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The BABAR Collaboration

Publications and source records attributed to The BABAR Collaboration.

At least 397 records · Page 22Linked to original sources

arXiv2006

Measurement of the eta and etaprime transition form factors at q^2=112 GeV^2

We report a study of the processes e+e- -> eta gamma and e+e- -> etaprime gamma at a center-of-mass energy of 10.58 GeV, using a 232 fb^-1 data sample collected with the BABAR detector at the PEP-II collider at SLAC. We observe 20+6-5 eta gamma and 50+8-7 etaprime gamma events over small backgrounds, and measure the cross sections sigma(e+e- -> eta gamma) =4.5+1.2-1.1(stat)+-0.3(sys) fb and sigma(e+e- -> etaprime gamma)=5.4+-0.8(stat)+-0.3(sys) fb. The corresponding transition form factors at q^2 = 112 GeV^2 are q^2|F_eta(q^2)|=0.229+-0.030+-0.008 GeV, and q^2|F_etaprime(q^2)|=0.251+-0.019+-0.008 GeV, respectively.

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arXiv2006

B Meson Decays to mega K*, omega rho, omega omega, omega phi, and omega f0

We describe searches for B meson decays to the charmless vector-vector final states omega K*, omega rho, omega omega, and omega phi with 233 times 10^{6} BB pairs produced in e+e- annihilation at sqrt{s}=10.58 GeV. We also search for the vector-scalar B decay to omega f_0. We measure the following branching fractions in units of 10^{-6}: BR(B0 --> omega K*0) = 2.4 +/- 1.1 +/- 0.7 (<4.2), BR(B+ --> omega K*+) = 0.6 {+1.4}_{-1.2} {+1.1}_{-0.9} (<3.4), BR(B0 --> omega rho0) = -0.6 +/- 0.7 {+0.8}_{-0.3} (<1.5), BR(B+ --> omega rho+) = 10.6 +/- 2.1 {+1.6}_{-1.0}, BR(B0 --> omega omega) = 1.8 {+1.3}_{-0.9} +/- 0.4 (<4.0), BR(B0 --> omega phi) = 0.1 +/- 0.5 +/- 0.1 (<1.2), and BR(B0 --> omega f_0) = 0.9 +/- 0.4 {+0.2}_{-0.1} (<1.5). In each case the first error quoted is statistical, the second systematic, and the upper limits are defined at the 90% confidence level. For B+ --> omega rho+ decays we also measure the longitudinal spin component f_L=0.82 +/- 0.11 +/- 0.02 and the charge asymmetry A_CP=0.04 +/- 0.18 +/- 0.02.

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arXiv2006

Dalitz plot analysis of the decay B+- -> K+-K+-K-+

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.

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arXiv2006

Observation of $Υ(4S) decays to $π^+pi^-Υ(1S)$ and $π^+pi^-Υ(2S)

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.

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arXiv2006

Measurement of B0bar -> D()0 K()0bar Branching Fractions

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.

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arXiv2006

Search for the Decay tau- --> 3pi- 2pi+ 2pi0 nu_tau

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.

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arXiv2006

Observation of Decays B0->D_s()+pi- and B0->D_s()-K+

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.

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arXiv2006

Study of the decay B0bar -> D*+ omega pi-

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-.

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arXiv2006

Measurement of Branching Fractions in Radiative B Decays to eta K gamma and Search for B Decays to eta' K gamma

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.

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arXiv2006

Search for T, CP and CPT Violation in B0-B0bar Mixing with Inclusive Dilepton Events

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%.

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arXiv2006

Observation of B0 Meson Decay to a1(1260)+- pi-+

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).

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arXiv2006

Observation of a Charmed Baryon Decaying to D0 p at a Mass Near 2.94 GeV/c2

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.

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arXiv2006

Branching Fraction Limits for B0 Decays to eta' eta, eta' pi0 and eta pi0

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.

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arXiv2006

Measurement of time-dependent CP asymmetries in B0->D(*)+-pi-+ and B0->D+-rho-+ decays

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.

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arXiv2006

Measurements of Neutral B Decay Branching Fractions to K0S pi+ pi- Final States and the Charge Asymmetry of B0 --> K*+ pi-

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.

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arXiv2006

Measurement of the B0bar Lifetime and the B0B0bar Oscillation Frequency Using Partially Reconstructed B0bar --> D*+ ell- nu-bar Decays

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

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arXiv2006

Measurements of the Absolute Branching Fractions of B^\pm --> K^\pm X_{c\bar c}

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).

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arXiv2006

A Search for the Decay B+ --> tau+ nu_tau

We search for the rare leptonic decay B+ --> tau+ nu_tau in a sample of 232x10^6 BBbar pairs collected with the BABAR detector at the SLAC PEP-II B-Factory. Signal events are selected by examining the properties of the B meson recoiling against the semileptonic decay B- --> D*0 l- nu_lbar. We find no evidence for a signal and set an upper limit on the branching fraction of BR(B+ --> tau+ nu_tau) < 2.8x10^{-4} at the 90% confidence level. We combine this result with a previous, statistically independent BABAR search for B+ --> tau+ nu_tau to give an upper limit of BR(B+ --> tau+ nu_tau) < 2.6x10^{-4} at the 90% confidence level.

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