arXiv subjects

The BABAR Collaboration

Publications and source records attributed to The BABAR Collaboration.

At least 433 records · Page 24Linked to original sources

arXiv2005

Measurements of the rare decays B -> Kl+l- and B -> K*l+l-

We present measurements of the flavor-changing neutral current decays B -> Kl+l- and B -> K*l+l-, where l+l- is either an e+e- or mu+mu- pair. The data sample comprises 229 X 10^6 Y(4S) -> BBbar decays collected with the BaBar detector at the PEP-II e+e- storage ring. We measure the branching fractions BF(B -> Kl+l-) = (0.34 +- 0.07 +- 0.03) X 10^-6 and BF(B -> K*l+l-) = (0.78^{+0.19}_{-0.17} +/- 0.12) X 10^-6, the direct CP asymmetries of these decays, and the relative abundances of decays to electrons and muons.

hep-ex↗

arXiv2005

A Precision Measurement of the Lambda_c Baryon Mass

The $Λ_c^+$ baryon mass is measured using $Λ_c^+\toΛK^0_S K^+$ and $Λ_c^+\toΣ^0 K^0_S K^+$ decays reconstructed in 232 fb$^{-1}$ of data collected with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ storage ring. The $Λ_c^+$ mass is measured to be $2286.46\pm0.14\mathrm{MeV}/c^2$. The dominant systematic uncertainties arise from the amount of material in the tracking volume and from the magnetic field strength.

hep-ex↗

arXiv2005

Measurement of the B+- --> rho+- pi0 Branching Fraction and Direct CP Asymmetry

An improved measurement of the process B+- --> rho+- pi0 is presented. The data sample of 211/fb comprises 232 million Y(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. The yield and CP asymmetry are calculated using an extended maximum likelihood fitting method. The branching fraction and asymmetry are found to be BR(B+- --> rho+- pi0) = [10.0 +- 1.4 (stat) +- 0.9 (syst)]x 10^-6 and Acp(B+- --> rho+- pi0) = -0.01 +- 0.13 (stat) +- 0.02 (syst), superseding previous measurements. The statistical significance of the branching fraction is calculated to be 8.7sigma.

hep-ex↗

arXiv2005

Evidence for the Decay B+- --> K*+- pi0

We have measured the process B+- --> (K*+- --> K+- pi0) pi0 based on 232 million Y(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. From a signal yield of 89 +- 26 events we obtain the branching fraction BR(B+- --> K*+- pi0)=[6.9 +- 2.0 (stat) +- 1.3 (syst)] x10^-6 with a statistical significance of 3.6 standard deviations including systematic uncertainties, and a charge asymmetry of 0.04 +- 0.29 (stat) +- 0.05 (syst).

hep-ex↗

arXiv2005

Search for Lepton Flavor Violation in the Decay tau -> mu gamma

A search for the nonconservation of lepton flavor number in the decay tau -> mu gamma has been performed using 2.07 x 10^8 e+e- -> tau+ tau- events produced at a center-of-mass energy near 10.58 GeV with the BABAR detector at the PEP-II storage ring. We find no evidence for a signal and set an upper limit on the branching ratio of BR(tau -> mu gamma) < 6.8 x 10^-8 at 90% confidence level.

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arXiv2005

Measurement of Time-Dependent CP Asymmetries in B0 -> D(*)D Decays

We present a first measurement of CP asymmetries in neutral B decays to D+D-, and updated CP asymmetry measurements in decays to D*+D- and D*-D+. We use fully-reconstructed decays collected in a data sample of (232 +- 3) x 10^6 Y(4S) -> BBbar events in the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We determine the time-dependent asymmetry parameters to be S_{D*+D-} = -0.54 +- 0.35 +- 0.07, C_{D*+D-} = 0.09 +- 0.25 +- 0.06, S_{D*-D+} = -0.29 +- 0.33 +- 0.07, C_{D*-D+} = 0.17 +- 0.24 +- 0.04, S_{D+D-} = -0.29 +- 0.63 +- 0.06, and C_{D+D-} = 0.11 +- 0.35 +- 0.06, where in each case the first error is statistical and the second error is systematic.

hep-ex↗

arXiv2005

Measurement of the branching fraction and decay rate asymmetry of B- --> D_{pi+pi-pi0}K-

We report the observation of the decay $B^- \to D_{π^+π^-π^0} K^-$, where $D_{π^+π^-π^0}$ indicates a neutral $D$ meson detected in the final state $π^+π^-π^0$, excluding $K_S π^0$. This doubly Cabibbo-suppressed decay chain can be used to measure the CKM phase $γ$. Using about 229 million $e^+e^- \to B \bar B$ events recorded by the BaBar experiment at the PEP-II $e^+e^-$ storage ring, we measure the branching fraction ${\cal B}(B^- \to D_{π^+π^-π^0} K^-) = (5.5 \pm 1.0 {\rm(stat.)} \pm 0.7 {\rm(syst.)})\times 10^{-6}$ and the decay rate asymmetry $A = 0.02 \pm 0.16 {\rm(stat.)} \pm 0.03 {\rm(syst.)}$ for the full decay chain.

hep-ex↗

arXiv2005

Measurement of CP Asymmetries in B0 --> Phi K0 and B0 --> K+K-K0S Decays

We measure the time-dependent CP asymmetry parameters in B0 --> K+ K- K0 based on a data sample of approximately 227 million B-meson pairs recorded at the Upsilon(4S) resonance with the BaBar detector at the PEP-II B-meson Factory at SLAC. We reconstruct two-body B0 decays to Phi(1020) K0S and Phi(1020)K0L, and the three-body decay K+ K- K0S with Phi(1020) K0S excluded. For the B0 --> Phi K0 decays, we measure sin(2 beta_{eff})(Phi K0) = +0.50 +/- 0.25(stat) +0.07/-0.04(syst). The B0 --> K+ K- K0S decays are dominated by K+ K- S-wave, as determined from an angular analysis; we measure sin(2 beta_{eff})(K+ K- K0S) = +0.55 +/- 0.22(stat) +/- 0.04(syst) +/- 0.11(CP), where the last error is due to the uncertainty in the fraction of CP-even contributions to the decay amplitude. We find no evidence for direct CP violation.

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arXiv2005

Measurement of Time-Dependent CP-Violating Asymmetries and Constraints on sin(2 beta+gamma) with Partial Reconstruction of B->D*-+pi+- Decays

We present a measurement of the time-dependent CP-violating asymmetries in decays of neutral B mesons to the final states D*-+ pi+-, using approximately 232 million BBbar events recorded by the BABAR experiment at the PEP2 e+e- storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum pi+- from the B decay and the low-momentum pi-+ from the D*-+ decay are used. % We measure the parameters related to 2beta+gamma to be a_D*pi=-0.034 +- 0.014 +- 0.009 and c_l_D*pi = -0.019 +- 0.022 +- 0.013. With some theoretical assumptions, we interpret our results in term of the lower limits |\sin(2beta+gamma)|> 0.62 (0.35) at 68% (90%) confidence level.

hep-ex↗

arXiv2005

B^0 --> K^+ π^- π^0 Dalitz Plot Analysis

We present preliminary results on the Dalitz plot analysis of $B^0 \to K^+ π^- π^0$ decays. The data sample comprises 213 million $Υ(4S) \to B {\bar B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We report measurements of the inclusive branching fraction, quasi-two-body fractions and CP-violating charge asymmetries for intermediate states including $K^*(892)^+ π^-$ and $ρ(770)^- K^+$. Observations of $B^0$ decays to the $Kπ$ $S$-wave intermediate states, $K_0^*(1430)^+ π^-$ and $K_0^*(1430)^0 π^0$, are reported. Evidence of the decay $B^0 \to K^*(892)^0 π^0$ is seen. We set upper limits at 90% confidence level on branching fractions of the nonresonant and other less significant intermediate states.

hep-ex↗

arXiv2005

Measurement of branching fractions and charge asymmetries in B+ decays to etapi+, etaK+, etarho+ and eta'pi+, and search for B0 decays to etaK0 and etaomega

We present measurements of branching fractions and charge asymmetries for six B-meson decay modes with an eta or eta' meson in the final state. The data sample corresponds to 232 million BBbar pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- B Factory at SLAC. We measure the branching fractions (in units of 10^-6): B(B->etapi+)=5.1+/-0.6+/-0.3, B(B->etaK+)=3.3+/-0.6+/-0.3, B(B->etaK0)=1.5+/-0.7+/-0.1 (<2.5 at 90% C.L.), B(B->etarho+)=8.4+/-1.9+/-1.1, B(B->etaomega)=1.0+/-0.5+/-0.2 (<1.9 at 90% C.L.), and B(B->eta'pi+)=4.0+/-0.8+/-0.4, where the first uncertainty is statistical and second systematic. We also determine the charge asymmetries for the charged modes: Ach(B->etapi+)=-0.13+/-0.12+/-0.01, Ach(B->etaK+)=-0.20+/-0.15+/-0.01, Ach(B->etarho+)=0.02+/-0.18+/-0.02, and Ach(B->eta'pi+)=0.14+/-0.16+/-0.01.

hep-ex↗

arXiv2005

Measurement of the Ratio BR(B- --> D0 K-)/BR(B- --> D0 pi-) and of the CP Asymmetry of B- --> D*0(CP+) K- Decays

We study the decays B- --> D*0 pi- and B- --> D*0 K-, where the D*0 decays into D0 pi0, with the D0 reconstructed in the CP-even (CP+) eigenstates K- K+ and pi- pi+ and in the (non-CP) channels K- pi+, K- pi+ pi+ pi-, and K- pi+ pi0. Using a sample of about 123 million BBbar pairs, we measure the ratios of decay rates R*(non-CP)=BR(B- --> D*0(non-CP) K-)/BR(B- --> D*0(non-CP) pi-) = 0.0813+-0.0040(stat)+0.0042-0.0031}(syst), and provide the first measurements of R*(CP+)= BR(B- --> D*0(CP+) K-)/BR(B- --> D*0(CP+) pi-) = 0.086+-0.021(stat)+-0. 007(syst), and of the CP asymmetry A*(CP+) = (BR(B- --> D*0(CP+) K-) - BR(B+ --> D*0(CP+) K+))/(BR(B- --> D*0(CP+) K-) + BR(B+ --> D*0(CP+) K+)) = -0.10+-0.23(stat)+0.03-0.04(syst).

hep-ex↗

arXiv2005

Measurement of Branching Fraction and CP-Violating Asymmetry for B->omegaKs

We present a preliminary measurement of the branching fraction and CP-violating parameters S and C for the decay B->omegaKs. The data sample corresponds to 232x10^6 BBbar pairs produced from e+e- annihilation at the Upsilon(4S) resonance. We measure B(omegaK0)=(5.9+/-1.0+/-0.4)x10^-6, S=0.50+0.34-0.38+/-0.02 and C=-0.56+0.29-0.27+/-0.03.

hep-ex↗

arXiv2005

Measurement of the Branching Fraction and the CP-Violating Asymmetry for the Decay B0 --> K0S Pi0

We measure the branching fraction and the CP-violating asymmetry of $B^{0}\to K_{s}^{0}π^{0}$ decays with 227 million $Υ(4S)\to B\bar{B}$ events collected with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC. We obtain a branching fraction ${\cal B}(B^{0}\to K^{0}π^{0}) = (11.4 \pm 0.9 \pm 0.6) \times 10^{-6}$ and CP-violating asymmetry parameters $C_{K_{s}^{0}π^{0}} = 0.06 \pm 0.18 \pm 0.03$ and $S_{K_{s}^{0}π^{0}} = 0.35^{+0.30}_{-0.33} \pm 0.04$, where the first error is statistical and the second systematic.

hep-ex↗

arXiv2005

Branching Fraction and CP Asymmetries of $B^0 \to K^0_S K^0_S K^0_S$

We present measurements of the branching fraction and time-dependent CP-violating asymmetries in $B^0 \to K^0_s K^0_s K^0_s$ decays based on 227 million $Υ(4S) \to B \bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We obtain a branching fraction of $(6.9^{+0.9}_{-0.8}\pm 0.6)\times 10^{-6},$ and CP asymmetries $C = -0.34^{+0.28}_{-0.25} \pm 0.05$ and $S = -0.71^{+0.38}_{-0.32} \pm 0.04,$ where the first uncertainties are statistical and the second systematic.

hep-ex↗

arXiv2005

Search for Strange-Pentaquark Production in e+e- Annihilation at sqrt(s)=10.58 GeV

We search for strange pentaquark states that have been previously reported by other experiments -- the $Θ(1540)^+$, $Ξ_5(1860)^{--}$, and $Ξ_5(1860)^0$ -- in 123 fb$^{-1}$ of data recorded with the BaBar detector at the PEP-II $e^+e^-$ storage ring. We find no evidence for these states and set 95% confidence level upper limits on the number of $Θ(1540)^+$ and $Ξ_5(1860)^{--}$ pentaquarks produced per $e^+e^-$ annihilation event that are about eight and four times lower than the rates measured for ordinary baryons of similar mass.

hep-ex↗

arXiv2005

Search for Factorization-Suppressed B -> chi_c K(*) Decays

We search for the factorization-suppressed decays B -> chi_c0 K(*) and B -> chi_c2 K(*), with chi_c0 and chi_c2 decaying into J/psi gamma using a sample of 124 10^6 BBbar events collected with the BABAR detector at the PEP-II storage ring of the Stanford Linear Accelerator Center.

hep-ex↗

arXiv2005

Study of b --> ulnu Decays on the Recoil of Fully Reconstructed B Mesons and Determination of Vub

Based on 88 million Y(4S)->BB decays collected by the BaBar experiment at the PEP-II asymmetric-energy B factory at SLAC, we report preliminary results of four analyses which study in semileptonic charmless B decays, B->Xulnu and measure Vub. In events in which one B meson decay to a hadronic final state is fully reconstructed, the semileptonic decay of the second B meson is identified by the detection of a charged lepton. From both the spectrum of the mass of the hadronic system (mX) and the two-dimensional distribution of mX and q^2 we derive the charmless semileptonic branching fraction and we extract Vub=(4.77\pm 0.28(stat.)\pm 0.25 (sys.)^{+0.65}_{-0.39}(theo.)) 10^-3 and Vub=(4.92\pm 0.39(stat.)\pm 0.36 (sys.)\pm 0.46(theo.)) 10^-3, respectively. We use the same sample to extract the true mX distribution for B->Xulnu events. Finally, we identify several exclusive charmless semileptonic B decays, and measure the branching fractions BR(B->pilnu) = (1.08 \pm 0.28(stat.) \pm 0.16(sys.))10^-4 and BR(B-> rho lnu) = (2.57 \pm 0.52(stat.) \pm 0.59(sys.)) 10^-4 using isospin and quark model constraints. We also set limits on BR(B^- -> eta l nu), BR(B^- -> eta' l nu), $BR(B^- -> a^0_0 l nu), and $BR(B^0 -> a^+_0lnu).

hep-ex↗