0000000001107249

AUTHOR

Zhihao Xu

showing 14 related works from this author

Study ofJ/ψ→pp¯andJ/ψ→nn¯

2012

The decays J/psi -> p (p) over bar and J/psi -> n (n) over bar have been investigated with a sample of 225.2 x 10(6) J/psi events collected with the BESIII detector at the BEPCII e(+)e(-) collider. The branching fractions are determined to be B(J/psi -> p (p) over bar) = (2.112 +/- 0.004 +/- 0.031 x 10(-3) and B(J/psi -> n (n) over bar) =(2.07 +/- 0.01 +/- 0.17) x 10(-3). Distributions of the angle theta between the proton or antineutron and the beam direction are well described by the form 1 + alpha cos(2)theta, and we find alpha = 0.595 +/- 0.012 +/- 0.015 for J/psi -> p (p) over bar and alpha = 0.50 +/- 0.04 +/- 0.21 for J/psi -> n (n) over bar. Our branching- fraction results suggest a …

BaryonPhysicsNuclear and High Energy PhysicsQCD sum rulesProtonElectron–positron annihilationPhase angleAnalytical chemistryHigh Energy Physics::ExperimentAstrophysics::Earth and Planetary AstrophysicsNucleonAntineutronBar (unit)Physical Review D
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Search for high-mass dilepton resonances using 139 fb−1 of pp collision data collected at s=13 TeV with the ATLAS detector

2019

A search for high-mass dielectron and dimuon resonances in the mass range of 250 GeV to 6 TeV is presented. The data were recorded by the ATLAS experiment in proton–proton collisions at a centre-of-mass energy of s=13 TeV during Run 2 of the Large Hadron Collider and correspond to an integrated luminosity of 139 fb −1 . A functional form is fitted to the dilepton invariant-mass distribution to model the contribution from background processes, and a generic signal shape is used to determine the significance of observed deviations from this background estimate. No significant deviation is observed and upper limits are placed at the 95% confidence level on the fiducial cross-section times bran…

PhysicsNuclear and High Energy PhysicsParticle physicsLuminosity (scattering theory)Large Hadron Collider010308 nuclear & particles physicsBranching fractionMonte Carlo methodATLAS experimentResonance01 natural sciencesmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicineHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsBosonPhysics Letters B
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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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Electron and photon performance measurements with the ATLAS detector using the 2015-2017 LHC proton-proton collision data

2019

This paper describes the reconstruction of electrons and photons with the ATLAS detector, employed for measurements and searches exploiting the complete LHC Run 2 dataset. An improved energy clustering algorithm is introduced, and its implications for the measurement and identification of prompt electrons and photons are discussed in detail. Corrections and calibrations that affect performance, including energy calibration, identification and isolation efficiencies, and the measurement of the charge of reconstructed electron candidates are determined using up to 81 fb−1 of proton-proton collision data collected at √s=13 TeV between 2015 and 2017.

electronPhoton:Kjerne- og elementærpartikkelfysikk: 431 [VDP]Protonparticle identification: efficiency13000 GeV-cmsElectron01 natural sciences7. Clean energyParticle identificationphoton: particle identification030218 nuclear medicine & medical imagingParticle identification methods; Performance of high energy physics detectorsHigh Energy Physics - ExperimentSubatomär fysikHigh Energy Physics - Experiment (hep-ex)Particle identification methods0302 clinical medicineSubatomic Physics[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]scattering [p p]InstrumentationMathematical PhysicsPhysicsSettore FIS/01Performance of high energy physics detectorsLarge Hadron ColliderDetectorphotonATLAScalibration [energy]medicine.anatomical_structure:Nuclear and elementary particle physics: 431 [VDP]CERN LHC CollLHCParticle Physics - Experimentperformancep p: scatteringCiências Naturais::Ciências Físicas530 Physics:Ciências Físicas [Ciências Naturais]FOS: Physical sciencesNuclear physicsParticle identification method03 medical and health sciencesparticle identification: performanceAtlas (anatomy)0103 physical sciencesmedicineCalibrationddc:610High Energy PhysicsScience & Technologyelectron: particle identification010308 nuclear & particles physicshep-exenergy: calibrationefficiencyExperimental High Energy PhysicsPerformance of High Energy Physics Detectorsp p: colliding beamsexperimental results
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Studies of the resonance structure inD0→KS0K±π∓decays

2016

Amplitude models are constructed to describe the resonance structure of D0→ K-π+π+π- and D0→ K+π-π-π+ decays using pp collision data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb- 1. The largest contributions to both decay amplitudes are found to come from axial resonances, with decay modes D0→ a1(1260) +K- and D0→ K1(1270 / 1400) +π- being prominent in D0→ K-π+π+π- and D0→ K+π-π-π+, respectively. Precise measurements of the lineshape parameters and couplings of the a1(1260) +, K1(1270) - and K(1460) - resonances are made, and a quasi model-independent study of the K(1460) - resonance is performed. The coher…

PhysicsLarge Hadron Collider010308 nuclear & particles physicsResonance01 natural sciencesLuminosityNuclear physicsAmplitudePhase space0103 physical sciencesCoherence (signal processing)CP violationCharm (quantum number)Atomic physics010306 general physicsPhysical Review D
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Observation of Two NewN*Resonances in the Decayψ(3686)→pp¯π0

2013

Based on 106 x 10(6)psi(3686) events collected with the BESIII detector at the BEPCII facility, a partial wave analysis of psi(3686) -> p (p) over bar pi(0) is performed. The branching fraction of this channel has been determined to be B psi(3686) -> p (p) over bar pi(0) = (1.65 +/- 0.03 +/- 0.15) x 10(-4). In this decay, 7 N* intermediate resonances are observed. Among these, two new resonances, N(2300) and N(2570) are significant, one 1/2(+) resonance with a mass of 2300(-30-0)(+40+109) MeV/c(2) and width of 340(-30-58)(+30+110) MeV/c(2), and one 5/2(-) resonance with a mass of 2570(-10-10)(+19+34) MeV/c(2) and width of 250(-24-21)(+14+69) MeV/c(.)(2) For the remaining 5 N* intermediate r…

BaryonNuclear physicsPhysicsBranching fractionElectron–positron annihilationPartial wave analysisAnalytical chemistryGeneral Physics and AstronomyResonanceBar (unit)Physical 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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Search for weakly decaying b -flavored pentaquarks

2018

Investigations of the existence of pentaquark states containing a single $b$ (anti)quark decaying weakly into four specific final states J/$\psi K^+\pi^- p$, J/$\psi K^- \pi^- p$, J/$\psi K^- \pi^+ p$, and $J/\psi \phi (1020) p$ are reported. The data sample corresponds to an integrated luminosity of 3.0/fb in 7 and 8 TeV pp collisions acquired with the LHCb detector. Signals are not observed and upper limits are set on the product of the production cross section times branching fraction with respect to that of the $\Lambda_b$.

baryon: exoticPhysics and Astronomy (miscellaneous)7000 GeV-cms8000 GeV-cms01 natural sciencesPhysics Particles & FieldsSettore FIS/04 - Fisica Nucleare e SubnucleareHigh Energy Physics - ExperimentLuminosityHigh Energy Physics - Experiment (hep-ex)Hadron-Hadron scattering (experiments)scattering [p p][PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]exotic [baryon]LHCb - Abteilung HintonpentaquarkPhysics8000 GeV-cmsPhysicsParticle physicsPentaquark3. Good healthchannel cross section: branching ratio: upper limitExotic baryonpentaquark --> J/psi(3100) K- pi+ pBranching fraction Hadron-Hadron scattering (experiments) QCDpentaquark --> J/psi(3100) K- pi- pCERN LHC Coll7000 GeV-cmsPhysical Sciencespentaquark --> J/psi(3100) Phi(1020) pBranching fractionLHCcolliding beams [p p]Particle Physics - ExperimentQuarkParticle physicsp p: scatteringFOS: Physical sciencesAstronomy & AstrophysicsHadronsNOmultiquark[ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex]0103 physical sciencesddc:530010306 general physicsLarge Hadron Collider (France and Switzerland)Science & Technologybranching ratio: upper limit [channel cross section]hep-ex010308 nuclear & particles physicsBranching fractionpentaquark --> J/psi(3100) K+ pi- pParticles and FieldGran Col·lisionador d'HadronsBottom quarkQCDLHC-BHEPLHCbHigh Energy Physics::ExperimentFísica de partículesExperimentsp p: colliding beamsexperimental resultsPhysical Review D
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Partial wave analysis ofJ/ψ→γηη

2013

Based on a sample of 2.25 x 10(8) J/psi events collected with the BESIII detector at BEPCII, a full partial wave analysis on J/psi -> gamma eta eta was performed using the relativistic covariant tensor amplitude method. The results show that the dominant 0(++) and 2(++) components are from the f(0)(1710), f(0)(2100), f(0)(1500), f(2)'(1525), f(2)(1810) and f(2)(2340). The resonance parameters and branching fractions are also presented.

PhysicsNuclear and High Energy PhysicsAmplitudeClassical mechanicsMesonBranching fractionElectron–positron annihilationPartial wave analysisAnalytical chemistryddc:530High Energy Physics::ExperimentPhysical Review D
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Measurement of the branching fraction of the decay Bs0→KS0KS0

2020

A measurement of the branching fraction of the decay Bs0→KS0KS0 is performed using proton-proton collision data corresponding to an integrated luminosity of 5 fb-1 collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(Bs0→KS0KS0)=[8.3±1.6(stat)±0.9(syst)±0.8(norm)±0.3(fs/fd)]×10-6, where the first uncertainty is statistical, the second is systematic, and the third and fourth are due to uncertainties on the branching fraction of the normalization mode B0→φKS0 and the ratio of hadronization fractions fs/fd. This is the most precise measurement of this branching fraction to date. Furthermore, a measurement of the branching fraction of the decay B0…

PhysicsNuclear physicsNormalization (statistics)010308 nuclear & particles physicsBranching fraction0103 physical sciences010306 general physics01 natural sciencesHadronizationPhysical Review D
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First Observation of theM1Transitionψ(3686)→γηc(2S)

2012

Using a sample of 106×10(6) ψ(3686) events collected with the BESIII detector at the BEPCII storage ring, we have made the first measurement of the M1 transition between the radially excited charmonium S-wave spin-triplet and the radially excited S-wave spin-singlet states: ψ(3686)→γη(c)(2S). Analyses of the processes ψ(3686)→γη(c)(2S) with η(c)(2S)→K(S)(0)K(±)π(∓) and K(+)K(-)π(0) give an η(c)(2S) signal with a statistical significance of greater than 10 standard deviations under a wide range of assumptions about the signal and background properties. The data are used to obtain measurements of the η(c)(2S) mass (M(η(c)(2S))=3637.6±2.9(stat)±1.6(syst) MeV/c(2)), width (Γ(η(c)(2S))=16.9±6.4(…

PhysicsBranching fractionElectron–positron annihilationExcited stateAnalytical chemistryGeneral Physics and AstronomyPhysical Review Letters
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Search for a light exotic particle inJ/ψradiative decays

2012

Using a data sample containing 1.06x10^8 psi' events collected with the BESIII detector at the BEPCII electron-positron collider, we search for a light exotic particle X in the process psi' -> pi^+ pi^- J/psi, J/psi -> gamma X, X -> mu^+ mu^-. This light particle X could be a Higgs-like boson A^0, a spin-1 U boson, or a pseudoscalar sgoldstino particle. In this analysis, we find no evidence for any mu^+mu^- mass peak between the mass threshold and 3.0 GeV/c^2. We set 90%-confidence-level upper limits on the product-branching fractions for J/psi -> gamma A^0, A^0 -> mu^+ mu^- which range from 4x10^{-7} to 2.1x10^{-5}, depending on the mass of A^0, for M(A^0)<3.0 GeV/c^2. On…

BOSONSPhysicsNuclear and High Energy PhysicsParticle physicsRange (particle radiation)ENERGIESElectron–positron annihilationGRAVITINOFOS: Physical sciencesSupersymmetryHigh Energy Physics - Experimentlaw.inventionNuclear physicsPseudoscalarHigh Energy Physics - Experiment (hep-ex)lawSgoldstinoRadiative transferHigh Energy Physics::ExperimentColliderBosonPhysical Review D
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Observation of a Charged Charmoniumlike Structure ine+e−→(D*D¯*)±π∓ats=4.26  GeV

2014

We study the process e(+)e(-) -> (D* (D) over bar*)(+/-)pi(-/+) at a center-of-mass energy of 4.26 GeV using a 827 pb(-1) data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be (137 +/- 9 +/- 15) pb. We observe a structure near the (D* (D) over bar*)(+/-) threshold in the pi(-/+) recoil mass spectrum, which we denote as the Z(c)(+/-) (4025). The measured mass and width of the structure are (4026.3 +/- 2.6 +/- 3.7) MeV/c(2) and (24.8 +/- 5.6 +/- 7.7) MeV, respectively. Its production ratio sigma(e(+)e(-) -> Z(c)(+/-)(4025)pi(-/+)-> (D* (D) over bar*)(+/-)pi(-/+)/sigma(e(+)e…

PhysicsHigh energyPositronRecoilElectron–positron annihilationMass spectrumAnalytical chemistryPiGeneral Physics and AstronomyHigh Energy Physics::ExperimentBar (unit)Physical Review Letters
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Measurement of the W boson mass

1996

The W boson mass is measured using proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 1.7fb(-1) recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q/p(T) distribution of a sample of W ->mu y decays and the phi* distribution of a sample of Z -> mu mu decays the W boson mass is determined to be

13000 GeV-cmsTevatronparton: distribution functionQC770-798W: leptonic decay7. Clean energy01 natural sciencesLuminosityPhysics Particles & FieldsSubatomär fysikHadron-Hadron scattering (experiments)scattering [p p]Electroweak interactionNuclear Experimentparticle identification [muon]Settore FIS/01PhilosophyPhysicsCoupling (probability)CERN LHC CollHadron colliderPhysical SciencesTransverse masscolliding beams [p p]distribution function [parton]Collider Detector at FermilabParticles and fieldCOLLISIONSp p: scatteringCERN PBARP COLLIDERAstrophysics::High Energy Astrophysical PhenomenaW: mass: measuredStandard ModelNuclear physicsddc:530010306 general physics0206 Quantum PhysicsMuonScience & Technology010308 nuclear & particles physicsWeinberg angleHEPFERMILAB TEVATRONElectroweak interaction Hadron-Hadron scattering (experiments) QCD For- ward physicsCDFp p: colliding beamsPhysics::Instrumentation and DetectorsElectron–positron annihilation= 1.8 TEVGeneral Physics and Astronomy= 1.8 TEV; PBARP COLLISIONS; DECAYVector bosonHigh Energy Physics - ExperimentHigh Energy Physics - Experiment (hep-ex)Computer Science::Systems and ControlSubatomic Physics[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]PhysicFermilabBosonPhysics0105 Mathematical PhysicsStatistics::ApplicationsSettore FIS/01 - Fisica Sperimentalestatistical [error]Nuclear & Particles PhysicsCENTRAL TRACKING CHAMBERerror: statisticalCENTRAL ELECTROMAGNETIC CALORIMETERTransverse momentum0202 Atomic Molecular Nuclear Particle and Plasma PhysicsLHCmass: measured [W]Particle Physics - ExperimentStatistics::TheoryParticle physicsNuclear and High Energy Physicselectroweak interaction: precision measurementRegular Article - Experimental PhysicsTRANSVERSE ENERGYFOS: Physical sciencesmuon: particle identification530Particle decayPBARP COLLISIONSNuclear and particle physics. Atomic energy. Radioactivityprecision measurement [electroweak interaction]0103 physical sciencesForward physicVECTOR BOSONElectroweak interaction Hadron-Hadron scattering (experiments) QCD Forward physicsCERN PBARP COLLIDER; CENTRAL ELECTROMAGNETIC CALORIMETER; CENTRAL TRACKING CHAMBER; = 1.8 TEV; PARTON DISTRIBUTIONS; FERMILAB TEVATRON; VECTOR BOSON; TRANSVERSE ENERGY; CDF; COLLISIONShep-exHigh Energy Physics::PhenomenologyLHC-BQCDleptonic decay [W]LHCbPARTON DISTRIBUTIONSMass spectrumForward physicsPhysics::Accelerator PhysicsHigh Energy Physics::ExperimentDECAYHumanitiesexperimental results
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