Search results for " ANN"

showing 10 items of 1343 documents

Search forD0→γγand improved measurement of the branching fraction forD0→π0π0

2015

Using 2.92 fb(-1) of electron-positron annihilation data collected at root s = 3.773 GeV with the BESIII detector, we report the results of a search for the flavor-changing neutral current process D-0 -> gamma gamma using a double-tag technique. We find no signal and set an upper limit at 90% confidence level for the branching fraction of B(D-0 -> gamma gamma pi(0)pi(0)) = (8.24 +/- 0.21(stat) +/- 0.30(syst)) x 10(-4), the most precise measurement to date and consistent with the current world average.

PhysicsNuclear and High Energy PhysicsParticle physicsAnnihilationNeutral current010308 nuclear & particles physicsBranching fractionElectron–positron annihilation01 natural sciencesGamma gammaNuclear physics0103 physical sciencesPi010306 general physicsPhysical Review D
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Measurements of cross section of e+e−→pp¯π0 at center-of-mass energies between 4.008 and 4.600 GeV

2017

Based on e(+)e(-) annihilation data samples collected with the BESIII detector at the BEPCII collider at 13 center-of-mass energies from 4.008 to 4.600 GeV, measurements of the Born cross section o ...

PhysicsNuclear and High Energy PhysicsParticle physicsAnnihilationPhysics::Instrumentation and Detectors010308 nuclear & particles physicsPartial wave analysisElectron–positron annihilationHadronDalitz plot01 natural scienceslaw.inventionNuclear physicslaw0103 physical sciencesHigh Energy Physics::ExperimentCenter of massBorn approximation010306 general physicsColliderPhysics Letters B
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Study of the decayDs+→K+K−e+νe

2008

Using 214fb-1 of data recorded by the BABAR detector at the PEPII electron-positron collider, we study the decay Ds+→K+K-e+νe. Except for a small S-wave contribution, the events with K+K- masses in the range 1.01-1.03GeV/c2 correspond to mesons. For Ds+→ e+νe decays, we measure the relative normalization of the Lorentz invariant form factors at q2=0, rV=V(0)/A1(0)=1.849±0.060±0.095, r2=A2(0)/A1(0)=0.763±0. 071±0.065 and the pole mass of the axial-vector form factors mA=(2.28-0.18+0.23±0.18)GeV/c2. Within the same K+K- mass range, we also measure the relative branching fraction B(Ds+→K+K-e+νe)/B(Ds+→K+K- π+)=0.558±0.007±0.016, from which we obtain the total branching fraction B(Ds+→ e+νe)=(2…

PhysicsNuclear and High Energy PhysicsParticle physicsAntiparticleMeson010308 nuclear & particles physicsBranching fractionElectron–positron annihilationHadron01 natural sciencesParticle decayTheoretical physicsPair production0103 physical sciences010306 general physicsDimensionless quantityPhysical Review D
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Constraining Nonstandard Neutrino-Electron Interactions

2007

We present a detailed analysis on nonstandard neutrino interactions (NSI) with electrons including all muon and electron (anti)-neutrino data from existing accelerators and reactors, in conjunction with the ``neutrino counting'' data (e- e+ -> nu nu gamma) from the four LEP collaborations. First we perform a one-parameter-at-a-time analysis, showing how most constraints improve with respect to previous results reported in the literature. We also present more robust results where the NSI parameters are allowed to vary freely in the analysis. We show the importance of combining LEP data with the other experiments in removing degeneracies in the global analysis constraining flavor-conservin…

PhysicsNuclear and High Energy PhysicsParticle physicsAntiparticleMuonElectron–positron annihilationFísicaFOS: Physical sciencesElementary particleMassless particleNuclear physicsParticle decayHigh Energy Physics - PhenomenologyHigh Energy Physics - Phenomenology (hep-ph)High Energy Physics::ExperimentNeutrinoLepton
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Measurement of the branching fraction for ψ(3770) → γχc0

2016

Kolcu, Onur Buğra (Arel Author) --- Makale 70 yazarlıdır.

PhysicsNuclear and High Energy PhysicsParticle physicsBESIII детектор010308 nuclear & particles physicsBranching fractionElectron–positron annihilationMonte Carlo methodDetectorCollision01 natural scienceslcsh:QC1-999NOData setNuclear physicsBEPCII коллайдер0103 physical sciences010306 general physicslcsh:Physics
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Report of the working group on searches

1998

The `Searches' working group discussed a variety of topics relating to present and future measurements of searches at LEP2. The individual contributions are included separately.

PhysicsNuclear and High Energy PhysicsParticle physicsCharginoLuminosity (scattering theory)Group (mathematics)Electron–positron annihilationHiggs bosonLeptoquarkSupersymmetryVariety (universal algebra)Journal of Physics G: Nuclear and Particle Physics
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Vector form factor of the pion from unitarity and analyticity: a model-independent approach

2001

7 páginas, 2 figuras, 3 tablas.-- PACS number(s): 13.35.Dx, 12.39.Fe, 13.40.Gp, 13.65.1i

PhysicsNuclear and High Energy PhysicsParticle physicsChiral perturbation theoryMuonUnitarityAnomalous magnetic dipole momentElectron–positron annihilationNuclear TheoryForm factor (quantum field theory)FOS: Physical sciencesFísicaFine-structure constantHigh Energy Physics - ExperimentHigh Energy Physics - Experiment (hep-ex)High Energy Physics - PhenomenologyPionHigh Energy Physics - Phenomenology (hep-ph)High Energy Physics::ExperimentNuclear Experiment
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MEASUREMENT OF THE PRODUCTION-RATES OF ETA AND ETA' IN HADRONIC-Z DECAYS

1992

The decays eta --> gammagamma and eta' --> etapi+pi- have been observed in hadronic decays of the Z produced at LEP. The fragmentation functions of both the eta and eta' have been measured. The measured multiplicities for x > 0.1 are 0.298 +/- 0.023 +/- 0.021 and 0.068 +/- 0.018 +/- 0.016 for eta and eta' respectively. While the fragmentation function for the eta is fairly well described by the JETSET Monte Carlo, it is found that the production rate of the eta' is a factor of four less than the corresponding prediction.

PhysicsNuclear and High Energy PhysicsParticle physicsE+E ANNIHILATIONElectron–positron annihilationMonte Carlo methodHadronLEPNuclear physicsFragmentation (mass spectrometry)Fragmentation functionHigh Energy Physics::ExperimentAstrophysics::Earth and Planetary AstrophysicsNuclear ExperimentParticle Physics - ExperimentProduction rate
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Next-to-next-to-leading order τ+τ- production cross section close to threshold

2001

13 páginas, 5 figuras.-- PACS number(s): 12.20.Ds, 14.60.Fg

PhysicsNuclear and High Energy PhysicsParticle physicsElectron–positron annihilationFísicaSigmaObservableFermionNuclear physicsCross section (physics)Order (group theory)Production (computer science)Vacuum polarization
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Search forηandη′invisible decays inJ/ψ→ϕηandϕη′

2013

Using a sample of (225.3 +/- 2.8) x 10(6) J/psi decays collected with the BESIII detector at BEPCII, searches for invisible decays of eta and eta ' in J/psi -> phi eta and phi eta ' are performed. Decays of phi -> K+K- are used to tag the eta and eta ' decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be 2.6 x 10(-4) for the ratio B(eta -> invisible)/B(eta ->gamma gamma) and 2.4 x 10(-2) for B(eta '-> invisible)/B(eta '->gamma gamma). These limits may be used to constrain light dark matter particles or spin-1 U bosons. DOI: 10.1103/PhysRevD.87.012009

PhysicsNuclear and High Energy PhysicsParticle physicsElectron–positron annihilationHigh Energy Physics::ExperimentNuclear ExperimentLight dark matterBosonGamma gammaPhysical Review D
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