Search results for "B-factory"

showing 7 items of 87 documents

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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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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Measurements of the Mass and Width of theηcMeson and of anηc(2S)Candidate

2004

The mass m(eta(c)) and total width Gamma(eta(c))(tot) of the eta(c) meson have been measured in two-photon interactions at the SLAC e(+)e(-) asymmetric B Factory with the BABAR detector. With a sample of approximately 2500 reconstructed eta(c)-->K(0)(S)K+/-pi(-/+) decays in 88 fb(-1) of data, the results are m(eta(c))=2982.5+/-1.1(stat)+/-0.9(syst) MeV/c(2) and Gamma(eta(c))(tot)=34.3+/-2.3(stat)+/-0.9(syst) MeV/c(2). 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/c(2) and width of 17.0+/-8.3(stat)+/-2.5(syst) MeV/c(2). This observation is consistent with expectations for the eta(c)(2S) state.

Quantum chromodynamicsPhysicsMeson010308 nuclear & particles physicsAnalytical chemistryGeneral Physics and AstronomyResonance01 natural sciencesB-factoryNuclear physics0103 physical sciencesHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsPhysical Review Letters
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Collins asymmetries in inclusive chargedKKandKπpairs produced ine+e−annihilation

2015

We present measurements of Collins asymmetries in the inclusive process e^+e^− → h_1h_2X, h_1h_2 = KK, Kπ, ππ, at the center-of-mass energy of 10.6 GeV, using a data sample of 468  fb^(−1) collected by the BABAR experiment at the PEP-II B factory at SLAC National Accelerator Center. Considering hadrons in opposite thrust hemispheres of hadronic events, we observe clear azimuthal asymmetries in the ratio of unlike sign to like sign, and unlike sign to all charged h_1h_2 pairs, which increase with hadron energies. The Kπ asymmetries are similar to those measured for the ππ pairs, whereas those measured for high-energy KK pairs are, in general, larger.

QuarkNuclear physicsPhysicsNuclear and High Energy PhysicsParticle physicsAnnihilationElectron–positron annihilationHadronCenter (category theory)BaBar experimentHigh Energy Physics::ExperimentSign (mathematics)B-factoryPhysical Review D
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First Evidence for cos2β>0 and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity

2018

We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B^{0}→D^{(*)}h^{0} with D→K_{S}^{0}π^{+}π^{-} decays, where h^{0}∈{π^{0},η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^{6}BB[over ¯] pairs recorded by the BABAR detector and (772±11)×10^{6}BB[over ¯] p…

QuarkPhysicsParticle physicsUnitarity010308 nuclear & particles physicsElectron–positron annihilationHadronGeneral Physics and AstronomyDalitz plot01 natural sciencesB-factoryKEKB0103 physical sciencesCP violation010306 general physicsPhysical Review Letters
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Measurement of Semileptonic B Decays into Orbitally Excited Charmed Mesons

2009

We present a study of B decays into semileptonic final states containing charged and neutral D-1(2420) and D-2*(2460). The analysis is based on a data sample of 208 fb(-1) collected at the Y(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. With a simultaneous fit to four different decay chains, the semileptonic branching fractions are extracted from measurements of the mass difference Delta m = m(D**) - m(D) distribution. Product branching fractions are determined to be B(B+ -> D(1)(0)l(+)nu(l)) x B(D-1(0) -> D*+pi(-)) = (2.97 +/- 0.17 +/- 0.17) x 10(-3), B(B+ -> D-2*l(+)nu(e)) x B(D-2*(0) -> D(*)+pi(-)) = (2.29 +/- 0.23 +/- 0.21) x 10(-3), B(B-0 -> D…

Semileptonic decayParticle physicsMesonBABARHadronAnalytical chemistryGeneral Physics and AstronomyFOS: Physical sciencesB meson01 natural sciencesPARTICLE PHYSICS; PEP2; BABARHigh Energy Physics - ExperimentParticle decayHigh Energy Physics - Experiment (hep-ex)Pion0103 physical sciencesPEP2[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]B meson010306 general physicsB meson; CP violationPhysics010308 nuclear & particles physicsBranching fractionParticle physicsBABAR detectorHEPB-factoryCP violationBaBarPARTICLE PHYSICSFísica de partículesExperimentsPHYSICAL REVIEW LETTERS
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Search forD0−D¯0mixing using semileptonic decay modes

2004

Based on an 87-fb{sup -1} data set collected by the BABAR detector at the PEP-II asymmetric-energy B Factory, a search for D{sup 0}-D-bar{sup 0} mixing has been made using the semileptonic decay modes D*{sup +}{yields}{pi}{sup +}D{sup 0}, D{sup 0}{yields}K{sup (}*{sup )}e{nu} (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the D{sup 0} decay time and D*{sup +}-D{sup 0} mass difference ({delta}M) distributions. The high-statistics sample of unmixed semileptonic D{sup 0} decays is used to model the {delta}M distribution and time dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the D{sup 0}. A r…

Semileptonic decayPhysicsNuclear and High Energy PhysicsParticle physics010308 nuclear & particles physicsElectron–positron annihilationElectron01 natural sciencesParticle identificationB-factoryDistribution (mathematics)0103 physical sciencesInvariant mass010306 general physicsMixing (physics)Physical Review D
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