arXiv subjects

The BABAR Collaboration

Publications and source records attributed to The BABAR Collaboration.

At least 253 records · Page 14Linked to original sources

arXiv2007

A Measurement of the Branching Fractions of exclusive Bbar -> D(*)(pi)l-nubar Decays in Events with a Fully Reconstructed B Meson

We report a measurement of the branching fractions for Bbar -> D(*)(pi)l-nubar decays based on 341.1 fb-1 of data collected at the Upsilon(4S) resonance with the babar detector at the PEP-II e+e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We obtain B(B- -> D0l-nubar) = (2.33 +/- 0.09(stat.) +/- 0.09(syst.))%, B(B- -> D*0l-nubar) = (5.83 +/- 0.15(stat.) +/- 0.30(syst.))%, B(B0bar -> D+l-nubar) = (2.21 +/- 0.11(stat.) +/- 0.12(syst.))%, B(B0bar -> D*+l-nubar) = (5.49 +/- 0.16(stat.) +/- 0.25(syst.))%, B(B- -> D+pi-l-nubar) = (0.42 +/- 0.06(stat.) +/- 0.03(syst.))%, B(B- -> D*+pi-l-nubar) = (0.59 +/- 0.05(stat.) +/- 0.04(syst.))%, B(B0bar -> D0pi+l-nubar) = (0.43 +/- 0.08(stat.) +/- 0.03(syst.))%, and B(B0bar -> D*0pi+l-nubar) = (0.48 +/- 0.08(stat.) +/- 0.04(syst.))%.

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arXiv2007

Measurement of D0-anti-D0 Mixing using the Ratio of Lifetimes for the Decays D0 --> K-pi+, K-K+, and pi-pi+

We present a measurement of $D^0$-$\bar{D^0}$ mixing parameters using the ratios of lifetimes extracted from a sample of $D^0$ mesons produced through the process $D^{*+}\to\D^0π^+$, that decay to $K^{+}π^{-}$, K^{-}K^{+}$, or $π^-π^+$. The Cabibbo-suppressed modes $K^{-}K^{+}$ and $π^-π^+$ are compared to the Cabibbo-favored mode $K^{+}π^{-}$ to obtain a measurement of $y_{CP}$, which in the limit of CP conservation corresponds to the mixing parameter $y$. The analysis is based on a data sample of 384 $fb^{-1}$ collected by the $BaBar$ detector at the PEP-II asymmetric-energy $e^+e^-$ collider. We obtain $y_{CP} = [1.24\pm 0.39\mathrm{(stat)} \pm 0.13\mathrm{(syst)}]%$, which is evidence of $D^0$-$\bar{D^0}$ mixing at the $3σ$ level, and $ΔY = [-0.26\pm 0.36\mathrm{(stat)} \pm 0.08 \mathrm{(syst)}]%$, where $ΔY$ constrains possible CP violation. Combining this result with a previous $BaBar$ measurement of $y_{CP}$ obtained from a separate sample of $D^0\to K^{-}K^{+}$ events, we obtain $y_{CP} = [1.03\pm 0.33 \mathrm{(stat)} \pm 0.19 \mathrm{(syst)}]%$.

hep-ex↗

arXiv2007

Search for the decay B+ -> K+ tau-/+ mu+/-

We present a search for the lepton flavor violating decay B+ --> K+ tau-/+ mu+/- using 383 million B Bbar events collected by the BABAR experiment. The branching fraction for this decay can be substantially enhanced in new physics models. The kinematics of the tau from the signal B decay are inferred from the K+, mu, and other B in the event, which is fully reconstructed in one of a variety of hadronic decay modes, allowing the signal B candidate to be fully reconstructed. We observe no excess of events over the expected background and set a limit of B(B+ --> K+ tau mu) < 7.7 x 10^-5 at 90% confidence level, where the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+ mu- final states. We use this result to improve a model-independent bound on the energy scale of flavor-changing new physics.

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arXiv2007

Observation of the Decay B+ --> K+K-pi+

We report the observation of charmless hadronic decays of charged B mesons to the final state K+K-pi+. Using a data sample of 347.5 fb^-1 collected at the Y(4S) resonance with the BABAR detector, we observe 429+/-43 signal events with a significance of 9.6 sigma. We measure the inclusive branching fraction BF(B+ --> K+K-pi+) = [5.0+/-0.5(stat)+/-0.5(syst)]x10^-6. Inspection of the Dalitz plot of signal candidates shows a broad structure peaking near 1.5 GeV/c^2 in the K+K- invariant mass distribution. We find the direct CP asymmetry to be consistent with zero.

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arXiv2007

Measurement of the CP-Violating Asymmetries in B0 -> KS pi0 and of the Branching Fraction of B0 -> K0 pi0

We present a measurement of the time-dependent CP-violating asymmetries in $B^0 \to K^0_{\scriptscriptstyle S}π^0$ decays based on 383 million $Υ(4S)\to B\kern 0.18em\bar{\kern -0.18em B}$ events collected by the \mbox{\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} experiment at the PEP-II asymmetric-energy $B$ Factory at SLAC. We measure the direct CP-violating asymmetry $C_{K^0_{\scriptscriptstyle S}π^0} = 0.24 \pm 0.15 \pm 0.03$ and the CP-violating asymmetry in the interference between mixing and decay $S_{K^0_{\scriptscriptstyle S}π^0} = 0.40 \pm 0.23 \pm 0.03$, where the first errors are statistical and the second are systematic. On the same sample, we measure the decay branching fraction, obtaining ${\cal B}(B^0 \to K^0π^0)= (10.3 \pm 0.7 \pm 0.6)\times 10^{-6}$.

hep-ex↗

arXiv2007

Search for CPT and Lorentz Violation in B0-B0bar Oscillations with Dilepton Events

We report results of a search for CPT and Lorentz violation in B0-B0bar oscillations using inclusive dilepton events from 232 million Y(4S) --> BBbar decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8sigma significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities Δ(a_μ) in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26/year to 2.1/day are also compatible with no signal.

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arXiv2007

Study of the Exclusive Initial-State-Radiation Production of the DDbar System

A search for charmonium and other new states is performed in a study of exclusive initial-state-radiation production of D Dbar events from electron-positron annihilations at a center-of-mass energy of 10.58 GeV. The data sample corresponds to an integrated luminosity of 384 fb-1 and was recorded by the BABAR experiment at the PEP-II storage ring. The D Dbar mass spectrum shows clear evidence of the psi(3770) plus other structures near 3.9, 4.1, and 4.4 GeV/c^2. No evidence for Y(4260) -> D Dbar is observed, leading to an upper limit of B(Y(4260) -> D Dbar)/B(Y(4260) -> J/psi pi+ pi-) < 1.0 at 90 % confidence level.

hep-ex↗

arXiv2007

Measurement of CP Asymmetries in B0 --> K0S K0S K0S Decays

We present measurements of the time-dependent CP-violating asymmetries in B0 --> K0S K0S K0S decays based on 384 million Y(4S) decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We obtain the CP asymmetry parameters C = 0.02 +/- 0.21 +/- 0.05 and S = -0.71 +/- 0.24 +/- 0.04, where the first uncertainties are statistical and the second systematic. These results are consistent with standard model expectations.

hep-ex↗

arXiv2007

Study of Resonances in Exclusive B Decays to Dbar()D()K

We present a study of resonances in exclusive decays of $B$ mesons to $\bar{D}^{(*)} D^{(*)} K$. We report the observation of the decays $B \to \Dbar^{(*)} D^+_{s1}(2536)$ where the $D^+_{s1}(2536)$ is reconstructed in the $D^{*0}K^+$ and $D^{*+} K^0_S$ decay channels. We report also the observation of the decays $B \to ψ(3770) K$ where the $ψ(3770)$ decays to $\Dbar^0 D^0$ and $D^- D^+$. In addition, we present the observation of an enhancement for the $\Dbar^{*0} D^0$ invariant mass in the decays $B \to \Dbar^{*0} D^0 K$, at a mass of $(3875.1 {}^{+0.7}_{-0.5} \pm 0.5)$ MeV/$c^2$ with a width of $(3.0 {}^{+1.9}_{-1.4} \pm 0.9)$ MeV (the first errors are statistical and the second are systematic). Branching fractions and spin studies are shown for the three resonances. The results are based on 347 fb$^{-1}$ of data collected with the BaBar detector at the PEP-II $B$ factory.

hep-ex↗

arXiv2007

Search for Lepton Flavor Violating Decays τ^\pm \to l^\pmω(l = e, μ)

We have searched for lepton flavor violating decays of a $τ$ to a lighter-mass charged lepton and an $ω$ vector mesonusing 384.1 $fb^{-}$ of $e^+e^- $ annihilation data collected with the BABAR detector at the Stanford Linear Accelerator Center PEP-II storage ring. No signal is found, and the upper limits on the branching ratios are determined to be ${\cal B}(τ^{\pm} \to \mathrm{e}^{\pm} ω) < 1.1\times10^{-7}$ and ${\cal B}(τ^{\pm} \to μ^{\pm} ω) < 1.0\times10^{-7}$ at 90% confidence level.

hep-ex↗

arXiv2007

Improved Measurement of CP Violation in Neutral B Decays to c cbar s

We present updated measurements of time-dependent CP asymmetries in fully-reconstructed neutral B decays to several CP eigenstates containing a charmonium meson. The measurements use a data sample of (383 +/- 4) x 10^6 Y(4S)-> BBbar decays collected with the BABAR detector at the PEP-II B factory. We determine sin2beta = 0.714 +/- 0.032 (stat) +/- 0.018 (syst) and |lambda| = 0.952 +/- 0.022 (stat) +/- 0.017 (syst).

hep-ex↗

arXiv2007

A Study of Excited Charm-Strange Baryons with Evidence for new Baryons Ξ_c(3055)^+ and Ξ_c(3123)^+

We present a study of excited charm-strange baryon states produced in $e^+e^-$ annihilations at or near a center-of-mass energy of $10.58\mathrm{Ge\kern -0.1em V}$, in a data sample with an integrated luminosity of $384 fb^{-1}$ recorded with the BABAR detector at the PEP-II $e^+e^-$ storage rings at the Stanford Linear Accelerator Center. We study strong decays of charm-strange baryons to $Λ_c^+K^0_{\scriptscriptstyle S}$, $Λ_c^+K^-$, $Λ_c^+K^-π^+$, $Λ_c^+K^0_{\scriptscriptstyle S}π^-$, $Λ_c^+K^0_{\scriptscriptstyle S}π^-π^+$, and $Λ_c^+K^-π^+π^-$. This study confirms the existence of the states $Ξ_c(2980)^+$, $Ξ_c(3077)^+$, and $Ξ_c(3077)^0$, with a more accurate determination of the $Ξ_c(2980)^+$ mass and width. We also present evidence for two new states, $Ξ_c(3055)^+$ and $Ξ_c(3123)^+$, decaying through the intermediate resonant modes $Σ_c(2455)^{++}K^-$ and $Σ_c(2520)^{++}K^-$, respectively. For each of these baryons, we measure the yield in each final state, determine the statistical significance, and calculate the product of the production cross-section and branching fractions. We also measure the masses and widths of these excited charm-strange baryons.

hep-ex↗

arXiv2007

A study of Bbar -> Xi_c Lambda_c^- and Bbar -> Lambda_c^+ Lambda_c^- Kbar decays at BABAR

We report measurements of B-meson decays into two- and three-body final states containing two charmed baryons using a sample of 230 million Y(4S) -> B Bbar decays. We find significant signals in two modes, measuring branching fractions BF(B^- -> Λ_c^+ Λ_c^- K^-) = (1.14 +- 0.15 +- 0.17 +- 0.60) x 10^{-3} and BF(B^- -> Ξ_c^0 Λ_c^-) x BF(Ξ_c^0 -> Ξ^- π^+) = (2.08 +- 0.65 +- 0.29 +- 0.54) x 10^{-5}, where the uncertainties are statistical, systematic, and from the branching fraction BF(Λ_c^+ -> p K^- π^+), respectively. We also set upper limits at the 90% confidence level on two other modes: BF(B0bar -> Ξ_c^+ Λ_c^-) x BF(Ξ_c^+ -> Ξ^- π^+ π^+) < 5.6 x 10^{-5} and BF(B0bar -> Λ_c^+ Λ_c^- K0bar) < 1.5 x 10^{-3}. We observe structure centered at an invariant mass of 2.93 GeV/c^2 in the Λ_c^+ K^- mass distribution of the decay B^- -> Λ_c^+ Λ_c^- K^-.

hep-ex↗

arXiv2007

Measurements of CP-Violating Asymmetries in the Decay B0-->K+K-K0

We analyze the decay B0 --> K+ K- K0 using 383 million B-Bbar events collected by the BaBar detector at SLAC to extract CP violation parameter values over the Dalitz plot. Combining all K+ K- K0 events, we find A_CP = -0.015 +/- 0.077 +/- 0.053 and beta_eff = 0.352 +/- 0.076 +/- 0.026 rad, corresponding to a CP violation significance of 4.8 sigma. A second solution near pi/2 - beta_eff is disfavored with a significance of 4.5 sigma. We also report A_CP and beta_eff separately for decays to phi(1020) K0, f0(980) K0, and K+ K- K0 with m_{K+ K-} > 1.1 GeV/c^2.

hep-ex↗

arXiv2007

Observation of B^+ Meson Decays to a1(1260)^+ K^0 and B^0 to a1(1260)^- K^+

We present branching fraction measurements of the decays B^{+} -> a1(1260)^{+} K^{0} and B^{0} to a1(1260)^{-} K^{+} with a1(1260)^{+} -> pi^{-} pi^{+} pi^{+}. The data sample corresponds to 383 million B B-bar pairs produced in e^{+}e^{-} annihilation through the Y(4S) resonance. We measure the products of the branching fractions: B(B^{+}-> a1(1260)^{+} K^{0})B(a1(1260)^{+} -> pi^{-} pi^{+} pi^{+}) = (17.4 +/- 2.5 +/- 2.2) 10^{-6} B(B^{0}-> a1(1260)^{-} K^{+})B(a1(1260)^{-} -> pi^{+} pi^{-} pi^{-}) = (8.2 +/- 1.5 +/- 1.2) 10^{-6}. We also measure the charge asymmetries A_{ch}(B^{+} -> a1(1260)^{+} K^{0})= 0.12 +/- 0.11 +/- 0.02 and A_{ch}(B^{0} -> a1(1260)^{-} K^{+})= -0.16 +/- 0.12 +/- 0.01. The first uncertainty quoted is statistical and the second is systematic.

hep-ex↗

arXiv2007

Study of e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 using Initial State Radiation with BABAR

We study the e+e- --> Lambda anti-Lambda gamma, Lambda anti-Sigma0 gamma, Sigma0 anti-Sigma0 gamma processes using 230 fb-1 of integrated luminosity collected by the BABAR detector at e+e- center-of-mass energy of 10.58 GeV. From the analysis of the baryon-antibaryon mass spectra the cross sections for e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 are measured in the dibaryon mass range from threshold up to 3 GeV/c^2. The ratio of electric and magnetic form factors, |G_E/G_M|, is measured for e+e- --> Lambda anti-Lambda, and limits on the relative phase between Lambda form factors are obtained. We also measure the J/psi --> Lambda anti-Lambda, Sigma0 anti-Sigma0 and psi(2S) --> Lambda anti-Lambda branching fractions.

hep-ex↗

arXiv2007

Observation of the Semileptonic Decays B --> D* tau nubar and Evidence for B --> D tau nubar

We present measurements of the semileptonic decays B- --> D0 tau- nubar, B- --> D*0 tau- nubar, B0bar --> D+ tau- nubar, and B0bar --> D*+ tau- nubar, which are potentially sensitive to non--Standard Model amplitudes. The data sample comprises 232x10^6 Upsilon(4S) --> BBbar decays collected with the BaBar detector. From a combined fit to B- and B0bar channels, we obtain the branching fractions B(B --> D tau- nubar) = (0.86 +/- 0.24 +/- 0.11 +/- 0.06)% and B(B --> D* tau- nubar) = (1.62 +/- 0.31 +/- 0.10 +/- 0.05)% (normalized for the B0bar), where the uncertainties are statistical, systematic, and normalization-mode-related.

hep-ex↗

arXiv2007

Branching fraction and CP-violation charge asymmetry measurements for B-meson decays to eta K+-, etapi+-, eta'K, eta'pi+-, omega K, and omegapi+-

We present measurements of the branching fractions for B0 meson decays to eta'K0 and omegaK0, and of the branching fractions and CP-violation charge asymmetries for B+ meson decays to etapi+, etaK+, eta'pi+, eta'K+, omegapi+, and omegaK+. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 383 million BBbar pairs produced in e+e- annihilation. The measurements agree with previous results; we find no evidence for direct CP violation.

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