arXiv subjects

BABAR Collaboration

Publications and source records attributed to BABAR Collaboration.

At least 109 records · Page 6Linked to original sources

arXiv2004

Study of high momentum eta' production in B -> eta' X_s

We measure the branching fraction for the charmless semi-inclusive process B -> eta' X_s, where the eta' meson has a momentum in the range 2.0 to 2.7 GeV/c in the Upsilon(4S) center-of-mass frame and X_s represents a system comprising a kaon and zero to four pions. We find B(B -> eta' X_s)=(3.9+/-0.8(stat)+/-0.5(syst)+/-0.8(model)).10^{-4}. We also obtain the X_s mass distribution and find that it tends to favor models predicting high masses.

hep-ex↗

arXiv2004

Search for the Rare Leptonic Decay B+ --> mu+ nu_mu

We have performed a search for the rare leptonic decay B+ --> mu+ nu_mu with data collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II storage ring. In a sample of 88.4 million BBbar pairs, we find no significant evidence for a signal and set an upper limit on the branching fraction BR(B+ --> mu+ nu_mu) < 6.6 x 10^{-6} at the 90% confidence level.

hep-ex↗

arXiv2003

Measurements of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Charmless Two-Body States Containing a K0

We present measurements of branching fractions and \CP-violating asymmetries in decays of $B$ mesons to two-body final states containing a \Kz. The results are based on a data sample of approximately 88 million \upsbb decays collected with the \babar detector at the \pep2 asymmetric-energy $B$ Factory at SLAC. We measure $\BR(\Bp\to\Kz\pip) = (22.3 \pm 1.7 \pm 1.1)\times 10^{-6}$, $\BR(\Bz\to\Kz\piz) = (11.4\pm 1.7\pm 0.8)\times 10^{-6}$, $\BR(\Bp\to\Kzb\Kp) < 2.5\times 10^{-6}$, and $\BR(\Bz\to\KzKzb) < 1.8\times 10^{-6}$, where the first uncertainty is statistical and the second is systematic, and the upper limits are at the 90% confidence level. In addition, the following \CP-violating asymmetries have been measured: ${\cal A}_{CP}(\Bp\to\Kz\pip) = -0.05 \pm 0.08 \pm 0.01$ and ${\cal A}_{CP}(\Bz\to\Kz\piz) = 0.03 \pm 0.36\pm 0.11$.

hep-ex↗

arXiv2003

Measurement of the Branching Fraction for B- --> D0 K*-

We present a measurement of the branching fraction for the decay B- --> D0 K*- using a sample of approximately 86 million BBbar pairs collected by the BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the K*- through its decay to K0S pi-. We measure the branching fraction to be B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}.

hep-ex↗

arXiv2003

Measurements of the mass and width of the eta_c meson and of an eta_c(2S) candidate

The mass and total width of the eta_c meson have been measured in two-photon interactions at the SLAC asymmetric B-Factory with the BABAR detector. With a sample of approximately 2500 reconstructed eta_c -> Ks K pi decays in 88 fb-1 of data, the measured eta_c mass and width are respectively 2982.5 +- 1.1 (stat) +- 0.9 (syst) MeV/c2 and 34.3 +- 2.3 (stat) +- 0.9 (syst) MeV/c2. Using the same decay mode, a second resonance with 112 +- 24 events is observed with a mass of 3630.8 +- 3.4 (stat) +- 1.0 (syst) MeV/c2 and width of 17.0 +- 8.3 (stat) +- 2.5 (syst) MeV/c2. This observation is consistent with expectations for the eta_c(2S) state.

hep-ex↗

arXiv2003

Measurement of the branching fractions and CP-asymmetry of B^- -> D^0_(CP) K^- decays with the BaBar detector

We present a study of B- -> D^0_CP K^- decays, where D^0_CP is reconstructed in CP-even channels, based on a sample of 88.8 million Upsilon(4S)->BBbar decays collected with the BaBar detector at the PEP-II e^+e^- storage ring. We measure the ratio of Cabibbo-suppressed to Cabibbo-favored branching fractions Br(B- -> D^0_CP K^-)/Br(B- -> D^0_CP pi^-)= (8.8 +/- 1.6(stat) +/- 0.5(syst))\times 10^{-2} and the CP asymmetry A_CP= 0.07 +/- 0.17(stat) +/- 0.06(syst). We also measure Br(B- ->D0K-)/Br(B- ->D0pi-)=(8.31 +/- 0.35(stat) +/- 0.20(syst))\times 10^{-2} using a sample of 61.0 million BBbar pairs.

hep-ex↗

arXiv2003

Measurement of the Average $ϕ$ Multiplicity in $B$ Meson Decay

We present a measurement of the average multiplicity of $ϕ$ mesons in $B^0$, $\kern 0.18em\bar{\kern -0.18em B}{}^0$ and $B^\pm$ meson decays. Using $17.6 fb^{-1}$ of data taken at the $Υ{(4S)}\xspace$ resonance by the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II $e^+e^-\xspace$ storage ring at the Stanford Linear Accelerator Center, we reconstruct $ϕ$ mesons in the $K^+K^-$ decay mode and measure ${\cal{B}}(B\to ϕX) = (3.41\pm0.06\pm0.12)%$. This is significantly more precise than any previous measurement.

hep-ex↗

arXiv2003

Measurement of Branching Fractions and CP-Violating Charge Asymmetries in B+ --> rho+ pi0 and B+ --> rho0 pi+, and Search for B0 --> rho0 pi0

We present preliminary measurements of branching fractions and CP-violating charge asymmetries in B-meson decays to rho pi. The data sample comprises 89 million Y(4S) --> BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find the charge-averaged branching fractions B(B+ --> rho+ pi0) = (11.0 +/- 1.9(stat.) +/- 1.9(syst.)) * 10^-6 and B(B+ --> rho0 pi+) = (9.3 +/-1.0(stat.) +/- 0.8(syst.)) * 10^-6; we set a 90% confidence-level upper limit of B(B0 --> rho0 pi0) < 2.5 * 10^-6. We measure the CP-violating charge asymmetries A_CP(rho+ pi0) = 0.23 +/- 0.16(stat.) +/- 0.06(syst.) and A_CP(rho0 pi+) = -0.17 +/- 0.11(stat.) +/- 0.02(syst.).

hep-ex↗

arXiv2003

Rare B Decays into States Containing a J/psi Meson and a Meson with ssbar Quark Content

We report a study of the B meson decays, B+ -> J/psi phi K+, B0 -> J/psi phi K0S, B0 -> J/psi phi, B0 -> J/psi eta and B0 -> J/psi eta' using 56 million BBbar events collected at the Y(4S) resonance with the BABAR detector at the PEP-II e+ e- asymmetric-energy storage ring. We measure the branching fractions B(B+ -> J/psi phi K+) = (4.4 +- 1.4(stat) +- 0.5(syst)) * 10-5 and B(B0 -> J/psi phi K0S) = (5.1 +- 1.9(stat) +- 0.5(syst)) * 10^-5, and set upper limits at 90% confidence level for the branching fractions B(B0 -> J/psi phi) < 9.2 * 10^-6, B(B0 -> J/psi eta)< 2.7 * 10^-5, and B(B0 -> J/psi eta')< 6.3 * 10-5.

hep-ex↗

arXiv2003

Limits on the Lifetime Difference of Neutral B Mesons and on CP, T, and CPT Violation in B0-B0bar Mixing

Using events in which one of two neutral B mesons from the decay of an Y(4S) resonance is fully reconstructed, we set limits on the lifetime difference between the two neutral-B mass eigenstates and on CP, T, and CPT violation in B0-B0bar mixing. Both CP and non-CP eigenstates were obtained from the 88 million Y(4S)->B0B0bar decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B-Factory at SLAC. We determine six independent parameters governing mixing (dm, dGamma/Gamma), CPT/CP violation (Re(z), Im(z)), and CP/T violation (Imλ(CP), |q/p|), where λ(CP) characterizes B0 and B0bar decays to states of charmonium plus K_S or K_L. The preliminary results are: sgn(Reλ(CP))*dGamma/Gamma = -0.008+-0.037(stat)+-0.018(syst) [-0.084,0.068], |q/p| = 1.029+-0.013(stat)+-0.011(syst) [1.001,1.057], (Reλ(CP)/|λ(CP)|)*Rez = 0.014+-0.035(stat)+-0.034(syst) [-0.072,0.101], Imz = 0.038+-0.029(stat)+-0.025(syst) [-0.028,0.104] . The values inside square brackets indicate the 90% confidence-level intervals. For Imλ(CP)/|λ(CP)| and dm we find values consistent with recent results from other analyses. These results are consistent with Standard Model expectations.

hep-ex↗

arXiv2003

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

We present a search for the decay $B^{+} \to τ^{+} ν_τ$ in $88.9 \times 10^{6}$ $Υ(4S)$ decays recorded with the BABAR detector at the SLAC $B$-Factory. A sample of semi-exclusive, semi-leptonic B decays ($B^{-} \to D^{0} \ell^{-} \bar{ν_{\ell}}X$), where $X$ is either a photon, $π^{0}$, or nothing, is used to identify the daughter particles that are associated with the other $B$ meson in each event. These particles are searched for evidence of a one-prong leptonic $B^{+} \to τ^{+} ν_τ$ decay. For this data sample we set a preliminary upper limit on the branching fraction of $\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 4.9 \times 10^{-4}$ at the 90% confidence level. This result is then combined with a statistically independent BABAR search for $B^{+} \to τ^{+} ν_τ$ to give a combined preliminary limit of $\mathcal{B}(B^{+} \to τ^{+} ν_τ) < 4.1 \times 10^{-4}$.

hep-ex↗

arXiv2002

Measurement of the CKM Matrix Element |Vub| with Charmless Exclusive Semileptonic B Meson Decays at BABAR

We present a preliminary measurement of the branching fraction for B to rho e nu and of the CKM matrix element |Vub| using approximately 55 million B Bbar meson pairs collected with the BABAR detector. Using isospin relations for several modes we find BF(B0 to rho- e+ nu) = (3.39+-0.44+-0.52+-0.60)x10^(-4) and |Vub| = (3.69+-0.23+-0.27+0.40-0.59)x10^(-3). The quoted errors are statistical, systematic, and theoretical, respectively. These results are obtained by using five different form-factor calculations.

hep-ex↗

arXiv2002

Measurement of the B^0 -> D^-a_1^+ Branching Fraction with Partially Reconstructed D^

The B^0 -> D^*-a_1^+ branching fraction has been measured with data collected by the BABAR experiment in 1999 and 2000 corresponding to a total integrated luminosity of 20.6 fb^-1. Signal events have been selected using a partial reconstruction technique, in which only the a_1^+ and the slow pion (pi_s) from the D^*- decay are identified. A signal yield of 18400 +/- 1200 events has been found, corresponding to a preliminary branching fraction of (1.20 +/- 0.07(stat) +/- 0.14 (syst))%.

hep-ex↗

arXiv2002

Measurements of Branching Fractions and CP-Violating Asymmetries in B0 --> pi+pi-, K+pi-, K+K- Decays

We present updated measurements of branching fractions and CP-violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 60 million Y(4S) --> B-anti-B decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The sample contains 124^{+16}_{-15} pi-pi, 403+/-24 K-pi, and 0.6^{+8.0}_{-7.4} K-K candidates, from which we measure the following quantities: BF(B0 --> pi+pi-) = (5.4+/-0.7+/-0.4) x 10^{-6}, BF(B0 --> K+pi-) = (17.8+/-1.1+/-0.8) x 10^{-6}, BF(B0 --> K+K-) < 1.1 x 10^{-6} (90% C.L.} A_Kpi = -0.05+/-0.06+/-0.01 [-0.14,+0.05], S_pipi = -0.01+/-0.37+/-0.07 [-0.66,+0.62], C_pipi = -0.02+/-0.29+/-0.07 [-0.54,+0.48], where the errors are statistical and systematic, respectively, and the asymmetry limits correspond to the 90% confidence level. These results are preliminary.

hep-ex↗

arXiv2002

Improved measurement of the CP-violating asymmetry amplitude sin2beta

We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 62 million Upsilon(4S) --> B anti-B decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. In this sample we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay time distributions in such events. We measure sin2beta = 0.75 +/- 0.09 (stat) +/- 0.04 (syst) and |λ| = 0.92 +/- 0.06 (stat) +/- 0.02 (syst). The latter is consistent with the Standard Model expectation of no direct CP violation. These results are preliminary.

hep-ex↗

arXiv2001

Charmless B Decays from BABAR (B0 --> K*0 gamma and B0 --> pi+pi-,K+pi-,K+K-)

The BABAR experiment has completed its first year of data-taking during which 21 $fb^{-1}$ of data were accumulated. We present preliminary results on two types of charmless B decays based on this data sample. The first, $B^0 \to K^{*0}γ$, is a so-called electromagnetic penguin. And the second, $B^0 \to h^+h^{'-}$, where $h^{(')}$ can be either a pion or kaon, can come from either penguin diagrams or Cabibbo suppressed tree diagrams.

hep-ex↗

arXiv2001

Observation of CP violation in the B^0 meson system

We present an updated measurement of time-dependent CP-violating asymmetries in neutral B decays with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. This result uses an additional sample of Upsilon(4S) decays collected in 2001, bringing the data available to 32 million B-anti-B pairs. We select events in which one neutral B meson is fully reconstructed in a final state containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay time distributions in such events. The result sin2beta = 0.59 +/- 0.14 (stat) +/- 0.05 (syst) establishes CP violation in the B^0 meson system. We also determine |lambda| = 0.93 +/- 0.09 {stat} +/- 0.03 {syst}, consistent with no direct CP violation.

hep-ex↗

arXiv2001

Measurement of Branching Fractions and Search for CP-Violating Charge Asymmetries in Charmless Two-Body B Decays into Pions and Kaons

We present measurements of the branching fractions and a search for CP-violating charge asymmetries in charmless hadronic decays of B mesons into two-body final states of kaons and pions. The results are based on a data sample of approximately 23 million BB(bar) pairs collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. We find the following branching fractions: BF(B0-->pi+pi-)= (4.1+/-1.0+/-0.7) x 10^{-6}, BF(B0-->K+pi-)=(16.7+/-1.6+/-1.3) x 10^{-6}, BF(B+-->K+pi0)=(10.8^{+2.1}_{-1.9}+/-1.0) x 10^{-6}, BF(B+-->K0pi+)=(18.2^{+3.3}_{-3.0}+/-2.0) x 10^{-6}, BF(B0-->K0pi0)=(8.2^{+3.1}_{-2.7}+/-1.2) x 10^{-6}. We also report the 90% confidence level upper limits BF(B0-->K+K-) < 2.5 x 10^{-6}, BF(B+-->pi+pi0) < 9.6 x 10^{-6}, and BF(B+-->anti-K0K+) < 2.4 x 10^{-6}. In addition, charge asymmetries have been measured and found to be consistent with zero, where the statistical precision is in the range of +/-0.10 to +/-0.18, depending on the decay mode.

hep-ex↗