Biomedical subjects

G Eigen

Publications and source records attributed to G Eigen.

At least 19 recordsLinked to original sources

PubMed2006

Search for D0-D0 mixing and branching-ratio measurement in the decay D0-->K+ pi- pi0.

We analyze 230.4 fb;{-1} of data collected with the BABAR detector at the PEP-II e;{+}e;{-} collider at SLAC to search for evidence of D0-D[over ];{0} mixing using regions of phase space in the decay D;{0}-->K;{+}pi;{-}pi;{0}. We measure the time-integrated mixing rate R_{M}=(0.023_{-0.014};{+0.018}(stat.)+/-0.004(syst.))%, and R_{M}<0.054% at the 95% confidence level, assuming CP invariance. The data are consistent with no mixing at the 4.5% confidence level. We also measure the branching ratio for D;{0}-->K;{+}pi;{-}pi;{0} relative to D;{0}-->K;{-}pi;{+}pi;{0} to be (0.214+/-0.008(stat.)+/-0.008(syst.))%.

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PubMed2006

Observation of a new Ds meson decaying to DK at a mass of 2.86 GeV/c2.

We observe a new D_{s} meson with mass (2856.6+/-1.5_{stat}+/-5.0_{syst}) MeV/c;{2} and width (48+/-7_{stat}+/-10_{syst}) MeV/c;{2} decaying into D0K+ and D;{+}K_{S};{0}. In the same mass distributions, we also observe a broad structure with mass (2688+/-4_{stat}+/-3_{syst}) MeV/c;{2} and width (112+/-7_{stat}+/-36_{syst}) MeV/c;{2}. To obtain this result, we use 240 fb;{-1} of data recorded by the BABAR detector at the PEP-II asymmetric-energy e;{+}e;{-} storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV.

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PubMed2006

Measurement of the B-->pi l nu branching fraction and determination of absolute value of V(ub) with tagged B mesons.

We report a measurement of the B-->pi l nu branching fraction based on 211 fb(-1) of data collected with the BABAR detector. We use samples of B0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B(0)-->pi- l+ nu) = (1.33+/-0.17stat+/-0.11syst) x 10(-4). We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element absolute value V(ub) by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find absolute value V(ub) = (4.5+/-0.5stat+/-0.3syst(+0.7) -0.5FF x 10(-3), where the last error is due to the normalization of the form factor.

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PubMed2006

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 B-->etaK*, where K* indicates a spin 0, 1, or 2 Kpi system. The data sample corresponds to 344x10(6) BB 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): B(B0-->etaK*0(892))=16.5+/-1.1+/-0.8, B(B+-->etaK*+(892))=18.9+/-1.8+/-1.3, B(B0-->eta(Kpi)0*0)=11.0+/-1.6+/-1.5, B(B+-->eta(Kpi)0*+)=18.2+/-2.6+/-2.6, B(B0-->etaK2*0(1430))=9.6+/-1.8+/-1.1, and B(B+-->etaK2*+(1430))=9.1+/-2.7+/-1.4. We also determine the charge asymmetries for all decay modes.

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PubMed2006

Measurements of branching fractions, polarizations, and direct CP-violation asymmetries in B-->rhoK* and B-->f0(980)K* decays.

We report searches for B-meson decays to the charmless final states rhoK* and f0(980)K* with a sample of 232x10(6) BB pairs collected with the BABAR detector at the PEP-II e+e- collider. We measure in units of 10(-6) the following branching fractions, where the first error quoted is statistical and the second systematic, or upper limits are given at the 90% confidence level: B(B+-->rho0K*+)<6.1, B(B+-->rho+K*0)=9.6+/-1.7+/-1.5, B(B0-->rho-K*+)<12.0, B(B0-->rho0K*0)=5.6+/-0.9+/-1.3, B(B+-->f0(980)K*+)=5.2+/-1.2+/-0.5, and B(B0-->f0(980)K*0)<4.3. For the significant modes, we also measure the fraction of longitudinal polarization and the charge asymmetry: fL(B+-->rho+K*0)=0.52+/-0.10+/-0.04, fL(B0-->rho0K*0)=0.57+/-0.09+/-0.08, ACP(B+-->rho+K*0)=-0.01+/-0.16+/-0.02, ACP(B0-->rho0K*0)=0.09+/-0.19+/-0.02, and ACP(B+-->f0(980)K*+)=-0.34+/-0.21+/-0.03.

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PubMed2006

Observation of B+ --> K0K+ and B0 --> K0K0.

We report observations of the b --> d penguin-dominated decays B+ --> K0K+ and B0 --> K0K0 in 316 fb(-1) of e+ e- collision data collected with the BABAR detector. We measure the branching fractions B(B+ --> K0K+) = (1.61+/-0.44+/-0.09) x 10(-6) and B(B0 --> K0K0 = (1.08+/-0.28+/-0.11) x 10(-6) and the CP-violating charge asymmetry A(CP)(K0K+) = 0.10+/-0.26+/-0.03. Using a vertexing technique previously employed in several analyses of all-neutral final states containing kaons, we report the first measurement of time-dependent CP-violating asymmetries in B0 --> K(S)0K(S)0, obtaining S = -1.28(-0.73-0.16)(+0.80+0.11) and C = -0.40+/-0.41+/-0.06. We also report improved measurements of the branching fraction B(B+ --> K0 pi+) = (23.9+/-1.1+/-1.0) x 10(-6) and CP-violating charge asymmetry A(CP)(K0 pi+) = -0.029+/-0.039+/-0.010.

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PubMed2006

Measurement of the branching fraction and photon energy moments of B-->Xs gamma and A(CP)(B --> X(s+d gamma)).

The photon spectrum in B-->Xs gamma decay, where Xs is any strange hadronic state, is studied using a data sample of 88.5 x 10(6) e+ e- --> Upsilon(4S) --> BB decays collected by the BABAR experiment at the Stanford Linear Accelerator Center. The partial branching fraction, DeltaB(B --> Xs gamma) = (3.67+/-0.29(stat)+/-0.34(syst)+/-0.29(model)) x 10(-4), the first moment = 2.288+/-0.025+/-0.017+/-0.015 GeV, and the second moment E2(gamma) = 0.0328+/-0.0040+/-0.0023+/-0.0036 GeV2 are measured for the photon energy range 1.9 GeV < E gamma < 2.7 GeV. They are also measured for narrower E gamma ranges. The moments are then fit to recent theoretical calculations to extract the heavy quark expansion parameters m(b) and mu2(pi) and to extrapolate the partial branching fraction to E gamma > 1.6 GeV. In addition, the direct CP asymmetry A(CP)(B-->X(s+d gamma) is measured to be -0.110+/-0.115(stat)+/-0.017(syst).

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PubMed2006

Observation of e(+)e(-) annihilation into the C = +1 hadronic final states rho(0)rho(0) and phirho(0).

We report the first observation of e(+)e(-) annihilation into states of positive C parity, namely, rho(0)rho(0) and phirho(0). The two states are observed in the pi(+)pi(-)pi(+)pi(-) and K(+)K(-)pi(+)pi(-) final states, respectively, in a data sample of 225 fb(-1) collected by the BABAR experiment at the Positron-Electron Project II e(+)e(-) storage rings at energies near sqrt[s]=10.58 GeV. The distributions of costheta(*), where theta(*) is the center-of-mass polar angle of the phi meson or the forward rho(0) meson, suggest production by two-virtual-photon annihilation. We measure cross sections within the range |costheta(*)|<0.8 of sigma(e(+)e(-)-->rho(0)rho(0))=20.7+/-0.7(stat)+/-2.7(syst) fb and sigma(e(+)e(-)-->phirho(0))=5.7+/-0.5(stat)+/-0.8(syst) fb.

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PubMed2006

Measurement of the spin of the omega(-) hyperon.

A measurement of the spin of the Omega(-) hyperon produced through the exclusive process Xi(c)(0)-->Omega(-)K(+) is presented using a total integrated luminosity of 116 fb(-1) recorded with the BABAR detector at the e(+)e(-) asymmetric-energy B factory at SLAC. Under the assumption that the Xi(c)(0) has spin 1/2, the angular distribution of the Lambda from Omega(-)-->LambdaK(-) decay is inconsistent with all half-integer Omega(-) spin values other than 3/2. Lower statistics data for the process Omega(c)(0)-->Omega(-)pi(+) from a 230 fb(-1) sample are also found to be consistent with Omega(-) spin 3/2. If the Xi(c)(0) spin were 3/2, an Omega(-) spin of 5/2 could not be excluded.

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PubMed2006

Observation of B0 meson decay to a 1 +/(1260)pi /+.

We present a measurement of the branching fraction of the decay B(0)-->a1 (+/)(1260)pi(/+) with a1 (+/)(1260)-->pi(/+)pi(+/)pi(+/). The data sample corresponds to 218 x 10(6) BB[over ] pairs produced in e+e- annihilation through the Upsilon(4S) resonance. We measure the branching fraction Beta(B(0)-->a1(+/)(1260)pi(/+))Beta(a1(+/)(1260)-->pi(/+)pi(+/)pi(+/)) = (16.6+/1.9+/1.5) x 10(-6), where the first error quoted is statistical and the second is systematic.

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PubMed2006

Search for T, CP, and CPT violation in B0-B0 mixing with inclusive dilepton events.

We report the results of a search for T, CP, CPT, and violation in B0-B0 mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II factory. Using a sample of 232 x 10(6) BB pairs, we measure the T and CP violation parameter |q/p| - 1 = (-0.8 +/- 2.7(stat) +/- 1.9(syst) x 10(-3), and the CPT and CP parameters Imz = (13.9 +/- 7.3(stat) +/- 3.2(syst)) x 10(-3) and Delta Gamma x Rez = (7.1 +/- 3.9(stat) +/- 2.0(stat)) x 10(-3) ps(-1). The statistical correlation between the measurements of Imz and Delta Gamma x Rez is 76%.

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PubMed2006

Search for the rare decay B0-->tau+tau- at BABAR.

We present the results of a search for the decay B0-->tau+tau- in a data sample of (232+/-3)x10(6) Upsilon(4S)-->BB decays using the BABAR detector. Certain extensions of the standard model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain Beta(B0->tau+tau-)<4.1x10(-3) at the 90% confidence level.

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PubMed2006

Observation of Upsilon(4S) decays to pi(+)pi(-)Upsilon(1S) and pi(+)pi(-)Upsilon(2S).

Observation of Upsilon(4S) decays to pi(+)pi(-)C and pi(+)pi(-)Upsilon(2S)We present the first measurement of Upsilon(4S) decays to pi(+)pi(-)Upsilon(1S) based on a sample of 230 x 106(4S) mesons collected with the BABAR detector. We measure the product branching fractions Beta(Upsilon(4S) --> pi(+)pi(-)Upsilon(1S)) x BetaUpsilon(1S) --> mu(+)mu(-) = (2.23 +/- 0.25(stat) +/- 0.27(syst))x 10(-6) and Beta(Upsilon(4S) --> pi(+)pi(-)Upsilon(2S) x Beta(Upsilon(2S) --> mu(+)mu(-))=(1.69 +/-0.26(stat) +/- 0.20(syst)) x 10(-)6, from which we derive the partial widths Gamma(Upsilon(4S) --> pi(+)pi(-)Upsilon(1S))=(1.8 +/-0.4) keV and Gamma(Upsilon(4S) --> pi(+)pi(-)Upsilon(2S))=(2.7 +/- 0.8) keV.

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PubMed2006

Determinations of from inclusive semileptonic decays with reduced model dependence.

We report two novel determinations of /|Vub/ with reduced model dependence, based on measurements of the mass distribution of the hadronic system in semileptonic B decays. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson from Upsilon(4S)-->BB events. In one approach, we combine the inclusive B-->Xulambdav rate, integrated up to a maximum hadronic mass mX<1.67 GeV/c2, with a measurement of the inclusive B-->Xsgamma photon energy spectrum. We obtain /Vub/=(4.43+/-0.38stat+/-0.25syst+/-0.29theo) x 10-3. In another approach we measure the total B-->Xulambdav rate over the full phase space and find /Vub/=(3.84+/-0.70stat+/-0.30syst+/-0.10theo) x 10-3.

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PubMed2006

Measurements of the absolute branching fractions of B+/- --> K+/-X(cc).

We study the two-body decays of B+/- mesons to K+/- and a charmonium state X(cc) in a sample of 210.5 fb(-1) of data from the BABAR experiment. We perform measurements of absolute branching fractions beta(B+/- --> K+/-X(cc)) using a missing mass technique, and report several new or improved results. In particular, the upper limit beta(B+/- --> K+/- X(3872)) < 3.2 x 10(-4) at 90% C.L. and the inferred lower limit beta(X(3872)J/psipi+ pi-) > 4.2% will help in understanding the nature of the recently discovered X(3872).

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PubMed2006

Search for lepton flavor violation in the decay tau+/--->e+/-gamma.

A search for the nonconservation of lepton flavor in the decay tau+/--->e+/-gamma has been performed with 2.07x10(8) e+e--->tau+tau- events collected by the BABAR detector at the SLAC PEP II storage ring at a center-of-mass energy near 10.58 GeV. We find no evidence for a signal and set an upper limit on the branching ratio of Beta(tau+/--->e+/-gamma)<1.1x10(-7) at 90% confidence level.

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PubMed2006

Measurement of branching fractions and resonance contributions for B0 --> D0K+pi- and search for B0 --> D0K+pi- decays.

Using 226 x 10(6) gamma(4S) --> BB events collected with the BABAR detector at the PEP-II e+e- storage ring at the Stanford Linear Accelerator Center, we measure the branching fraction for B0 --> D0K+pi-, excluding B0 --> D*-K+, to be beta(B0 --> D0K+pi-) = (88 +/- 15 +/- 9) x 10(-6). We observe B0 --> D0K*(892)0 and B0 --> D2*(2460)-K+ contributions. The ratio of branching fractions beta(B0 --> D*-K+)/beta(B0 --> D*-pi+) = (7.76 +/- 0.34+/-0.29)% is measured separately. The branching fraction for the suppressed mode B0 --> D0K+pi- is beta(B0 --> D0K+pi-) < 19 x 10(-6) at the 90% confidence level.

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PubMed2005

Evidence for B+ --> K0K+ and B0 --> K0K0, and measurement of the branching fraction and search for direct CP violation in B+ --> K0pi+.

We present evidence for the b --> d penguin-dominated decays B+ --> K0K+ and B0 --> K0K0 in 227 x 10(6) Y(4S) --> BB decays collected with the BABAR detector. We measure the branching fractions B(B+ --> K0K+) = (1.5 +/- 0.5 +/- 0.1) x 10(-6)(< 2.4 x 10(-6)) and B(B0 --> K0K0) = [formula: see text], where the uncertainties are statistical and systematic, respectively. We also present improved measurements of the charge-averaged branching fraction B(B+ --> K0pi+) = (26.0 +/- 1.3 +/- 1.0) x 10(-6) and CP-violating charge asymmetry A(CP) (K0pi+) = -0.09 +/- 0.05 +/- 0.01), where the uncertainties are statistical and systematic, respectively.

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