0000000000082526

AUTHOR

Achille Stocchi

showing 35 related works from this author

Erratum: Measurement of the absolute branching fractions forDs−→ℓ−ν¯ℓand extraction of the decay constantfDs[Phys. Rev. D82, 091103(R) (2010)]

2015

Nuclear physicsGravitationPhysicsNuclear and High Energy PhysicsQuantum mechanicsExponential decayBranching (polymer chemistry)CosmologyIonPhysical Review D
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Identified particles in quark and gluon jets

1997

A sample of about 1.4 million hadronic Z decays, selected among the data recorded by the DELPHI detector at LEP during 1994, was used to measure for the first time the momentum spectra of K+, K-0, p, Lambda and their antiparticles in gluon and quark jets. As observed for inclusive charged particles, the production spectra of identified particles were found to be softer in gluon jets than in quark jets, with a higher total multiplicity. (C) 1997 Published by Elsevier Science B.V.

QuarkNuclear and High Energy PhysicsParticle physicsAntiparticleElectron–positron annihilationAstrophysics::High Energy Astrophysical PhenomenaHigh Energy Physics::LatticeHadronNuclear Theory01 natural sciencesPartícules (Física nuclear)Nuclear physicsPHYSICSMONTE-CARLO0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]010306 general physicsDetectors de radiacióDELPHIQuantum chromodynamicsPhysics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyAVERAGE MULTIPLICITIES; MONTE-CARLO; QCD; PHYSICSQCDLARGE ELECTRON POSITRON COLLIDERPhoton structure functionCharged particleGluonPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIPARTICLE PHYSICSHigh Energy Physics::ExperimentParticle Physics - ExperimentAVERAGE MULTIPLICITIES
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Measurement of the forward-backward asymmetry of e(+)e(-)-]z-]b(b)over-bar using prompt leptons and a lifetime tag

1995

The forward-backward asymmetry of the process e+e-→Z→b {Mathematical expression} has been measured using events collected by the DELPHI experiment during the 1991 and 1992 LEP runs. This data sample corresponded to 884 000 hadronic Z decays at a centre-of-mass energy {Mathematical expression}. The tagging of b-quark events was performed using two approaches; the first was based on the semileptonic decay channels b→X+μ and b→X+e, the second used a lifetime tag with jet-charge reconstruction. The results of these two methods were combined to give {Mathematical expression} With the semileptonic sample, the forward-backward asymmetry of the process e+e-→Z→ {Mathematical expression} was also mea…

Semileptonic decayParticle physicsFERMION PAIR PRODUCTIONPhysics and Astronomy (miscellaneous)LUND MONTE-CARLOENERGIESElectron–positron annihilationQED CORRECTIONSD-MESONSEMILEPTONIC DECAY01 natural sciencesJET FRAGMENTATIONb-taggingPartícules (Física nuclear)PHYSICSNuclear physics0103 physical sciencesDELPHI; forward-backward asymmetry; b-tagging; jet reconstructionFERMION PAIR PRODUCTION; LUND MONTE-CARLO; E+E-ANNIHILATION; SEMILEPTONIC DECAY; JET FRAGMENTATION; QED CORRECTIONS; FINAL-STATES; D-MESON; ENERGIES; PHYSICS010306 general physicsEngineering (miscellaneous)jet reconstructionDetectors de radiacióDELPHIPhysics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyWeinberg angleE+E-ANNIHILATIONLARGE ELECTRON POSITRON COLLIDERFINAL-STATESb-taggingPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHILarge Electron–Positron ColliderPARTICLE PHYSICSHigh Energy Physics::Experimentforward-backward asymmetryEnergy (signal processing)Particle Physics - ExperimentLeptonBar (unit)
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Exclusive measurements of b → sγ transition rate and photon energy spectrum

2012

We use 429  fb^(-1) of e^+e^- collision data collected at the Υ(4S) resonance with the BABAR detector to measure the radiative transition rate of b→sγ with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be B(B → X_sγ)=(3.29±0.19±0.48)×10+(-4) where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best-fit values for the heavy-quark parameters, m_b and μ_π^2, in the kinetic and shape function models.

PhysicsNuclear and High Energy PhysicsParticle physicsPhoton010308 nuclear & particles physicsBranching fractionElectron–positron annihilationPhoton energyKinetic energyTransition rate matrix01 natural sciencesMeasure (mathematics)Resonance (particle physics)Nuclear physics0103 physical sciencesHigh Energy Physics::Experiment010306 general physics
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PRODUCTION CHARACTERISTICS OF K-0 AND LIGHT MESON RESONANCES IN HADRONIC DECAYS OF THE Z(0)

1995

An analysis of inclusive production of K0and the meson resonances K*±(892), ρ0(770), f0(975) and f2(1270) in hadronic decays of the Z0is presented, based on about 973,000 multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. Overall multiplicities have been determined as 1.962±0.060 K0mesons, 0.712±0.067 K*±(892) and 1.21±0.15ρ0(770) per hadronic Z0decay. The average multiplicities of f0(975) for scaled momentum, xp, in the range 0.05≤xp≤0.6 and of f2(1270) for 0.05≤xp≤1.0 are 0.098±0.016 and 0.170±0.043 respectively. The f0(975) and ρ0(770)xp-spectra have similar shapes. The f2(1270)/ρ0(770) ratio increases with xp. The average multiplicities…

Particle physicsMesonPhysics and Astronomy (miscellaneous)LUND MONTE-CARLOElectron–positron annihilationHadron01 natural sciencesJET FRAGMENTATION250 GEV/CPartícules (Física nuclear)Nuclear physics0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]multiplicityENERGY REGION010306 general physicsParton showerEngineering (miscellaneous)Detectors de radiacióDELPHI. inclusive production; K0 meson; multiplicity; MontecarloPhysicsRange (particle radiation)Momentum (technical analysis)010308 nuclear & particles physicsMultiplicity (mathematics)E+E-ANNIHILATIONINCLUSIVE PRODUCTIONZ0 DECAYSMontecarloParticle accelerationLUND MONTE-CARLO; E+E-ANNIHILATION; INCLUSIVE PRODUCTION; JET FRAGMENTATION; Z0 DECAYS; P INTERACTIONS; VECTOR-MESONS; ENERGY REGION; 250 GEV/C; 360 GEV/C360 GEV/CP INTERACTIONSK0 mesonDELPHI. inclusive productionVECTOR-MESONSParticle Physics - Experiment
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FIRST MEASUREMENT OF THE STRANGE QUARK ASYMMETRY AT THE Z(0) PEAK

1995

A measurement of the strange quark forward-backward asymmetry at the Z0 peak was performed using 718,000 multihadronic Z0 decays collected by the DELPHI detector at LEP in 1992. The s-quark was tagged by the presence of high momentum charged kaons identified by the Ring Imaging Cherenkov detector and by Λ0;s decaying into pπ-. The s-quark purity obtained was estimated for the two hadrons to be 43%. The average s-quark asymmetry was found to be 0.131±0.035 (stat.) ±0.013 (syst.). The forward-backward asymmetry was measured for unresolved d-and s-quarks, tagged by the detection of a high energy neutron or neutral kaon in the Hadron Calorimeter. The combined d-and s-quark purity was 69% and th…

Strange quarkParticle physicsPhysics and Astronomy (miscellaneous)s-quarkLUND MONTE-CARLOHigh Energy Physics::LatticeElectron–positron annihilationmedia_common.quotation_subjectHadronNuclear TheoryLUND MONTE-CARLO; CHARGE ASYMMETRY; HADRONIC DECAYS; Z0; ANNIHILATION; EVENTS; JETSLambda01 natural sciencesAsymmetryRing-imaging Cherenkov detectorPartícules (Física nuclear)EVENTSNuclear physics0103 physical sciencesDELPHI; asymmetry; Z0 resonance; s-quark[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]NeutronZ0ANNIHILATION010306 general physicsNuclear ExperimentCHARGE ASYMMETRYEngineering (miscellaneous)DELPHImedia_commonPhysics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyWeinberg angleLARGE ELECTRON POSITRON COLLIDERZ0 resonancePARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIJETSPARTICLE PHYSICSHigh Energy Physics::ExperimentCol·lisionadors d'hadronsHADRONIC DECAYSasymmetryParticle Physics - Experiment
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Search forCPviolation in the decayD±→KS0π±

2011

We report on a search for CP violation in the decay D{sup {+-}} {yields} K{sub S}{sup 0}{pi}{sup {+-}} using a data set corresponding to an integrated luminosity of 469 fb{sup -1} collected with the BABAR detector at the PEP-II asymmetric energy e{sup +}e{sup -} storage rings. The CP-violating decay rate asymmetry A{sub CP} is determined to be (-0.44 {+-} 0.13(stat) {+-} 0.10(syst))%, consistent with zero at 2.7 {sigma} and with the standard model prediction of (-0.332 {+-} 0.006)%. This is currently the most precise measurement of this parameter.

PhysicsNuclear and High Energy PhysicsAntiparticleParticle physicsMeson010308 nuclear & particles physicsHadron01 natural sciencesNuclear physicsParticle decayPion0103 physical sciencesCP violation010306 general physicsEnergy (signal processing)LeptonPhysical Review D
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Measurements of the tau polarisation in Z0 decays

1995

A sample of Z0→τ+τ- events observed in the DELPHI detector at LEP in 1991 and 1992 is analysed to measure the τ polarisation in the exclusive decay channels {Mathematical expression}, {Mathematical expression}, πν, ρν and a1ν. The τ polarisation is also measured with an inclusive hadronic analysis which benefits from a higher efficiency and a better systematic precision than the use of the exclusive decay modes. The results have been combined with those published on the 1990 data. A measurement of the τ polarisation as a function of production angle yields the values for the mean τ polarisation 〈P〉τ=-0.148±0.022 and for the Z0 polarisation PZ=-0.136±0.027. These results are used to determin…

Particle physicsPOLARIZATIONPhysics and Astronomy (miscellaneous)LUND MONTE-CARLOElectron–positron annihilationHadronLEP-SLC ENERGIESElectron01 natural sciencesPartícules (Física nuclear)JET FRAGMENTATIONPARAMETERSNuclear physicsPHYSICSBHABHA SCATTERINGZ-RESONANCE0103 physical sciencesradiative correction[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]RADIATIVE-CORRECTIONS010306 general physicsEngineering (miscellaneous)Detectors de radiacióBhabha scatteringDELPHIPhysics010308 nuclear & particles physicsDetectortau polarizationPolarization (waves)LARGE ELECTRON POSITRON COLLIDERUniversality (dynamical systems)Z resonanceLUND MONTE-CARLO; LEP-SLC ENERGIES; RADIATIVE-CORRECTIONS; BHABHA SCATTERING; JET FRAGMENTATION; Z-RESONANCE; POLARIZATION; PHYSICS; SIMULATION; PARAMETERSSIMULATIONPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIPARTICLE PHYSICSHigh Energy Physics::ExperimentDELPHI; tau polarization; radiative correction; Z resonanceParticle Physics - ExperimentLepton
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Measurement of inclusive production of light meson resonances in hadronic decays of the Z0

1993

A study of inclusive production of the meson resonances ρ0, K*0 (892), f{hook}0 (975) and f{hook}2 (1270) in hadronic decays of the Z0 is presented. The measured mean meson multiplicity per hadronic event is 0.83 ± 0.14 for the ρ0 0.64 ± 0.24 for the K*0 (892), 0.10 ± 0.04 for the f{hook}0 (975) in the momentum range p > 0.05pbeam (xp > 0.05) and 0.11 ± 0.05 for the f{hook}2 (1270) for xp > 0.1. These values and the corresponding differential cross sections ( 1 σhadr) dσ dxp for the vector mesons are in good agreement with the predictions of the JETSET 7.3 PS and HERWIG 5.4 models. The f{hook}2 (1270) production is overestimated by HERWIG but its xp-shape is correctly reproduced. T…

PhysicsNuclear and High Energy PhysicsParticle physicsMesonLUND MONTE-CARLO010308 nuclear & particles physicsElectron–positron annihilationHadronE+E-ANNIHILATION01 natural sciencesJET FRAGMENTATIONK+P INTERACTIONSPHYSICSNuclear physicsGEV/C0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]RHO0Física nuclearMultiplicity (chemistry)010306 general physicsParticle Physics - ExperimentLUND MONTE-CARLO; E+E-ANNIHILATION; K+P INTERACTIONS; JET FRAGMENTATION; PHYSICS; GEV/C; RHO0Physics Letters B
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Observation of the decayB¯0→Λc+p¯π0

2010

In a sample of 467 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II collider at SLAC we have observed the decay (B) over bar (0) -> Lambda(+)(c)(p) over bar pi(0) and measured the branching fraction to be (1.94 +/- 0.17 +/- 0.14 +/- 0.50 x 10(-4), where the uncertainties are statistical, systematic, and the uncertainty on the Lambda(+)(c) -> pK(-)pi(+) branching fraction, respectively. We determine an upper limit of 1.5 x 10(-6) at 90% C.L. for the product branching fraction B((B) over bar (0) -> Sigma(+)(c) (2455)(p) over bar) x B(Lambda(+)(c) -> pK(-) pi(+)). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon- antibaryo…

PhysicsNuclear and High Energy Physics010308 nuclear & particles physicsBranching fractionElectron–positron annihilationAnalytical chemistryLambda01 natural sciencesCharmed baryonsParticle decayPion0103 physical sciencesB mesonAtomic physics010306 general physicsBar (unit)Physical Review D
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Evidence for the decayB0→ωωand search forB0→ωϕ

2014

We describe searches for B meson decays to the charmless vector-vector final states ωω and ωϕ with 471 × 10^6B¯B pairs produced in e^+e^− annihilation at √s = 10.58 GeV using the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction β(B^0 → ωω) = (1.2 ± 0.3^(+0.3)_(-0.2) × 10^(−6), where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit β(B^0 → ωω) < 0.7 × 10^(−6) at 90% confidence level. These measurements provide the first evidence for the decay B^0 → ωω, and an improvement of the upper limit for the decay B^0 → ωϕ.

PhysicsNuclear physicsNuclear and High Energy PhysicsParticle physicsAnnihilation010308 nuclear & particles physicsBranching fraction0103 physical sciencesHigh Energy Physics::ExperimentB mesonSupersymmetry010306 general physics01 natural sciencesPhysical Review D
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Search for promptly produced heavy quarkonium states in hadronic Z decays

1996

A search has been made for direct production of heavy quarkonium states in more than 3 million hadronic Z^{0} decays in the 1991-1994 DELPHI data. Prompt J/\psi, \psi(2S) and \Upsilon candidates have been searched for through their leptonic decay modes using criteria based on the kinematics and decay vertex positions. New upper limits are set at the 90 \% confidence level for {Br( Z^0 \rightarrow \left( Q \bar{Q} \right) X ) / Br( Z^0 \rightarrow \mbox{hadrons})} for various strong production mechanisms of J/\psi and \Upsilon; these range down to 0.9 \times 10^{-4}. The limits are set in the presence of a small excess (\sim 1 \% statistical probability of a background fluctuation) in the su…

Systematic errorParticle physicsE+E ANNIHILATIONPhysics and Astronomy (miscellaneous)LUND MONTE-CARLOquarkonium stateHadron01 natural sciencesPartícules (Física nuclear)JET FRAGMENTATIONPHYSICSDirect production0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]010306 general physicsLUND MONTE-CARLO; JET FRAGMENTATION; E+E ANNIHILATION; PHYSICSDELPHIPhysics010308 nuclear & particles physicsBranching fractionHigh Energy Physics::PhenomenologyQuarkoniumLARGE ELECTRON POSITRON COLLIDERDELPHI; quarkonium state; branching ratioVertex (geometry)PARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHILarge Electron–Positron ColliderDecay lengthPARTICLE PHYSICSFísica nuclearHigh Energy Physics::Experimentbranching ratioParticle Physics - Experiment
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A search for invisible Higgs bosons produced in e+e- interactions at LEP 2 energies

1999

Searches for HZ production with the Higgs boson decaying into an invisible final state have been performed with the data collected by the DELPHI experiment up to the centre-of-mass energy of 183 GeV. The hadronic and muon pair final states of the Z boson were analysed. From the absence of signal, upper limits on the cross-section and the corresponding Higgs boson mass limits were set at 95% confidence level. The results are interpreted as excluded parameter regions in the framework of the minimal supersymmetric standard model and in the simplest Majoron model with one Higgs doublet and one Higgs singlet field. (C) 1999 Elsevier Science B.V. All rights reserved.

Nuclear and High Energy PhysicsParticle physicsCOLLISIONSVIOLATIONSTANDARD MODELMASS01 natural sciencesDECAYSPartícules (Física nuclear)Standard ModelNuclear physicsPHYSICSsymbols.namesakeMONTE-CARLO0103 physical sciencesPROGRAM[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]STANDARD MODEL; MONTE-CARLO; PHYSICS; DECAYS; PROGRAM; SUPERSYMMETRY; COLLISIONS; VIOLATION; PARTICLE; MASS010306 general physicsSUPERSYMMETRYBosonMajoronDELPHIPhysics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologySupersymmetryLARGE ELECTRON POSITRON COLLIDERHiggs fieldPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIsymbolsHiggs bosonPARTICLE PHYSICSFísica nuclearHigh Energy Physics::ExperimentPARTICLEHiggs mechanismParticle Physics - ExperimentMinimal Supersymmetric Standard Model
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Strange baryon production in Z hadronic decays

1995

A study of the production of strange octet and decuplet baryons in hadronic decays of the Z recorded by the DELPHI detector at LEP is presented. This includes the first measurement of the ∑± average multiplicity. The total and differential cross sections, the event topology and the baryon-antibaryon correlations are compared with current hadronization models. © 1995 Springer-Verlag.

Particle physicsPhysics and Astronomy (miscellaneous)OctetLUND MONTE-CARLO; JETS; Z(0)LUND MONTE-CARLOElectron–positron annihilationHadronNuclear TheoryElementary particle01 natural sciencesPartícules (Física nuclear)Nuclear physics0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]Quantum field theoryMultiplicity (chemistry)010306 general physicsNuclear ExperimentEngineering (miscellaneous)hadronic decayDELPHIPhysicsbaryon-anti-baryon correlation010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyZ(0)DELPHI; hadronic decay; baryon-anti-baryon correlationLARGE ELECTRON POSITRON COLLIDERHadronizationBaryonPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIJETSPARTICLE PHYSICSFísica nuclearHigh Energy Physics::ExperimentParticle Physics - Experiment
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Masses, lifetimes and production rates of Ξ− and Ξ¯+ at LEP 1

2006

Measurements of the Xi(-) and (Xi) over bar (+) masses, mass differences, lifetimes and lifetime differences are presented. The (Xi) over bar (+) sample used is much larger than those used previously for such measurements. In addition, the S production rates in Z -> b (b) over bar and Z -> q (q) over bar events are compared and the position xi* of the maximum of the distribution in Z -> q (q) over bar events is measured.

PhysicsNuclear physicsNuclear and High Energy Physics010308 nuclear & particles physicsElectron–positron annihilation0103 physical sciencesProduction (computer science)010306 general physics01 natural sciencesBar (unit)Xi baryonPhysics Letters B
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Amplitude analysis of the decayD0→K−K+π0

2007

Using 385 fb^-1 of e^+e^- collisions at the CM energies of around 10.6 GeV recorded by the BaBar experiment, we study the amplitudes of the singly Cabibbo-suppressed decay D^0 --> K^- K^+ pi^0. We measure the strong phase difference between the D0bar and D0 decays to the K^*(892)^+ K^- state to be -35.5 +/- 1.9 (stat) +/- 2.2 (syst) degrees, and their amplitude ratio to be 0.599 +/- 0.013 (stat) +/- 0.011 (syst). We observe significant contributions from the Kpi and K^-K^+ scalar and vector amplitudes, and analyze the moments of the cosine of the helicity angle in these systems. We find no evidence for charged, scalar kappa(800) state, nor for higher spin states. We also perform a model-ind…

PhysicsNuclear and High Energy PhysicsParticle physicsSpin states010308 nuclear & particles physicsElectron–positron annihilationPartial wave analysisScalar (mathematics)BaBar experimentDalitz plot01 natural sciencesHelicityNuclear physicsAmplitude0103 physical sciencesHigh Energy Physics::Experiment010306 general physicsPhysical Review D
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Measurement of the Λb0 decay form factor

2004

The form factor of Λb0 baryons is estimated using 3.46×106 hadronic Z decays collected by the DELPHI experiment between 1992 and 1995. Charmed Λc+ baryons fully reconstructed in the pK-π+, pK S0, and Λπ+π+π - modes, are associated to a lepton with opposite charge in order to select Λb0→Λc+l-ν̄l decays. From a combined likelihood and event rate fit to the distribution of the Isgur-Wise variable w, and using the Heavy Quark Effective Theory (HQET), the slope of the b-baryon form factor is measured to be ρ̂2=2.03±0.46(stat) -1.00+0.72(syst). The exclusive semileptonic branching fraction Br(Λb0→Λc+l-ν̄l) can be derived from ρ̂2 and is found to be (5.0-0.8+1.1(stat)-1.2+1.6(syst))%. Limits on ot…

Semileptonic decayPhysicsParticle physicsNuclear and High Energy Physics010308 nuclear & particles physicsBranching fractionElectron–positron annihilationHadronLambdaLambda baryon01 natural sciencesNuclear physicsBaryon0103 physical sciences010306 general physicsLepton
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Search for charged lepton flavor violation in narrow Y decays

2010

Charged-lepton flavor-violating processes are unobservable in the standard model, but they are predicted to be enhanced in several extensions to the standard model, including supersymmetry and models with leptoquarks or compositeness. We present a search for such processes in a sample of 99 × 10 6 Υ ( 2 S ) decays and 117 × 10 6 Υ ( 3 S ) decays collected with the BABAR detector. We place upper limits on the branching fractions B ( Υ ( n S ) → e ± τ ∓ ) and B ( Υ ( n S ) → μ ± τ ∓ ) ( n = 2 , 3 ) at the 10 − 6 level and use these results to place lower limits of order 1 TeV on the mass scale of charged-lepton flavor-violating effective operators.

Particle physicsPACS: 13.20.Gd 11.30.Hv 14.40.NdPhysics beyond the Standard ModelBABARGeneral Physics and AstronomyElementary particle01 natural sciencesPARTICLE PHYSICS; PEP2; BABARParticle identificationParticle decay0103 physical sciencesPEP2Grand Unified Theory010306 general physicsPhysics010308 nuclear & particles physicsBranching fractionHigh Energy Physics::PhenomenologySupersymmetryBABAR detectorHEPPARTICLE PHYSICSHigh Energy Physics::ExperimentFísica de partículesExperimentsLepton
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Search forB0meson decays toπ0KS0KS0,ηKS0KS0, andη′KS0KS0

2009

We describe searches for B{sup 0} meson decays to the charmless final states {pi}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0}, {eta}K{sub S}{sup 0}K{sub S}{sup 0}, and {eta}{prime}K{sub S}{sup 0}K{sub S}{sup 0}. The data sample corresponds to 467 x 10{sup 6} B{bar B} pairs produced in e{sup +}e{sup -} annihilation and collected with the BABAR detector at the SLAC National Accelerator Laboratory. We find no significant signals and determine the 90% confidence level upper limits on the branching fractions, in units of 10{sup -7}, {Beta}(B{sup 0} {yields} {pi}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0}) < 12, {Beta}(B{sup 0} {yields} {eta}K{sub S}{sup 0}K{sub S}{sup 0}) < 10, and {Beta}(B{sup 0} {yields} {…

PhysicsNuclear and High Energy PhysicsAnnihilationMeson010308 nuclear & particles physicsBranching fractionElectron–positron annihilation01 natural sciencesParticle decayCrystallographyTheoretical physicsPair productionTheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY0103 physical sciencesCP violationB meson010306 general physicsPhysical Review D
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PRODUCTION-RATE AND DECAY LIFETIME MEASUREMENTS OF B(S)0 MESONS AT LEP USING D(S) AND PHI MESONS

1994

The study of the properties of inclusive production of Ds mesons and of events in which a φ{symbol} and a muon are present in the same jet provides two independent measurements of the probability, fs w, for a heavy quark to hadronize into a strange B or D meson. The data sample analysed corresponds to 243,000 hadronic Z0 decays. The combined value of these measurements is fs w=0.19±0.06±0.08. From the flight distance distributions of Ds and of (φ{symbol}-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, two values are obtained for the Bs 0 meson lifetime. Combining these measurements with a previous result based on the study of Ds-μ ev…

QuarkParticle physicsPhysics and Astronomy (miscellaneous)MesonLUND MONTE-CARLOElectron–positron annihilationNuclear TheoryJet (particle physics)01 natural sciencesJET FRAGMENTATIONNuclear physicsPHYSICS0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]B mesonZ0010306 general physicsNuclear ExperimentEngineering (miscellaneous)PhysicsMuonB-MESONS010308 nuclear & particles physicsPhysicsHigh Energy Physics::PhenomenologyLUND MONTE-CARLO; JET FRAGMENTATION; B-MESONS; PHYSICS; Z0High Energy Physics::ExperimentFísica nuclearParticle Physics - ExperimentProduction rateLepton
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Search for resonances decaying toηcπ+π−in two-photon interactions

2012

We report a study of the process gamma gamma -> X -> eta_c pi+ pi-, where X stands for one of the resonances chi_{c2}(1P), eta_c(2S), X(3872), X(3915), or chi_{c2}(2P). The analysis is performed with a data sample of 473.9 fb^{-1} collected with the BaBar detector at the PEP-II asymmetric-energy electron-positron collider. We do not observe a significant signal for any channel, and calculate 90% confidence-level upper limits on the products of branching fractions and two-photon widths Gamma(X -> gamma gamma)BR(X -> eta_c pi+ pi-): 15.7 eV for chi_{c2}(1P), 133 eV for eta_c(2S), 11.1 eV for X(3872) (assuming it to be a spin-2 state), 16 eV for X(3915) (assuming it to be a spin-2 state), and …

PhysicsNuclear physicsNuclear and High Energy Physics010308 nuclear & particles physics0103 physical sciencesAnalytical chemistryPiResonance010306 general physics01 natural sciencesX(3872)Gamma gammaPhysical Review D
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A measurement of the branching fractions of the b quark into charged and neutral b hadrons

2003

The production fractions of charged and neutral b-hadrons in b-quark events from Z0 decays have been measured with the DELPHI detector at LEP. An algorithm has been developed, based on a neural network, to estimate the charge of the weakly-decaying b-hadron by distinguishing its decay products from particles produced at the primary vertex. From the data taken in the years 1994 and 1995, the fraction of bbar-quarks fragmenting into positively charged weakly-decaying b-hadrons has been measured to be: f^+ = (42.09 +/- 0.82 (stat.) +/- 0.89 (syst.))%. Subtracting the rates for charged Xibar_b^+ and Omegabar_b^+ baryons gives the production fraction of B^+ mesons: f_Bu = (40.99 +/- 0.82 (stat.)…

QuarkParticle physicsNuclear and High Energy PhysicsMesonElectron–positron annihilationHadronNuclear TheoryFOS: Physical sciencesLIFETIMEBranching (polymer chemistry)01 natural sciencesBottom quarkOmegaHigh Energy Physics - ExperimentNuclear physicsHigh Energy Physics - Experiment (hep-ex)0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]010306 general physicsNuclear ExperimentZ-DECAYSDELPHIPhysicsBARYONS010308 nuclear & particles physicsPhysicsHigh Energy Physics::PhenomenologyLEPMESONSLARGE ELECTRON POSITRON COLLIDERBaryonPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIZ-DECAYS; LIFETIME; BARYONS; MESONS; LEPPARTICLE PHYSICSHigh Energy Physics::ExperimentParticle Physics - Experiment
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Precision Measurement of theB→XsγPhoton Energy Spectrum, Branching Fraction, and DirectCPAsymmetryACP(B→Xs+dγ)

2012

The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B → X_sγ plus B → X_dγ, is studied using a data sample of (382.8±4.2)×10^6Υ(4S) → BB decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B → X_sγ)=(3.21±0.33)×10^(-4) for E_γ > 1.8  GeV and the direct CP asymmetry A_(CP)(B → X_(s+d)γ)=0.057±0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.

PhysicsParticle physicsPhoton010308 nuclear & particles physicsBranching fractionmedia_common.quotation_subjectElectron–positron annihilationGeneral Physics and AstronomyBaBar experimentRest framePhoton energy01 natural sciencesAsymmetryNuclear physics0103 physical sciencesB meson010306 general physicsmedia_commonPhysical Review Letters
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Measurement of $\Delta^{++}$(1232) production in hadronic Z decays

1995

A measurement of the \Delta^{++}(1232) inclusive production in hadronic decays of the Z at LEP is presented, based on 1.3 million hadronic events collected~ by the DELPHI~ detector in the 1994 LEP running~ period. The DELPHI ring imaging Cherenkov counters are used for identifying hadrons. The average \Delta^{++}(1232) multiplicity per hadronic event is 0.079 \pm 0.015 which is more than a factor of two below the JETSET, HERWIG and UCLA model predictions. It agrees with a recently proposed universal mass dependence of particle production rates in e^{+}e^- annihilations.

Hadronic decayNuclear and High Energy PhysicsParticle physicsE+E ANNIHILATIONSe+e- annihilationCherenkov detectorElectron–positron annihilationDELPHI; hadronic decay; Cherenkov detector; e+e- annihilationHadron01 natural sciencesPartícules (Física nuclear)law.inventionNuclear physicslaw0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]Multiplicity (chemistry)010306 general physicsCherenkov radiationhadronic decayDELPHIPhysics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyLARGE ELECTRON POSITRON COLLIDERPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIPARTICLE PHYSICSFísica nuclearHigh Energy Physics::ExperimentParticle Physics - ExperimentCherenkov detector
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Measurement of correlations between pions from different W's in e+e- → W+W- events

1997

Correlations between pions from different W's in e(+)e(-) --> W+W- events are studied using data collected by the DELPHI detector at LEP running at a centre-of-mass energy of 172 GeV in 1996. At the present level of statistics, no enhancement of the correlation function above that expected from a pair of uncorrelated W's is observed at small values of the four-momentum difference of the pions. (C) 1997 Published by Elsevier Science B.V.

Nuclear and High Energy PhysicsParticle physicsLUND MONTE-CARLOElectron–positron annihilationBOSE-EINSTEIN CORRELATIONS; LUND MONTE-CARLO; JET FRAGMENTATION; PHYSICS; INTERFEROMETRY; DECAYS; Z(0); Z001 natural sciencesJET FRAGMENTATIONDECAYSPartícules (Física nuclear)Nuclear physicsPHYSICSINTERFEROMETRYPionCorrelation function0103 physical sciencesZ0010306 general physicsNuclear ExperimentDELPHIPhysics010308 nuclear & particles physicsAcceleradors de partículesBose–Einstein correlationsZ(0)LARGE ELECTRON POSITRON COLLIDERUncorrelatedBOSE-EINSTEIN CORRELATIONSLarge Electron–Positron ColliderPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHIPARTICLE PHYSICSHigh Energy Physics::Experiment
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Study ofB→πℓνandB→ρℓνdecays and determination of|Vub|

2005

We present an analysis of exclusive charmless semileptonic B-meson decays based on 83x10{sup 6} BB pairs recorded with the BABAR detector at the {upsilon}(4S) resonance. Using isospin symmetry, we measure branching fractions B(B{sup 0}{yields}{pi}{sup -}l{sup +}{nu})=(1.38{+-}0.10{+-}0.16{+-}0.08)x10{sup -4} and B(B{sup 0}{yields}{rho}{sup -}l{sup +}{nu})=(2.14{+-}0.21{+-}0.48{+-}0.28)x10{sup -4}, where the errors are statistical, experimental systematic, and due to form-factor shape uncertainties. We compare the measured distribution in q{sup 2}, the momentum-transfer squared, with theoretical predictions for the form factors from lattice QCD and light-cone sum rules, and extract the Cabib…

Quantum chromodynamicsPhysicsSemileptonic decayNuclear and High Energy Physics010308 nuclear & particles physicsBranching fractionLattice field theoryLattice QCD01 natural sciencesParticle identificationCrystallographyPionIsospin0103 physical sciences010306 general physicsPhysical Review D
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Study of the baryonicBdecayB−→Σc++p¯π−π−

2012

We report the measurement of the baryonic B decay B- -> SigmaC++ p- pi- pi-. Using a data sample of 467*10^6 B B-bar pairs collected with the BaBar detector at the PEP-II storage ring at SLAC, the measured branching fraction is (2.98 +/- 0.16 (stat) +/- 0.15 (syst) +/- 0.77 (LambdaC+))*10^{-4}, where the last error is due to the uncertainty in the branching fraction of the decay LambdaC+ -> p+ K- pi+. The data suggest the existence of resonant subchannels B- -> LambdaC(2595)+ p- pi- and, possibly, B- -> SigmaC++ anti-Delta-- pi-. We see unexplained structures in m(SigmaC++ pi- pi-) at 3.25 GeV/c^2, 3.8 GeV/c^2, and 4.2 GeV/c^2.

PhysicsBaryonCharmed baryonsNuclear physicsNuclear and High Energy Physics010308 nuclear & particles physicsBranching fractionElectron–positron annihilation0103 physical sciencesPi010306 general physics01 natural sciencesStorage ringPhysical Review D
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Search for the rare decayB¯0→D*0γ

2005

SLAC for its support and the kind hospitality extended to them. This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), Institute of High Energy Physics (China), the Commissariat `a l’Energie Atomique and Institut National de Physique Nucl´eaire et de Physique des Particules (France), the Bundesministerium fu¨r Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Science and Technology of the Russian Federation, and …

PhysicsNuclear physicsNuclear and High Energy Physics010308 nuclear & particles physicsResearch council0103 physical sciencesLibrary scienceChristian ministryRussian federation010306 general physics01 natural sciences7. Clean energyBildungPhysical Review D
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Heavy quark parameters and |Vcb| from spectral moments in semileptonic B decays

2002

We extract the heavy quark masses and non-perturbative parameters from the Delphi preliminary measurements of the first three moments of the charged lepton energy and hadronic mass distributions in semileptonic B decays, using a multi-parameter fit. We adopt two formalisms, one of which does not rely on a 1/mc expansion and makes use of running quark masses. The data are consistent and the level of accuracy of the experimental inputs largely determines the present sensitivity. The results allow to improve on the uncertainty in the extraction of Vcb.

QuarkPhysicsParticle physicsSpectral momentsNuclear and High Energy Physics[PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex]010308 nuclear & particles physicsHadronHigh Energy Physics::PhenomenologyFOS: Physical sciences01 natural sciencesHigh Energy Physics - PhenomenologyHigh Energy Physics - Phenomenology (hep-ph)0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]High Energy Physics::ExperimentSensitivity (control systems)010306 general physicsParticle Physics - PhenomenologyLepton
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Observation ofηc(1S)andηc(2S)decays toK+K−π+π−π0in two-photon interactions

2011

We study the processes γγ→K_S^0K^±π^∓ and γγ→K^+K^-π^+π-π^0 using a data sample of 519.2fb^(-1) recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at center-of-mass energies near the Υ(nS) (n=2, 3, 4) resonances. We observe the η_c(1S), χ_(c0)(1P) and η_c(2S) resonances produced in two-photon interactions and decaying to K^+K^-π^+π^-π^0, with significances of 18.1, 5.4 and 5.3 standard deviations (including systematic errors), respectively, and report 4.0σ evidence of the χ_(c2)(1P) decay to this final state. We measure the η_c(2S) mass and width in K_S^0K^±π^∓ decays, and obtain the values m(η_c(2S))=3638.5±1.5±0.8  MeV/c^2 and Γ(η_c(2S))=13.4±4.6±3.2  MeV, wher…

Systematic errorPhysicsNuclear and High Energy Physics010308 nuclear & particles physicsBranching fractionResonanceState (functional analysis)01 natural sciencesMeasure (mathematics)law.inventionNuclear physicsParticle decaylaw0103 physical sciences010306 general physicsColliderPhysical Review D
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Search for $B^0_s-\overline{B^0_s}$ oscillations and a measurement of $B^0_d-\overline{B^0_d}$ oscillations using events with an inclusively reconstr…

2003

Neutral B meson oscillations in the B-s(0) - , and B-d(0) - systems were studied using a sample of about 4.0 million hadronic Z decays recorded by the DELPHI detector between 1992 and 2000. Events with a high transverse momentum lepton were removed and a sample of 770 k events with an inclusively reconstructed vertex was selected. The mass difference between the two physical states in the B-d(0) - system was measured to be: Deltam(d) = (0.531 +/- 0.025(stat.) +/- 0.007(syst.))ps(-1). The following limit on the width difference of these states was also obtained: DeltaGamma(Bd)/Gamma(Bd) oscillations was found, a limit on the mass difference of the two physical states was given:, Deltam(s) > …

PhysicsParticle physicsPhysics and Astronomy (miscellaneous)010308 nuclear & particles physicsPhysicsElectron–positron annihilationHadron01 natural sciencesVertex (geometry)Nuclear physics0103 physical sciencesTransverse momentumHigh Energy Physics::ExperimentB meson010306 general physicsEngineering (miscellaneous)LeptonThe European Physical Journal C
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Search for the decayB+→τ+ντ

2006

We search for the rare leptonic decay B^+ → τ^+ν_τ in a sample of 232 × 10^6 BB pairs collected with the BABAR detector at the SLAC PEP-II B-Factory. Signal events are selected by examining the properties of the B meson recoiling against the semileptonic decay B^- → D^9*0)l^-ν_ l. We find no evidence for a signal and set an upper limit on the branching fraction of B(B^+ → τ^+ν_τ)<2.8 × 10^9-4) at the 90% confidence level. We combine this result with a previous, statistically independent BABAR search for B+→τ+ντ to give an upper limit of B(B^+ → τ^+ν_τ)<2.6 × 10^(-4) at the 90% confidence level.

Semileptonic decayPhysicsNuclear physicsNuclear and High Energy PhysicsParticle physics010308 nuclear & particles physicsBranching fraction0103 physical sciencesCP violationB meson010306 general physics01 natural sciencesParticle identificationPhysical Review D
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MEASUREMENT OF THE FORWARD-BACKWARD ASYMMETRY OF CHARM AND BOTTOM QUARKS AT THE Z-POLE USING D-ASTERISK(+/-)-MESONS

1995

The forward-backward asymmetries for the processes $$e^ + e^ - \to c\bar c$$ and $$e^ + e^ - \to b\bar b$$ at theZ resonance are measured using identifiedD *± mesons. In 905,000 selected hadronic events, taken in 1991 and 1992 with the DEL-PHI detector at LEP, 4757D *+→D 0π+ decays are reconstructed. Thec andb quark forward-backward asymmetries are determined to be: $$\begin{gathered} A_{FB}^{c\bar c} = 0.077 \pm 0.029(stat) \pm 0.012(sys), \hfill \\ A_{FB}^{b\bar b} = 0.059 \pm 0.062(stat) \pm 0.024(sys). \hfill \\ \end{gathered} $$ Constraining theb asymmetry to the value measured by DELPHI using independent analyses, the charm asymmetry is determined to be: $$A_{FB}^{c,const} = 0.068 \pm…

QuarkParticle physicsPhysics and Astronomy (miscellaneous)MesonElectron–positron annihilationHadron01 natural sciencesDECAYSPartícules (Física nuclear)Charm quarkNuclear physicsDELPHI; forward-backward asymmetry; QCD0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]DECAYS; QCDCharm (quantum number)010306 general physicsEngineering (miscellaneous)DELPHIPhysics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyWeinberg angleQCDLARGE ELECTRON POSITRON COLLIDERPARTICLE PHYSICS; LARGE ELECTRON POSITRON COLLIDER; DELPHILarge Electron–Positron ColliderPARTICLE PHYSICSforward-backward asymmetryHigh Energy Physics::ExperimentCol·lisionadors d'hadronsParticle Physics - Experiment
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Search for scalar leptoquarks from Z$^0$ decays

1992

We have searched for pair produced scalar leptoquarks each decaying to a quark and a charged lepton in a sample of 116 000 hadronic Z0 events produced at LEP. No candidate was detected and cross section and branching ratio limits are set for the above process at 95% CL. Mass limits are found to be about 42 GeV/c2 depending only slightly on the models used and a coupling times branching ratio exclusion line is drawn for a scalar leptoquark with a free coupling. We have also probed the mass region above 45 GeV/c2 for a singly produced scalar leptoquark and set limits on the cross section and the coupling lambda(2)/4-pi up to 60 GeV.

QuarkLibraryNuclear and High Energy PhysicsParticle physicsLUND MONTE-CARLOElectron–positron annihilationHadronDigitisationArchive01 natural sciencesJET FRAGMENTATIONPHYSICSNuclear physicsLUND MONTE-CARLO; JET FRAGMENTATION; HADRONIC DECAYS; E+E; PHYSICS; BOSON0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]Leptoquark010306 general physicsPhysicsFoucault010308 nuclear & particles physicsBranching fractionHigh Energy Physics::PhenomenologyScalar (physics)BOSONE+EFísica nuclearHigh Energy Physics::ExperimentHADRONIC DECAYSParticle Physics - ExperimentLepton
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MEASUREMENT OF THE GAMMA(B-B-OVER-BAR)/GAMMA(HAD) BRANCHING RATIO OF THE Z BY DOUBLE HEMISPHERE TAGGING

1995

Two measurements of {Mathematical expression} are presented. Both measurements use 250000 Z decays taken with the DELPHI detector in 1991 and rely mainly on the precision of the microvertex detector. One tagging method is as simple as possible so that background rates can be reliably predicted by simulation. The other one uses a more involved tagging technique and reduces the dependence on simulation as much as possible. Combining both results, {Mathematical expression} is found to be 0.2209±0.0041(stat.)±0.0042(syst.)±0.0018 {Mathematical expression}. © 1995 Springer-Verlag.

Particle physicsPhysics and Astronomy (miscellaneous)LUND MONTE-CARLOB-HADRONSElectron–positron annihilationHadronElementary particle01 natural sciencesPartícules (Física nuclear)b taggingJET FRAGMENTATIONNuclear physics0103 physical sciences[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]010306 general physicsEngineering (miscellaneous)Detectors de radiacióDELPHIPhysicsE+E-PHYSICS010308 nuclear & particles physicsBranching fractionDetectormicrovertex detectorLUND MONTE-CARLO; JET FRAGMENTATION; HADRONIC DECAYS; E+E-PHYSICS; B-HADRONSb-taggingParticle accelerationDELPHI; microvertex detector; b taggingHADRONIC DECAYSParticle Physics - Experiment
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