at the PEP-II asymmetric-energy e+e- collider. The analysis uses 232 fb-1 of data at center-of-mass energies on or near the Y(4S) resonance. We observe 10 events with an expected background of 6.5^{+2.0}_{-1.4} events. In the absence of a signal, we set the limit on the branching ratio B(tau- --> 3pi- 2pi+ 2pi0 nu_tau) < 3.4x10^{-6} at the 90% confidence level. This is a significant improvement over the previously established limit. In addition, we search for the decay mode tau- --> 2omega pi- nu_tau. We observe 1 event with an expected background of 0.4^{+1.0}_{-0.4} events and calculate the upper limit B(tau- --> 2omega pi- nu_tau) < 5.4x10^{-7} at the 90% confidence level. This is the first upper limit for this mode.
We report the observation of decays B0->D_s(*)+pi- and B0->D_s(*)-K+ in a sample of 230*10^6 Upsilon(4S)->BBbar events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- storage ring. We measure the branching fractions B(B0->D_s+pi-)=(1.3 +/- 0.3 (stat.) +/- 0.2 (syst.))*10^{-5}, B(B0->D_s-K+)=(2.5 +/- 0.4 (stat.) +/- 0.4 (syst.))*10^{-5}, B(B0->D_s*+pi-)=(2.8 +/- 0.6 (stat.) +/- 0.5 (syst.))*10^{-5}, and B(B0->D_s*-K+)=(2.0 +/- 0.5 (stat.) +/- 0.4 (syst.))*10^{-5}. The significance of the measurements to differ from zero are 5, 9, 6, and 5 standard deviations, respectively.
We report on a study of the decay B0bar -> D*+ omega pi- with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232 million BBbar decays, we measure the branching fraction BF(B0bar -> D*+ omega pi-) = (2.88 +/- 0.21(stat.) +/- 0.31(syst.)) \times 10^{-3}. We study the invariant mass spectrum of the omega pi- system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in tau- -> omega pi- nu_tau. We also measure the polarization of the D*+ as a function of the omega pi- mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D*+ to be Gamma_L/Gamma = 0.654 +/- 0.042(stat.) +/- 0.016(syst.). This is in agreement with the expectations from heavy-quark effective theory and factorization assuming that the decay proceeds as B0bar -> D*+ rho(1450), rho(1450) -> omega pi-.
We present measurements of the B->eta K gamma branching fractions and upper limits for the B->eta' K gamma branching fractions. For B->eta K+ gamma we also measure the time-integrated charge asymmetry. The data sample, collected with the BaBar detector at the Stanford Linear Accelerator Center, represents 232 million produced B B-bar pairs. The results for branching fractions and upper limits at 90% C.L. in units of 10^{-6} are: Br(B0->eta K0 gamma)=11.3+2.8-2.6+/-0.6, Br(B+->eta K+gamma)=10.0+/-1.3+/-0.5, Br(B0->eta' K0 gamma)<6.6, Br(B+->eta' K+ gamma)<4.2. The charge asymmetry in the decay B+->eta K+ gamma is Ach =-0.09+/-0.12+/-0.01. The first errors are statistical and the second systematic.
We report the results of a search for T, CP and CPT violation in B0-B0bar mixing using an inclusive dilepton sample collected by the BaBar experiment at the PEP-II B Factory. Using a sample of 232 million BBbar pairs, with a simultaneous likelihood fit of the same-sign and opposite-sign dileptons, we measure the T and CP violation parameter |q/p|-1 = (-0.8 +/- 2.7(stat.) +/- 1.9(syst.))e-03, and the CPT and CP parameters Im(z) = (-13.9 +/- 7.3 (stat.) +/- 3.2(syst.))e-03 and DeltaGamma x Re(z) = (-7.1 +/- 3.9(stat.) +/- 2.0(syst.))e-03 ps^{-1}. The statistical correlation between the measurements of Im(z) and DeltaGamma x Re(z) is 76%.
We present a measurement of the branching fraction of the decay B0 --> a1(1260)^{+-} pi^{-+} with a1(1260)^{+-} --> pi^{-+} pi^{+-} pi^{+-}. The data sample consists of 218 million B B-bar pairs collected at the Y(4S) resonance and recorded by the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. The analysis is based on unbinned multivariate maximum likelihood fit. The measured branching fraction is: (16.6 +/- 1.9 +/- 1.5) 10^{-6}. The decay mode, observed for the first time, is seen with a significance of 9.2 sigma (systematic uncertainties included).
A search for charmed baryons decaying to $D^0 p$ reveals two states: the $Λ_c(2880)^+$ baryon and a previously unobserved state at a mass of [$2939.8\pm 1.3 \text{(stat.)}\pm 1.0 \text{(syst.)}$]~\mevcc and with an intrinsic width of [$17.5\pm 5.2 \text{(stat.)}\pm 5.9 \text{(syst.)}$]~\mev. Consistent and significant signals are observed for the $K^-π^+$ and $K^-π^+π^-π^+$ decay modes of the $D^0$ in 287 ${\rm fb}^{-1}$ annihilation data recorded by the BaBar detector at a center-of-mass energy of 10.58~${\rm GeV}/c^2$. There is no evidence in the $D^+ p$ spectrum of doubly-charged partners. The mass and intrinsic width of the $Λ_c(2880)^+$ baryon and relative yield of the two baryons are also measured.
We present results of a search for the X(3872) in B0-->X(3872)KS0,X(3872)-->J/psi pi+ pi-, improved measurements of B-->X(3872)K-, and a study of the J/psi pi+ pi- mass region above the X(3872). We use 232x106 B[overline B] pairs collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric-energy storage rings. The results include the 90% confidence interval 1.34x10-6 X(3872)K0,X-->J/psi pi+ pi-)<10.3x10-6 and the branching fraction BR(B-->X(3872)K-,X-->J/psi pi+ pi-)=(10.1+-2.5+-1.0)x10-6. We observe a (2.7+-1.3+-0.2)MeV/c2 mass difference of the X(3872) produced in the two decay modes. Furthermore, we search for the Y(4260) in B decays and set the 95% C.L. upper limit BR(B-->Y(4260)K-,Y(4260)-->J/psi pi+ pi-)<2.9x10-5.
We describe searches for decays to two-body charmless final states eta' eta, eta' pi0 and eta pi0 of B0 mesons produced in e+e- annihilation. The data, collected with the BaBar detector at the Stanford Linear Accelerator Center, represent 232 million produced B-anti-B pairs. The results for branching fractions are, in units of 10^-6 (upper limits at 90% C.L.): BF(B0 -> eta' eta) = 0.2 +0.7 -0.5 +/- 0.4 (<1.7), BF(B0 -> eta pi0) = 0.6 +0.5 -0.4 +/- 0.1 (<1.3), and BF(B0 -> eta' pi0) = 0.8 +0.8 -0.6 +/- 0.1 (<2.1). The first error quoted is statistical and the second systematic.
We present updated results on time-dependent CP asymmetries in fully reconstructed B0->D(*)+-pi-+ and B0->D+-rho-+ decays in approximately 232 million Y(4S)->BBbar events collected with the BaBar detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum likelihood fit we obtain for the parameters related to the CP violation angle 2beta+gamma: a^{Dπ} = -0.010 +/- 0.023 +/- 0.007, c_{\rm lep}^{Dπ} = -0.033 +/- 0.042 +/- 0.012, a^{D^*π} = -0.040 +/- 0.023 +/- 0.010, c_{\rm lep}^{D^*π} = 0.049 +/- 0.042 +/- 0.015, a^{Dρ} = -0.024 +/- 0.031 +/- 0.009, c_{\rm lep}^{Dρ} = -0.098 +/- 0.055 +/- 0.018, where the first error is statistical and the second is systematic. Using other measurements and theoretical assumptions, we interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle and find |sin(2beta+gamma)| > 0.64 (0.40) at 68% (90%) confidence level.
We analyze the decay B0 -> K0s pi+ pi- using a sample of 232 million Upsilon(4S) -> BB decays collected with the BaBar detector at the SLAC PEP-II asymmetric-energy B factory. A maximum likelihood fit finds the following branching fractions: BF(B0 -> K0 pi+ pi-) = (43.0 +/- 2.3 +/- 2.3) x 10^{-6}, BF(B0 -> f0 (-> pi+ pi-) K0) = (5.5 +/- 0.7 +/- 0.5 +/- 0.3) x 10^{-6} and BF(B0 -> K*+ pi-) = (11.0 +/- 1.5 +/- 0.5 +/- 0.5) x 10^{-6}. For these results, the first uncertainty is statistical, the second is systematic, and the third (if present) is due to the effect of interference from other resonances. We also measure the CP-violating charge asymmetry in the decay B0 -> K*+ pi-, A(B0 -> K*+ pi-) = -0.11 +/- 0.14 +/- 0.05.
We present a simultaneous measurement of the B0bar lifetime tau_B0 and B0B0bar oscillation frequency Delta_md. We use a sample of about 50000 partially reconstructed B0bar --> D*+ ell- nu-bar decays identified with the BABAR detector at the PEP-II e+e- storage ring at SLAC. The flavor of the other B meson in the event is determined from the charge of another high-momentum lepton. The results are tau_B0 = (1.504 +/- 0.013 (stat) {+0.018}/{-0.013} (syst)) ps, Delta_md = (0.511 +/- 0.007 (stat) {+0.007}/{-0.006} (syst)) ps-1
We study the two-body decays of B^\pm mesons to K^\pm and a charmonium state, X_{c\bar c}, in a sample of 210.5 fb^{-1} of data from the BaBar experiment. We perform measurements of absolute branching fractions BR(B^\pm --> K^\pm X_{c\bar c}) using a missing mass technique, and report several new or improved results. In particular, the upper limit BR(B^\pm --> K^\pm X(3872))<3.2 10^-4 at 90% CL and the inferred lower limit BR(X(3872) --> J/ψπ^+π^-)>4.2% will help in understanding the nature of the recently discovered X(3872).