arXiv subjects

BABAR Collaboration

Publications and source records attributed to BABAR Collaboration.

At least 73 records · Page 4Linked to original sources

arXiv2004

D+ -> K-K+pi+ Meson Decays: A Search for CP Violation and a Measurement of the Branching Ratio

We present a preliminary measurement of the CP asymmetry in singly Cabibbo-suppressed D+ -> K-K+π+ decays and in the resonant decays D+ -> ϕπ+ and D+ -> K*0 K+. We use a data sample of 79.9 fb^{-1} recorded by the BABAR detector. The Cabibbo-favored Ds+ -> K-K+π+ branching fraction is used as normalization in the measurements to reduce systematic uncertainties. Preliminary results of the CP asymmetries obtained are A_{CP}(K+K-π\pm) = (1.4 \pm 1.0(stat.) \pm 1.1(syst.))\times 10^{-2}, A_{CP}(ϕπ\pm) = (0.2 \pm 1.5(stat.) \pm 0.8(syst.))\times 10^{-2}, and A_{CP}(K^{\pm} K*0) = (0.9 \pm 1.7(stat.) \pm 0.8(syst.))\times 10^{-2}. A preliminary determination of the branching ratio is \frac{Γ(D+ -> K-K+π+)}{Γ(D+ -> K-π+π+)} =(10.7 \pm 0.1(stat.) \pm 0.2(syst.))\times 10^{-2}.

hep-ex↗

arXiv2004

Improved Measurement of CP Asymmetries in B0 -> (ccbar)K0(*) Decays

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227 million Upsilon(4S) -> BBbar decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CP asymmetry, sin2Beta in the Standard Model, is derived from decay-time distributions from events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other $B$ meson is determined to be either a B0 or B0bar from its decay products. We measure sin2Beta = 0.722 +/- 0.040 (stat.) +/- 0.23 (syst.) in agreement with the Standard Model expectation.

hep-ex↗

arXiv2004

Measurement of Neutral B Decay Branching Fractions to Kspi+pi- Final States

Branching fraction measurements using B-meson decays to Kspi+pi- are presented. These measurements were obtained by analyzing a data sample of 88.9 million Y(4S) --> 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: Br(B0 -> K0pi+pi- = (43.7 +/- 3.8 +/- 3.4) * 10^-6, Br(B0 --> K{*+}pi-) = (12.9 +/- 2.4 +/- 1.4) * 10$^-6} and Br(B0 --> D-(--> Kspi-)pi+ = (42.7 +/- 2.1 +/- 2.2) * 10^{-6}. The CP violating char ge asymmetry A(K*pi} for the decay B0 --> $K{*+}pi-$ was measured to be A(K*pi} = 0.23 +/- $0.18^{+0.09}_{-0.06}$. For all these measurements the first error is statistical and the second is systematic.

hep-ex↗

arXiv2004

Measurement of CP-Violating Asymmetries in B0->(rho pi)0 Using a Time-Dependent Dalitz Plot Analysis

We present the preliminary measurement of CP-violating asymmetries in B0->(rhopi)0->pi+pi-pi0 decays using a time-dependent Dalitz plot analysis. The results are obtained from a data sample of 213 million Y(4S)->BB-bar decays, collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. This analysis extends the narrow-rho quasi-two-body approximation used in the previous analysis, by taking into account the interference between the rho resonances of the three charges. We measure 16 coefficients of the bilinear form factor terms occurring in the time-dependent decay rate of the B0 meson with the use of a maximum-likelihood fit. We derive the physically relevant quantities from these coefficients. We measure the direct CP-violation parameters Acp = -0.088 +- 0.049 +- 0.013 and C = 0.34 +- 0.11 +- 0.05, where the first errors are statistical and the second systematic. For the mixing-induced CP-violation parameter we find S = -0.10 +- 0.14 +- 0.04, and for the dilution and strong phase shift parameters respectively, we obtain dC = 0.15 +- 0.11 +- 0.03 and dS = 0.22 +- 0.15 +- 0.03. For the angle alpha of the Unitarity Triangle we measure (113 +27 -17 +-6) deg, while only a weak constraint is achieved at the significance level of more than two standard deviations. Finally, for the relative strong phase delta+- between the B0->rho-pi+ and B0->rho+pi- transitions we find (-67 +28 -31 +- 7) deg, with a similarly weak constraint at two standard deviations and beyond.

hep-ex↗

arXiv2004

A Search for B --> tau nu Recoiling against B --> D*0 l nu

We present a search for the decay $B^{+} \to τ^{+} ν_τ$ in $124.1 \times 10^{6}$ $Υ(4S)$ decays recorded with the $BABAR$ detector at the SLAC PEP-II $B$-Factory. A sample of events with one reconstructed exclusive semi-leptonic B decay ($B^- \to D^{*0} \ell^- \barν_{\ell}$) 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: $τ^+ \to e^+ ν_e \barν_τ$, $τ^+ \to μ^+ ν_μ \barν_τ$, $τ^+ \to π^+ \barν_τ$, $τ^+ \to π^+ π^{0} \barν_τ$, $τ^+ \to π^+ π^{-} π^{+} \barν_τ$. We find no evidence of signal, and we set a preliminary upper limit on the branching fraction of $\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 4.3 \times 10^{-4}$ at the 90% confidence level (CL). This result is then combined with a statistically independent $BABAR$ search for $B^{+} \to τ^{+} ν_τ$ to give a combined preliminary limit of $\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 3.3 \times 10^{-4}$ at 90% CL.

hep-ex↗

arXiv2004

Measurements of Branching Fraction, Polarization, and Direct-CP-Violating Charge Asymmetry in B+ --> K*0 Rho+ Decays

With a sample of 88.8 BBbar pairs produced at PEP-II in e+e- annihilation through the Upsilon(4S) resonance and recorded with the BABAR detector, we search for the B+ --> K*0 Rho+ decay mode. A signal is observed for the first time with a significance of more than 5 sigma. We measure a preliminary branching fraction of BR(B+ --> K*0 Rho+)=[17.0 +-2.9 (stat) +-2.0 (syst) +0.0 -1.9 (non-resonant)] 10(-6). The "non-resonant" error corresponds to the uncertainty from non-resonant backgrounds not modeled in the fit. The measurement of the longitudinal-polarized component to this vector-vector penguin decay is of special interest. We measure fL= 0.79 +-0.08(stat) +-0.04 (syst) +- 0.02 (non-resonant). We measure the direct-CP-violating charge asymmetry in this mode to be A_CP = -0.14 +- 0.17 +- 0.04.

hep-ex↗

arXiv2004

A Measurement of CP Violating Asymmetries in B0-->f0(980)K0s Decays

We present preliminary measurements of the CP-violating asymmetries in the decay $B^0\to f_0(980)(\toπ^+π^{-}) K_s^0$. The results are obtained from a data sample of $209\times10^6$ $Υ(4S) \to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. From a time-dependent maximum-likelihood fit we measure the mixing-induced CP violation parameter $S=-0.95^{+0.32}_{-0.23} \pm 0.10$ and the direct CP violation parameter $C=-0.24\pm 0.31 \pm 0.15 $, where the first errors are statistical and the second systematic.

hep-ex↗

arXiv2004

Evidence For B0 -> rho0 K0S

We present evidence for the decay B0->rho0 K0s. The results are obtained from a data sample of 227 10^6 Y(4S) -> BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-Factory at SLAC. From a maximum-likelihood fit giving a yield of 99+/-19 events and efficiency estimated from simulation we make a preliminary measurement of the branching fraction B0->rho0 K0 =(5.1+/-1.0+/-1.2)10^-6 where the first error is statistical and the second systematic. The hypothesis of zero signal in the rho0 mass region, 600MeV-930MeV, is excluded at the 6.1sigma level. Allowing a B0->f_0(600)K0s contribution in the fit allows us to exclude the hypothesis of zero B0->rho0 K0s at the 3.5sigma level.

hep-ex↗

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].

hep-ex↗

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.

hep-ex↗

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.

hep-ex↗

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 $C_{ππ} = -0.09\pm 0.15 ({\rm stat})\pm 0.04 ({\rm syst})$.

hep-ex↗

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).

hep-ex↗

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.

hep-ex↗

arXiv2004

Study of B -> DsJ()+ Dbar() Decays

We report a study of DsJ*(2317)+ and DsJ(2460)+ meson production in B decays. We observe the decays B+ -> DsJ(*)+ Dbar(*)0 and B0 -> DsJ(*)+ D(*)- with the subsequent decays DsJ*(2317)+ -> Ds+ pi0, DsJ(2460)+ -> Ds+ gamma, and DsJ(2460)+ -> Ds*+ pi0. Based on a data sample of 122.1 million BBbar pairs collected with the BaBar detector at the PEP-II B factory, we obtain branching fractions for these modes, including the previously unseen decays B -> DsJ(*)+ D*. In addition, we perform an angular analysis of DsJ(2460)+ -> Ds+ gamma decays to test the different DsJ(2460)+ spin hypotheses.

hep-ex↗

arXiv2004

Study of the tau- -> 3h- 2h+ nu-tau Decay

A preliminary measurement of the branching fraction of the tau- -> 3h-2h+nu decay (h= pi, K$) with the BaBar detector is found to be {8.52 +/- 0.09 +/- 0.40} x 10E-4, where the first error is statistical and the second is systematic. The data show evidence that the rho resonance plays a strong role in the decay of the tau lepton to five charged hadrons.

hep-ex↗

arXiv2004

A study of B0bar --> D()0 K()bar decays

We present a study of the decays B0bar --> D(*)0 K(*)0bar using a sample of 124 million Upsilon(4S) --> B0bar B0 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 K_S final state with an average branching fraction BF(B --> D*0 K0bar) = (4.5 +/- 1.9 +/- 0.5) x 10^-5. Similarly, we measure BF(B --> D0 K0bar) = (6.2 +/- 1.2 +/- 0.4) x 10^-5 for the D0 K_S final state. We also measure BF(B0bar --> D0 K*0bar) = (6.2 +/- 1.4 +/- 0.6) x 10^-5 and set a 90% C.L. upper limit BF(B0bar --> D0bar K*0bar) < 4.1 x 10^-5. All results presented in this paper are preliminary.

hep-ex↗

arXiv2004

Measurement of the ratio of branching fractions of Xic0 decays to Xi- pi+ and to Omega- K+

We have analyzed 116 fb^-1 of data collected by the BABAR detector for Xic0 production. In this paper we describe the observation of Xic0 production from ccbar continuum and from B decays, with the Xic0 decaying into (Xi- pi+) and (Omega- K+) modes. The ratio of the branching fractions of the Xic0 decays into these two final states measured in the ccbar continuum is: B(Xic0 -> Omega- K+) / B(Xic0 -> Xi- pi+) = 0.296 +- 0.018 (stat.) +- 0.030 (sys.). All results in this note are preliminary.

hep-ex↗