Search results for " ANN"

showing 10 items of 1343 documents

Measurement of theB+→ωl+νandB+→ηl+νbranching fractions

2009

We present a study of the charmless semileptonic B-meson decays B{sup +}{yields}{omega}l{sup +}{nu} and B{sup +}{yields}{eta}l{sup +}{nu}. The analysis is based on 3.83x10{sup 8} BB pairs recorded at the {upsilon}(4S) resonance with the BABAR detector. The {omega} mesons are reconstructed in the channel {omega}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0} and the {eta} mesons in the channels {eta}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0} and {eta}{yields}{gamma}{gamma}. We measure the branching fractions B(B{sup +}{yields}{omega}l{sup +}{nu})=(1.14{+-}0.16{sub stat}{+-}0.08{sub syst})x10{sup -4} and B(B{sup +}{yields}{eta}l{sup +}{nu})=(0.31{+-}0.06{sub stat}{+-}0.08{sub syst})x10{sup -4}.

PhysicsSemileptonic decayNuclear and High Energy PhysicsMeson010308 nuclear & particles physicsBranching fractionElectron–positron annihilationBranching (polymer chemistry)01 natural sciencesOmegaCrystallography0103 physical sciencesHigh Energy Physics::ExperimentB mesonNuclear Experiment010306 general physicsPhysical Review D
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Search for the rare decayB→Kνν¯

2010

We present a search for the rare decays B+→K+νν and B0→K0νν using 459×106 BB pairs collected with the BABAR detector at the SLAC National Accelerator Laboratory. Flavor-changing neutral-current decays such as these are forbidden at tree level but can occur through one-loop diagrams in the standard model (SM), with possible contributions from new physics at the same order. The presence of two neutrinos in the final state makes identification of signal events challenging, so reconstruction in the semileptonic decay channels B→D(*)lν of the B meson recoiling from the signal B is used to suppress backgrounds. We set an upper limit at the 90% confidence level (CL) of 1.3×10-5 on the total branch…

PhysicsSemileptonic decayNuclear and High Energy PhysicsParticle physics010308 nuclear & particles physicsBranching fractionElectron–positron annihilationPhysics beyond the Standard Model01 natural sciencesB-factoryNuclear physics0103 physical sciencesB mesonNeutrino010306 general physicsPhysical Review D
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Study of theτ−→3h−2h+ντdecay

2005

The branching fraction of the tau- --> 3h- 2h+ nu decay (h= pi, kaon) is measured with the BaBar detector to be (8.56 +/- 0.05 +/- 0.42)E-04 where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the rho resonance playing a strong role. The decay tau- --> f1 pi nu with the f1 meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9 +/- 0.7 +/- 0.5)E-04.

PhysicsSemileptonic decayNuclear and High Energy PhysicsParticle physicsMeson010308 nuclear & particles physicsBranching fractionElectron–positron annihilationResonance01 natural sciencesParticle identificationNuclear physicsPionPhase space0103 physical sciencesHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsPhysical Review D
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Observation of the Semileptonic DecaysB→D*τ−ν¯τand Evidence forB→Dτ−ν¯τ

2008

We present measurements of the semileptonic decays B--->D0tau-nutau, B--->D*0tau-nutau, B0-->D+tau-nutau, and B0-->D*+tau-nutau, which are potentially sensitive to non-standard model amplitudes. The data sample comprises 232x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector. From a combined fit to B- and B0 channels, we obtain the branching fractions B(B-->Dtau-nutau)=(0.86+/-0.24+/-0.11+/-0.06)% and B(B-->D*tau-nutau)=(1.62+/-0.31+/-0.10+/-0.05)% (normalized for the B0), where the uncertainties are statistical, systematic, and normalization-mode-related.

PhysicsSemileptonic decayNuclear physicsParticle physics010308 nuclear & particles physicsBranching fractionElectron–positron annihilation0103 physical sciencesGeneral Physics and Astronomy010306 general physics01 natural sciencesPhysical Review Letters
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Determinations of|Vub|from Inclusive SemileptonicBDecays with Reduced Model Dependence

2006

We report two novel determinations of |V{sub ub}| 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) {yields} (B{bar B}) events. In one approach, we combine the inclusive {bar B} {yields} X{sub u}{ell}{bar {nu}} rate with a measurement of the inclusive B {yields} X{sub s}{gamma} photon energy spectrum. We obtain |V{sub ub}| = (4.43 {+-} 0.38{sub stat} {+-} 0.25{sub syst} {+-} 0.29{sub theo}) x 10{sup -3}. In another approach we measure the total {bar B} {yields}…

PhysicsSemileptonic decayParticle physicsMass distribution010308 nuclear & particles physicsElectron–positron annihilationHigh Energy Physics::PhenomenologyHadronGeneral Physics and AstronomyPhoton energy7. Clean energy01 natural sciences0103 physical sciencesHigh Energy Physics::ExperimentB meson010306 general physicsBar (unit)LeptonPhysical Review Letters
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Measurement of the absolute branching fraction of the inclusive semileptonic $\Lambda_c^+$ decay

2018

Physical review letters 121(25), 251801 (2018). doi:10.1103/PhysRevLett.121.251801

PhysicsSemileptonic decayParticle physicsMeson010308 nuclear & particles physicsBranching fractionElectron–positron annihilationAstrophysics::High Energy Astrophysical PhenomenaHigh Energy Physics::PhenomenologyGeneral Physics and AstronomyLambda53001 natural sciencesNOLuminosityHigh Energy Physics - ExperimentSubatomär fysikPhysics and Astronomy (all)Subatomic Physics0103 physical sciencesddc:530High Energy Physics::Experiment010306 general physicsEnergy (signal processing)Astrophysics::Galaxy Astrophysics
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Measurement of theB0→π−l+νForm-Factor Shape and Branching Fraction, and Determination of|Vub|with a Loose Neutrino Reconstruction Technique

2007

We report the results of a study of the exclusive charmless semileptonic decay, B-0 ->pi(-)center dot(+)nu, undertaken with approximately 227x10(6) BB pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with an innovative loose neutrino reconstruction technique. We obtain partial branching fractions in 12 bins of q(2), the momentum transfer squared, from which we extract the f(+)(q(2)) form-factor shape and the total branching fraction B(B-0 ->pi(-)l(+)nu)=(1.46 +/- 0.07(stat)+/- 0.08(syst))x10(-4). Based on a recent unquenched lattice QCD calculation of the form factor in the range q(2)> 16 GeV2, we f…

PhysicsSemileptonic decayParticle physicsMeson010308 nuclear & particles physicsBranching fractionElectron–positron annihilationGeneral Physics and AstronomyAstrophysics::Cosmology and Extragalactic Astrophysics01 natural sciencesNuclear physics0103 physical sciencesHigh Energy Physics::ExperimentB mesonNeutrino010306 general physicsDimensionless quantityLeptonPhysical Review Letters
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Measurement of theCPAsymmetry inb→sγUsing a Sum of Exclusive Final States

2008

We perform a measurement of the CP asymmetry in b → sγ decays using a sample of 383×10^6 B[overline]B events collected by the BABAR detector at the SLAC PEP-II asymmetric B factory. We reconstruct 16 flavor-specific B decay modes containing a high-energy photon and a hadronic system X_s containing an s quark. We measure the CP asymmetry to be -0.011±0.030(stat)±0.014(syst) for a hadronic system mass between 0.6 and 2.8 GeV/c^2.

PhysicsStrange quarkParticle physicsPhoton010308 nuclear & particles physicsmedia_common.quotation_subjectElectron–positron annihilationHigh Energy Physics::PhenomenologyHadronGeneral Physics and Astronomy01 natural sciencesAsymmetryB-factoryNuclear physicsParticle decay0103 physical sciencesHigh Energy Physics::ExperimentB mesonNuclear Experiment010306 general physicsmedia_commonPhysical Review Letters
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Determination of the number of J/psi events with J/psi -> inclusive decays

2012

The number of J/psi events collected with the BESIII detector at the BEPC II from June 12 to July 28, 2009 is determined to be (225.3 +/- 2.8) x 10(6) using J/psi -> inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.

PhysicsSystematic errorNuclear and High Energy PhysicsElectron–positron annihilationDetectorMonte Carlo methodBESIIIInclusive eventsAstronomy and AstrophysicsJ/ψ→Nuclear physicsBESIII detector; Inclusive events; J/ψ→; Number of J/ψ eventsNumber of J/ψ eventsJ/psi -> inclusive eventsnumber of J/psi eventsBESIII detectorInstrumentationChinese physics c
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Improved measurement of the CKM angleγinB∓→D(*)K(*)∓decays with a Dalitz plot analysis ofDdecays toKS0π+π−andKS0K+K−

2008

We report on an improved measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase {gamma} through a Dalitz plot analysis of neutral D meson decays to K{sub s}{sup 0}{pi}{sup +}{pi}{sup -} and K{sub s}{sup 0}K{sup +}K{sup -} produced in the processes B{sup {-+}} {yields} DK{sup {-+}}, B{sup {-+}} {yields} D* K{sup {-+}} with D* {yields} D{pi}{sup 0}, D{gamma}, and B{sup {-+}} {yields} DK*{sup {-+}} with K8{sup {-+}} {yields} K{sub S}{sup 0}{pi}{sup {-+}}. Using a sample of 383 million B{bar B} pairs collected by the BABAR detector, we measure {gamma} = (76 {+-} 22 {+-} 5{+-} 5){sup o} (mod 180{sup o}), where the first error is statistical, the second is the experimental systematic unc…

PhysicsSystematic errorNuclear and High Energy PhysicsParticle physics010308 nuclear & particles physicsElectron–positron annihilationDalitz plot01 natural sciencesCrystallographyParticle decayTheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY0103 physical sciencesD mesonPiCP violation010306 general physicsBar (unit)Physical Review D
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