arXiv subjects

B. Aubert

Publications and source records attributed to B. Aubert.

At least 235 records · Page 13Linked to original sources

arXiv2006

Measurement of CP-Violating Asymmetries in $B^0\to(ρπ)^0$ Using a Time-Dependent Dalitz Plot Analysis

We report a measurement of CP-violating asymmetries in $B^0\to(ρπ)^0\toπ^+π^-π^0$ decays using a time-dependent Dalitz plot analysis. The results are obtained from a data sample of 347 million $Υ(4S) \to B\bar{B}$ decays, collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure 26 coefficients of the bilinear form factor terms occurring in the time-dependent decay rate of the \Bz meson and derive the physically relevant quantities from these coefficients. In particular we find a three standard deviation evidence of direct CP-violation in $B^0\toρ^\pmπ^\mp$ decays, with systematic uncertainties included. We also achieve a constraint of the angle $α$ of the Unitarity Triangle. All results presented are preliminary.

hep-ex↗

arXiv2006

Measurement of the Absolute Branching Fractions B to Dpi, D*pi, D**pi with a Missing Mass Method

We present branching fraction measurements of charged and neutral B decays to Dpi-, D*pi- and D**pi- with a missing mass method, based on a sample of 231 million Y(4S)-->BBar pairs collected by the BaBar detector at the PEP-II e+e- collider. One of the B mesons is fully reconstructed and the other one decays to a reconstructed charged pion and a companion charmed meson identified by its recoil mass, inferred by kinematics. Here D** refers to the sum of all the non-strange charm meson states with masses in the range 2.2-2.8 Gev/c2.

hep-ex↗

arXiv2006

Branching Fraction Measurements of Charged B Decays to K+K+K-, K+pi+K-, K+K+pi- and K+pi+pi- Final States

Branching fraction and asymmetry measurements of charmless $B^+\to K^{*+}h^+_1h^-_2$ (where $h_{1,2}$ = $K$, $π$) decays are presented, using a data sample of 232 million $Υ(4S) \to$ $BB$ decays collected with the BaBar detector at the SLAC PEP-II asymmetric-energy $B$ factory. Using a maximum likelihood fit, the following branching fraction results were obtained: ${\cal B}$($B^+ \to K^{*+}K^+ K^-)$ = (36.2 $\pm$ 3.3 $\pm$ 3.6) $\times$ 10$^{-6}$ and ${\cal B}$($B^+$ $\to$ $K^{*+}π^+π^-$) = (75.3 $\pm$ 6.0 $\pm$ 8.1) $\times$ 10$^{-6}$. Upper limits were set for ${\cal B}$($B^+$ $\to$ $K^{*+}π^+ K^-$) $<$ 11.8 $\times$ 10$^{-6}$ and ${\cal B}$($B^+$ $\to$ $K^{*+}K^+ π^-$) $<$ 6.1 $\times$ 10$^{-6}$ at 90% confidence level. The charge asymmetries for the decays $B^+ \to K^{*+}K^+ K^-$ and $B^+$ $\to$ $K^{*+}π^+π^-$ were measured to be ${\cal A}_{K^*KK} = 0.11 \pm 0.08 \pm 0.03$ and ${\cal A}_{K^*ππ} = 0.07 \pm 0.07 \pm 0.04$, respectively. The first error quoted on branching fraction and asymmetry measurements is statistical and the second systematic.

hep-ex↗

arXiv2006

Measurement of CP Asymmetries and Branching Fractions in B -> pi pi and B -> K pi decays

We present preliminary measurements of the CP asymmetries and branching fractions for B -> pi pi and B -> K pi decays. A total of 347 million BBbar events collected by the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC are used for these results. We find Spipi = -0.53 +- 0.14 +-0.02, Cpipi = -0.16 +- 0.11 +- 0.03, AKpi = -0.108 +- 0.024 +- 0.008, BF(B0 -> pi0 pi0) = (1.48 +- 0.26 +- 0.12) x 10^-6, BF(B+ -> pi+pi0) = (5.12 +- 0.47 +- 0.29) x 10^-6, BF(B+ -> K+pi0) = (13.3 +- 0.56 +- 0.64) x 10^-6, Cpi0pi0 = -0.33 +- 0.36 +- 0.08, Apipi0 = -0.019 +- 0.088 +- 0.014, AKpi0 = 0.016 +- 0.041 +- 0.012. The measured values of Spipi and Cpipi imply that CP conservation in B0 -> pi+ pi- decays is excluded at the 3.6 sigma level. From these results we present bounds on the CKM angle alpha.

hep-ex↗

arXiv2006

A Study of the DsJ(2317) and DsJ(2460) Mesons in Inclusive ccbar Production Near sqrt(s) = 10.6 GeV

A study of the $D_{sJ}^*(2317)^+$ and $D_{sJ}(2460)^+$ mesons in inclusive $c\bar{c}$ production is presented using 232 ${\rm fb}^{-1}$ of data collected by the BaBar experiment near $\sqrt{s} = 10.6$ \gev. Final states consisting of a $D_s^+$ meson along with one or more $π^0$, $π^\pm$, or $γ$ particles are considered. Estimates of the mass and limits on the width are provided for both mesons and for the $D_{s1}(2536)^+$ meson. A search is also performed for neutral and doubly-charged partners of the $D_{sJ}^*(2317)^+$ meson.

hep-ex↗

arXiv2006

Measurement of the CP Asymmetry and Branching Fraction of B^0 to rho^0 K^0

We present a measurement of the branching fraction and time-dependent CP asymmetry of B^0 to rho^0 K^0. The results are obtained from a data sample of 227 10^6 Y4S to BB_ decays collected with the BaBar detector at the PEP2 asymmetric-energy B Factory at SLAC. From a time-dependent maximum likelihood fit yielding 111+/-19 signal events we find B(B^0 to rho^0 K^0)=(4.9+/-0.8+/-0.9) 10^-6, where the first error is statistical and the second systematic. We report the measurement of the CP parameters S=0.20+/-0.52+/-0.24 and C=0.64+/-0.41+/-0.20.

hep-ex↗

arXiv2006

Study of B --> D^()D_s(J)^() Decays and Measurement of D_s^- and D_sJ(2 460)^- Branching Fractions

We present branching fraction measurements of twelve B meson decays of the form B --> D^(*)D_s(J)^(*). The results are based on Y(4S) decays in BBbar pairs. One of the B mesons is fully reconstructed and the other decays to two charm mesons, of which one is reconstructed, and the mass and momentum of the other is inferred by kinematics. Combining these results with previous exclusive branching fraction measurements, we determine BR(D_s^- --> phi pi^-) = (4.62 +/- 0.36_stat. +/- 0.51_syst.)%, BR(D_sJ(2460)^- --> D_s^*- pi^0) = (56 +/- 13_stat. +/- 9_syst.)% and BR(D-sJ(2460)^- --> D_s^- gamma) = (16 +/- 4_stat. +/- 3_syst.)%.

hep-ex↗

arXiv2006

Search for the decay B0 --> K0_S K0_S K0_L

We present the first search for the decay B0 --> K0_S K0_S K0_L using a data sample of 232 million B Bbar pairs. We find no statistically significant evidence for the non-resonant component of this decay. Our central value for the branching fraction, assuming the true Dalitz distribution is uniform and excluding the phi resonance, is B(B0 --> K0_S K0_S K0_L) = (2.4 +2.7 -2.5 +/- 0.6) x 10^{-6} where the errors are statistical and systematic, respectively. We set a single-sided Bayesian upper limit of B(B0 --> K0_S K0_S K0_L) < 7.4 x 10^{-6} at 90% confidence level using a uniform prior probability for physical values. Assuming the worst-case true Dalitz distribution, where the signal is entirely in the region of lowest efficiency, the 90% confidence level upper limit is B(B0 --> K0_S K0_S K0_L) < 16 x 10^{-6}.

hep-ex↗

arXiv2006

Measurements of CP-Violating Asymmetries and Branching Fractions in B Decays to omegaK and omegapi

We present measurements of CP-violating asymmetries and branching fractions for the decays omegapi+, omegaK+, and omegaK0. The data sample corresponds to 232 million BBbar pairs produced by e+e- annihilation at the Upsilon(4S) resonance. For the decay omegaKs, we measure the time-dependent CP-violation parameters S=0.51+0.35-0.39+/-0.02, and C=-0.55+0.28-0.26+/-0.03. We also measure the branching fractions, in units of 10^-6, B(omegapi+)=6.1+/-0.7+/-0.4, B(omegaK+)=6.1+/-0.6+/-0.4, and B(omegaK0)=6.2+/-1.0+/-0.4, and charge asymmetries Ach(omegapi+)=-0.01+/-0.10+/-0.01 and Ach(omegaK+)=0.05+/-0.09+/-0.01.

hep-ex↗

arXiv2006

A Search for B+ --> tau+ nu Recoiling Against B- --> D0 l- nubar X

We present a search for the decay $B^{+} \to τ^{+} ν_τ$ using 288 fb-1 of data collected at the $Υ(4S)$ resonance with the BaBar detector at the SLAC PEP-II $B$-Factory. A sample of events with one reconstructed semileptonic B decay is selected, and in the recoil a search for $B^{+} \to τ^{+} ν_τ$ signal is performed. The $τ$ is identified in the following channels: {τ^+ \to e^+ ν_e \nutb}, {τ^+ \to μ^+ ν_μ \nutb}, {τ^+ \to π^+ \nutb} and {τ^+ \to π^+ π^0 \nutb}. We measure a branching fraction of $\mathcal{B}(B^{+} \to τ^{+} ν_τ)=(0.88^{+0.68}_{-0.67}({stat.}) \pm 0.11 ({syst.})) \times 10^{-4}$ and extract an upper limit on the branching fraction, at the 90% confidence level, of $\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 1.8 \times 10^{-4}$. We calculate the product of the $B$ meson decay constant and $|\Vub|$ to be $f_{B}\cdot|\Vub| = (7.0^{+2.3}_{-3.6}({stat.})^{+0.4}_{-0.5}({syst.}))\times10^{-4}$ GeV \.

hep-ex↗

arXiv2006

Precise Branching Ratio Measurements of the Decays D0-->pi- pi+ pi0 and D0-->K- K+ pi0

Using 232 fb-1 of e+e- collision data recorded by the BaBar experiment, we measure the ratios of three-body Cabibbo-suppressed decay rates of the D^0 meson relative to that of the Cabibbo-favored decay: B(D0 --> pi- pi+ pi0)/ B(D0 --> K- pi+ pi0) = (10.59 +/- 0.06 +/- 0.13).10^{-2} and B(D0 --> K- K+ pi0)/ B(D0 --> K- pi+ pi0) = (2.37 +/- 0.03 +/- 0.04). 10^{-2}, where the errors are statistical and systematic respectively. The precisions of these measurements are significantly better than those of the current world average values.We note that the second result differs significantly from the current world average value. Using the PDG-2006 value for D0 --> K- pi+ pi0 branching fraction, we obtain, B(D0 --> pi- pi+ pi0) = (1.493 +/- 0.008 +/- 0.018 +/- 0.053). 10^{-2}, B(D0 --> K- K+ pi0) = (0.334 +/- 0.004 +/- 0.006 +/- 0.012). 10^{-2}, where the errors are statistical, systematic, and due to the uncertainty of B(D0 --> K- pi+ pi0). The average squared matrix elements for both of the singly Cabibbo-suppressed decays are roughly a factor of sin^2 θ_C smaller than that for the Cabibbo-favored decay and are therefore, in contrast to the corresponding two-body modes, consistent with the naive expectations.

hep-ex↗

arXiv2006

Updated Measurement of the CKM Angle alpha Using B0->rho+rho- Decays

We present results from an analysis of B0->rho+rho- using 316fb^-1 of Y(4S) -> B0B0bar decays observed with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure the B0->rho+rho- branching fraction, longitudinal polarization fraction fL, and the CP-violating parameters S_LONG and C_LONG: B(B0->rho+rho-) = (23.5 +/- 2.2 [stat] +/- 4.1 [syst]) * 10^-6, fL = 0.977 +/- 0.024 [stat] +0.015/-0.013 [syst] S_LONG = -0.19 +/- 0.21 [stat] +0.05/-0.07 [syst] C_LONG = -0.07 +/- 0.15 [stat] +/- 0.06 [syst] Using an isospin analysis of B->rhorho decays we determine the angle alpha of the unitarity triangle. One of the two solutions, alpha = [74, 117] degrees at 68% CL, is compatible with the standard model. All results presented here are preliminary.

hep-ex↗

arXiv2006

Search for Charmonium States Decaying to J/psi gamma gamma Using Initial-State Radiation Events

We study the processes e+e- -> (J/psi gamma gamma) gamma and e+e- -> (J/psi pi- pi+) gamma where the hard photon radiated from an initial e+e- collision with center-of-mass (CM) energy near 10.58 GeV is detected. In the final state J/psi gamma gamma we consider J/psi pi0, J/psi eta, chi_{c1} gamma, and chi_{c2} gamma candidates. The invariant mass of the hadronic final state defines the effective e+e- CM energy in each event, so these data can be compared with direct e+e- measurements. We report 90% CL upper limits for the integrated cross section times branching fractions of the J/psi gamma gamma channels in the Y(4260) mass region.

hep-ex↗

arXiv2006

Measurement of branching fractions and charge asymmetries in B decays to an eta meson and a K* meson

We present measurements of branching fractions and charge asymmetries for the decays etaK*, where K* indicates a spin 0, 1, or 2 Kpi system. The data sample corresponds to 344x10^6 BBbar pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We measure the branching fractions (in units of 10^-6): BR(B0->etaK*0)=16.5\pm1.1\pm0.8, BR(B+->etaK*+)=18.9\pm1.8\pm1.3, BR(B0->eta(Kpi)_0*0)=11.0\pm1.6\pm1.5, BR(B+->eta(Kpi)_0*+)=18.2\pm2.6\pm 2.6, BR(B0->etaK_2*0(1430))=9.6\pm1.8\pm1.1, and BR(B+->etaK_2*+(1430))=9.1\pm2.7\pm 1.4. We also determine the charge asymmetries for all decay modes.

hep-ex↗

arXiv2006

Measurement of the CKM angle gamma in B ->D(*)0K decays with a Dalitz analysis of D0->KS pi- pi+

We present a measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma with a Dalitz analysis of neutral D-meson decays to the K^0_s pi^- pi^+ final state from B^+/- -> D^{(*)}K^+/- decays, using a sample of 347 million B\bar{B} events collected by the BaBar detector. We measure gamma = (92 +/- 41 +/- 11 +/- 12)deg, where the first error is statistical, the second is the experimental systematic uncertainty and the third reflects the Dalitz model uncertainty. For the ratios r_B^{(*)} between the magnitudes of amplitudes A(B- -> D^{(*)0}K-) and A(B- ->\bar{D}^{(*)0} K-) we obtain the one-standard deviation intervals [0,0.14] and [0.02,0.20], respectively. All results presented here are preliminary.

hep-ex↗

arXiv2006

Measurement of Time-dependent CP Asymmetries in B0 -> K0S K0S K0S Decay

We present an updated measurement of the time-dependent CP-violating asymmetry in B0->K0S K0S K0S decays based on 347 million Upsilon(4S)->B Bbar decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We obtain the CP asymmetries S_f = -0.66 +/- 0.26 +/- 0.08 and C_f = -0.14 +/- 0.22 +/- 0.05, where the first uncertainties are statistical and the second systematic.

hep-ex↗

arXiv2006

A search for the decays $B^+\to e^+ ν_e$ and $B^+\to μ^+ ν_μ$ using hadronic-tag reconstruction

We report on a search for the rare decay modes $B^+\to e^+ ν_e$ and $B^+\to μ^+ ν_μ$ with data collected from the BaBar detector at the PEP-II $e^+e^-$ storage ring. This search utilizes a new technique in which we fully reconstruct the accompanying $B^-$ in $Υ(4S)\righarrow B^+ B^-$ events, and look for a mono-energetic lepton in the $B^+$ rest frame. No signal candidates are observed in either of the channels, consistent with the expected background, in a data sample of approximately 229 million $B\bar{B}$ pairs. The branching-fraction upper limits are set at $\mathcal{B}(B^+\to e^+ν_{e})<7.9 \times 10^{-6}$ and $\mathcal{B}(B^+\toμ^+ν_μ)<6.2 \times 10^{-6}$ at the 90% confidence level.

hep-ex↗

arXiv2006

Measurement of CP-Violating Asymmetries in the B0->K+K-K0 Dalitz Plot

We present a preliminary measurement of CP-violation parameters in the decay B0 -> K+K-K0, using approximately 347 million BBbar events collected by the BABAR detector at SLAC. Reconstructing the neutral kaon as KS -> pi+pi-, KS -> pi0pi0, or KL, we analyze the Dalitz plot distribution and measure fractions to intermediate states. We extract CP parameters from the asymmetries in amplitudes and phases between B0 and B0bar decays across the Dalitz plot. For decays to phiK0, we find beta_eff=0.06 +/- 0.16 +/- 0.05, Acp=-0.18 +/- 0.20 +/- 0.10, where the first uncertainty is statistical and the second one is systematic. For decays to f0K0, we find beta_eff=0.18 +/- 0.19 +/- 0.04, Acp=0.45 +/- 0.28 +/- 0.10. Combining all KKK0 events and taking account of the different CP eigenvalues of the individual Dalitz plot components, we find beta_eff = 0.361 +/- 0.079 +/- 0.037, Acp = -0.034 +/- 0.079 +/- 0.025. The trigonometric reflection at pi/2 - beta_eff is disfavored at 4.6 sigma. We also study angular distributions in B0 -> K+K-KS and B+ -> phi K+ decays and measure the direct CP asymmetry in B+ -> phi K+ decays, Acp = 0.046 +/- 0.046 +/- 0.017.

hep-ex↗