arXiv subjects

B. Aubert

Publications and source records attributed to B. Aubert.

At least 433 records · Page 24Linked to original sources

arXiv2004

Measurements of Branching Fractions and CP-Violating Asymmetries in B-Meson Decays to the Charmless Two-Body States K0pi+, K0barK+, and K0K0bar

We present preliminary measurements of branching fractions and CP-violating asymmetries in decays of B mesons to two-body final states containing a K0. The results are based on a data sample of approximately 227 million Upsilon(4S) decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure BF(B+ --> K0pi+) = (26.0 +/- 1.3 +/- 1.0) x 10-6, BF(B+ --> K0barK+) = (1.45 +0.53 -0.46 +/- 0.11) x 10-6 (< 2.35 x 10-6), and BF(B0 --> K0K0bar) = (1.19 +0.40 -0.35 +/- 0.13) x 10^-6, where the first uncertainty is statistical and the second is systematic, and the upper limit is at a 90% confidence level. The significance of the BF(B+ --> K0barK+) and BF(B0 --> K0K0bar) results are 3.5 sigma and 4.5 sigma, respectively, including systematic uncertainties. In addition, we obtain a measurement of the CP-violating asymmetry for the BF(B+ --> K0pi+) mode and we determine a 90% confidence-level interval for the asymmetry in the BF(B+ --> K0barK+) mode: ACP(B+ --> K0pi+) = -0.087 +/- 0.046 +/- 0.010 and ACP(B+ --> K0barK+) is in [-0.43, 0.68].

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arXiv2004

Study of B0 -> pi0pi0, B+ -> pi+pi0 and B+ -> K+pi0 decays

We present updated measurements of the branching fractions for the modes B0->pi0pi0, B+ -> pi+pi0, and B+ -> K+pi0. We also measure the time-integrated asymmetry C_pi0pi0 and the charge asymmetries A_CP(pi+pi0) and A_CP(K+pi0). Based on a sample of approximately 227 million BBar pairs collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure BR(B0 -> pi0pi0) = (1.17 +/- 0.32 +/- 0.10)*10^{-6}, C_pi0pi0 = -0.12 +/- 0.56 +/- 0.06, where the first errors are statistical and the second are systematic. The B0 -> pi0pi0 signal has a significance of 4.9sigma including systematic uncertainties. We also measure BR(B+ -> pi+pi0) = (5.8 +/- 0.6 +/- 0.4)*10^{-6}, A_CP(pi+pi0) = -0.01 +/- 0.10 +/- 0.02, BR(B+ -> K+pi0) = (12.0 +/- 0.7 +/- 0.6)*10^{-6}, A_CP(K+pi0) = 0.06 +/- 0.06 +/- 0.01 . Using related BaBar measurements and isospin relations we find an upper bound on the angle difference |delta| = |alpha - alpha_eff| of 35 degrees at the 90% C.L.

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arXiv2004

Measurement of the Branching Fractions and CP Asymmetries of B-->D0(cp)K- Decays with the BaBar detector

We present a study of B--> D0(CP)K- decays, where D0(CP) is reconstructed in non-CP (K-pi+), CP-even (K-K+,pi-pi+) and CP-odd (KS0 pi0) eigenstates, based on a sample of about 214 million Y(4S) -> BBbar decays collected with the BABAR detector at the PEP-II e+e- storage ring. We measure the ratios of branching fractions R+ = [Br(B- ->D0_CP+ K-)+Br(B+ ->D0_CP+ K+)]/[Br(B- ->D0 K-)] = 0.87 +/- 0.14(stat) +/- 0.06(syst), R- = [Br(B- ->D0_CP- K-)+Br(B+ ->D0_CP- K+)]/[Br(B- ->D0 K-)] = 0.80 +/- 0.14(stat) +/- 0.08(syst), and the CP asymmetries A_CP+ = 0.40 +/- 0.15 (stat) +/- 0.08 (syst) and A_CP- = 0.21 +/- 0.17 (stat) +/- 0.07 (syst) All results are preliminary.

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arXiv2004

Search for an X(3872) charged partner in the decay mode X- ->J/psi pi- pi0 in the B meson decays B0 -> X- K+ and B- -> X- Ks

We report on the search for a charged partner of the X(3872) in the decay $B \to X^\pm K$, $X^\pm \to J/ψπ^\pm π^0$, using 213 million $B\bar B$ events collected at the $Υ(4S)$ resonance with the BaBar detector at the PEP-II $e^+ e^-$ asymmetric-energy storage ring. The resulting product branching fraction upper limits are $BR (\bar{B}^0/B^0 \to X^\pm K^\mp$, $X^\pm \to J/ψπ^\pm π^0)$ $< 5.8 \times 10^{-6}$ and $BR (B^\pm \to X^\pm K^0_S$, $X^\pm \to J/ψπ^\pm π^0)$ $< 11 \times 10^{-6}$ at the 90% confidence level. All results are preliminary.

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arXiv2004

A search for the decay B+ -> K+ nu nubar

We present a search for the rare flavor-changing neutral-current decay $B^+ \to K^+ ν\barν$ based on data sample of 82 fb$^{-1}$ collected with the BABAR detector at the PEP-II B-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged B decay. Using these two independent samples, a combined limit of ${\mathcal B}(B^+ \to K^+ ν\barν)<5.2 \times 10^{-5}$ is obtained at the 90% confidence level. In addition, by modifying the particle identification criteria, a limit of ${\mathcal B} (B^+\toπ^+ν\barν)<1.0 \times 10^{-4}$ is obtained using hadronic $B$ reconstruction. All results are preliminary.

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arXiv2004

Improved Measurements of CP-Violating Asymmetries in B0 --> pi+pi- Decays

We present preliminary updated measurements of the CP-violating parameters $S_{ππ}$ and $C_{ππ}$ in $B^0\toπ^+π^-$ decays. Using a sample of 227 million $Υ(4S)\to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC, we observe $467\pm 33$ signal decays and measure $S_{ππ}$ and $C_{ππ} = -0.30\pm 0.17 ({\rm stat})\pm 0.03 ({\rm syst})$, and $C_{ππ} = -0.09\pm 0.15 ({\rm stat})\pm 0.04 ({\rm syst})$.

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arXiv2004

Measurement of the B0 --> K0S K0S K0S Branching Fraction

We report a preliminary measurement of the branching fraction for the decay $B^0 \to K^0_sK^0_sK^0_s ,$ where the $K^0_s$ mesons are reconstructed through the decay $K^0_s\toπ^+ π^- .$ The measurement was performed on a sample of $211\times 10^6$ $B\bar{B}$ pairs collected by the BABAR detector running on the $Υ(4S)$ resonance at the PEP-II storage ring. The branching fraction is measured to be $${\cal B}(B^0 \to K^0_sK^0_sK^0_s)= (6.5\pm 0.8\pm 0.8) \times 10^{-6},$$ where the errors are statistical and systematic, respectively.

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arXiv2004

Measurement of the D_(sJ)(2317) and D_(sJ)(2460) Properties in e^+ e^- --> c c-bar Production

The properties of the $\DsTT$ and $\DsFE$ mesons are studied using 125 ${\rm fb}^{-1}$ of $e^+e^- \to c \bar{c}$ data collected by the BaBar experiment. Preliminary mass estimates of $[2318.9\pm 0.3 ({\rm stat.}) \pm 0.9 ({\rm syst.})]$ \mevcc and $[2459.4 \pm 0.3 ({\rm stat.}) \pm 1.0 ({\rm syst.})]$ \mevcc are obtained. Searches are performed for the decay to the $D_s^+$ meson along with one or more $\piz$, $π^+$, or $γ$ particles. A search is also performed for neutral and doubly-charged partners.

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arXiv2004

Measurements of CP Asymmetries in the Decay B --> Phi K

We present a preliminary measurement of the time-dependent CP asymmetry for the neutral $B$-meson decay $B^0\toϕK^0$. We use a sample of approximately 227 million $B$-meson pairs recorded at the $Υ(4S)$ resonance with the BaBar detector at the PeP-II $B$-meson Factory at SLAC. We reconstruct the $CP$ eigenstates $ϕK^0_S$ and $ϕK^0_L$ where $ϕ\to K^+K^-$, $K^0_S\toπ^+π^-$, and $K^0_L$ is observed via its hadronic interactions. The other $B$ meson in the event is tagged as either a $B^0$ or $\bar{B}^0$ from its decay products. The values of the CP-violation parameters derived from the combined $ϕK^0$ dataset are $S_{ϕK} = +0.50\pm 0.25 ({\small stat})^{+0.07}_{-0.04} ({\small syst})$ and $C_{ϕK} = 0.00\pm 0.23 ({\small stat}) \pm 0.05 ({\small syst})$. In addition, we measure the CP -violating charge asymmetry $\mathcal{A_{CP}} (B^+\to ϕK^+) = 0.054\pm 0.056 ({\small stat}) \pm 0.012 ({\small syst})$. All results are preliminary.

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arXiv2004

Measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic endpoint and determination of |Vub|

We study the inclusive electron spectrum of B->X_u e nu decays near the kinematic limit for B->X_c e nu transitions using a sample of 88 million Upsilon(4S) decays recorded by the BABAR detector at the PEP II e+e- storage rings. For the electron momentum interval of 2.0 - 2.6 GeV/c the partial branching fraction is measured to be DeltaB(B->X_u e nu) = (0.480 +/- 0.029_{stat} +/- 0.053_{syst})x10^{-3}. Combining this result on with measurements of the inclusive photon spectrum in B->X_s gamma transition we find |V_ub|=(3.94 +/- 0.25_{exp} +/- 0.37_{f_u} +/- 0.19_{theory})x10^{-3}, where the first error represents the combined statistical and systematic experimental uncertainty of the partial branching fraction measurement, the second refers to the uncertainty of the determination of the fraction f_u of the inclusive electron spectrum that falls within our cuts, and the third error is due to theoretical uncertainties in the QCD corrections, plus the uncertainty in the b-quark mass. All results are preliminary.

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arXiv2004

Measurement of CP Asymmetry in B0 --> K+K-K0(S) Decays

We present preliminary measurements of the CP asymmetry parameters and CP content in B0-->K+K-Ks decays, with phiKs events excluded. In a sample of 227M BB pairs collected by the BABAR detector at the PEPII B-Factory at SLAC, we find the CP parameters to be S = -0.42 +/- 0.17 +/- 0.04 and C = 0.10 +/- 0.14 +/- 0.06, where the first error is statistical and the second is systematic. Extracting the fraction of CP -even final states from angular moments f(CP-even) = 0.89 +/- 0.08 +/- 0.06, and setting C=0, we determine sin(2beta) = 0.55 +/- 0.22 +/- 0.04 +/- 0.11, where the last error is due to uncertainty on the CP content.

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arXiv2004

Study of e+e- --> pi+ pi- pi0 process using initial state radiation with BABAR

The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum we have obtained the products of branching fractions for the omega and phi mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range 1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18 +/- 0.19)% has been measured.

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arXiv2004

Search for D0-D0bar Mixing Using Semileptonic Decay Modes

Based on an 87-fb$^{-1}$ dataset collected by the Babar detector at the PEP-II asymmetric-energy $B$-Factory, a search for $D^{0}$--$\bar{D}^{0}$ mixing has been made using the semileptonic decay modes $D^{*+} \to π^{+} D^{0}, D^{0} \to K^{(*)}eν$ (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the $D^{0}$ decay time and $D^{*+}$--$D^{0}$ mass difference ($ΔM$) distributions. The high-statistics sample of unmixed semileptonic $D^{0}$ decays is used to model the $ΔM$ distribution and time-dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the $D^{0}$. A result consistent with no charm mixing has been obtained, $R_{\rm{mix}}=0.0023 \pm 0.0012 \pm 0.0004$. This corresponds to an upper limit of $R_{\rm{mix}}<0.0042$ (90% CL).

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arXiv2004

Measurement of CP-violating parameters in fully reconstructed $B\to D^{(*)}π$ and $B\to Dρ$ decays

We present a preliminary measurement of CP-violating asymmetries in fully reconstructed $B^0{\to}D^{(*)\pm}π^{\mp}$ and $\B^0{\to}D^{\pm}ρ^{\mp}$ decays in approximately 110 million $Υ(\rm 4S) \to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ factory at SLAC. % From a maximum likelihood fit to the time-dependent decay distributions we obtain for the CP-violating parameters: $a^{Dπ} = -0.032\pm0.031 (\textrm{stat.})\pm 0.020 (\textrm{syst.}), c_{\rm lep}^{Dπ} = -0.059\pm0.055 (\textrm{stat.})\pm 0.033 (\textrm{syst.})$ on the $B^0{\to}D^{\pm}π^{\mp}$ sample, $a^{D^*π} = -0.049\pm0.031 (\textrm{stat.})\pm 0.020 (\textrm{syst.}), c_{\rm lep}^{D^*π} = +0.044\pm0.054 (\textrm{stat.})\pm 0.033 (\textrm{syst.})$ on the $B^0{\to}D^{*\pm}π^{\mp}$ sample, and $a^{Dρ} = -0.005\pm0.044 (\textrm{stat.})\pm 0.021 (\textrm{syst.}), c_{\rm lep}^{Dρ} = -0.147\pm0.074 (\textrm{stat.})\pm 0.035 (\textrm{syst.})$ on the $B^0{\to}D^{\pm}ρ^{\mp}$ sample.

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arXiv2004

Measurement of the Ratio BR(B- --> D0 K-)/BR(B- --> D0 pi-) and the CP-asymmetry of B- --> D*0(CP+) K- decays with the BABAR detector

We present a study of 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 eigenstates K- K+ and pi- pi+ and in the (non-CP) channels K- pi+, K- pi+ pi+ pi-, and K- pi+ pi0. We use an unbinned maximum likelihood fit to measure the signal yields. Using a sample of about 123 million Y(4S) decays into B anti-B pairs, we measure the ratios of decay rates R*(CP+)=BR(B- --> D*0(CP+) K-)/BR(B- --> D*0(CP+) pi-) = 0.088+-0.021(stat)+0.007-0.005(syst), and provide the first measurements of R*(non-CP) = BR(B- --> D*0(non-CP) K-)/BR(B- --> D*0(non-CP) pi-) = 0.0805+-0.0040(stat)+0.0039-0.0032(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+)) = -0.02+-0.24(stat)\+-0.05(syst). These results are preliminary.

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arXiv2004

Search for the Decay B0 --> rho0rho0

The B --> rho0 rho0 decay mode is searched for in a data sample of about 227 million Upsilon(4S) --> B Bbar decays collected with the BABAR detector at the PEP-II asymmetric B factory at SLAC. No significant signal is observed, and an upper limit of 1.1 x 10e-6 (90% C.L.) on the branching fraction is set. Implications on the penguin contribution and constraints on the CKM angle alpha with B --> rho rho decays are discussed. All results are preliminary.

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arXiv2004

Measurements of the Branching Fraction and CP-Violating Asymmetries of B0 --> K0S Pi0 Decays

We present measurements of the branching fraction and time-dependent CP-violating (CPV) asymmetries in B0 --> K0S Pi0 decays based on 227 million Y(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B factory at SLAC. We obtain a branching fraction B(B0 --> K0 Pi0) = (11.4 +/- 0.9 +/- 0.6) x 10^{-6}, the magnitude of the direct CPV asymmetry C = 0.06 +/- 0.18 +/- 0.06 and the magnitude of the CPV asymmetry in the interference between mixing and decay S = 0.35 +0.30/-0.33 +/- 0.04, where the first error is statistical and the second systematic. All results are preliminary.

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arXiv2004

Search for the Decay B0->K*+rho-

We present the preliminary result of a search for the decay of $B^0\to K^{*+}ρ^-$. The data were recorded with the $BaBar$ detector at the PEPII collider and correspond to 123 million $B\bar{B}$ pairs produced in the $e^+e^-$ annihilation through the $Υ(4S)$ resonance. We obtain an upper limit on the branching fraction for this decay of ${\cal B}(B^0\to K^{*+}ρ^-) <24 \times 10^{-6}$ (90% C.L.). All results are preliminary.

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