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Angular Distribution of Production Planes in j/ψ→■ Decay

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Chinese Physics Letters 2019年第6期36卷 21-23页

作者： Qiaorong Shen Xinyan Tong Yunfei Long Yajun Mao School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University

A new observable, the angle between ■ decay planes, is proposed to test the theoretical predictions on the spin correlation. With 10 billion j/ψ events collected with the BES Ⅲ detector at the BEPCⅡ e^+e^- collide... 详细信息

关键词： j/ψ BEPCⅡ spin BES

j/ψ→μ～+μ～- reconstruction in the CMS experiment

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Chinese Physics C 2009年第3期33卷 161-169页

作者：杨宗长钱思进 State Key Laboratory of Nuclear Science and Technology Peking University

In this paper the j/ψ→μ^＋μ^- reconstruction performance in the CMS experiment at the LHC is studied in detail by using B8→j/ψφ→μμKK events. The reconstruction efficiencies of j/ψ mesons and their decay muons are obtained as a function of the transverse momentum PT and the pseudo-rapidity η. We also study the muon trigger efficiency for this channel with the planned Level-1 trigger and High Level Trigger selection criteria. It was observed that the muon reconstruction efficiency decreases when the two decay muons have a small or large 3D angular separation, which further affects the overall j/ψ reconstruction efficiency.

关键词： CMS j/ψ reconstruction efficiency Level-1 trigger HLT (High Level Trigger)

Feasibility study of a j/ψ cross section measurement with early CMS data

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Chinese Physics C 2009年第8期33卷 609-616页

作者：杨宗长钱思进 State Key Laboratory of Nuclear Science and Technology Peking University

We report the methods and plans for measuring the differential cross section of j/ψ→μ^＋μ^- production, using data to be collected in the first LHC run by the CMS detector. Making use of the large B-hadron lifetime, we show how to separate the promptly produced j/ψ’s from those coming from B-hadron decays. Since the j/ψ production cross section is expected to be large, the analysis should be viable with relatively small data sets, that will become available early in the startup of the LHC. We also address effects of a non-perfect detector alignment, as well as systematic uncertainties. About 70 thousand j/ψ decays are reconstructed from Monte Carlo data, which corresponds to an integrated luminosity of 3 pb^-1 in 14 TeV collisions, in the range of pT^j/ ψbetween 5 and 40 GeV/c. The precision of the result is limited by systematic uncertainties, and is at the 15% level.

关键词： j/ψ CMS B-hadron QCD

Ansatzs, Assumptions and Production of j/ψ-Particles: A Non-charmed Approach versus Charmed Ones

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Chinese Physics Letters 2012年第2期29卷 67-70页

作者： P.Guptaroy Goutam Sau S.Bhattacharyya Department of Physics Raghunathpur CollegeRaghunathpur 723133Purulia(WB)India Beramara Ram Chandrapur High School South 24-Parganas743609(WB)India Physics and Applied Mathematics Unit(PAMU) Indian Statistical Institute203 B.T.RoadKolkata-700108India

We look at some crucial aspects of j/ψ-production in a few high energy nuclear collisions in the light of a nonstandard model which is outlined in the *** underlying physical ideas,assumptions and ansatzs are also enunciated in some *** results are in fairly in good agreement with both measured data and the results obtained on the basis of other models of the standard *** impact and implications of this comparative study are also discussed.

关键词： j/ψ One fairly

Study of the rare decay j/ψ→e^+e^-φ

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Chinese Physics C 2016年第7期40卷 28-31页

作者：郭星导薛思润柯红卫李学潜赵强 School of Physics Nankai University Institute of High Energy Physics and Theoretical Physics Center for Science Facilities Chinese Academy of Sciences Department of Physics Tianjin University

We study the decay process of j/ψ→ e＋e-φ where the relatively clean electromagnetic （EM） transitions appear at leading order at tree level while the hadronic contributions only emerge via hadronic loop transitions. We include the low-lying scalar f0（980） and pseudoscalar η/η′ as the dominant contributions in the evaluation of the hadronic loop contributions. It is found that the hadronic effects are negligible compared with the EM contributions. The decay width of j/ψ→ e＋e-φis determined to be about 2.12 × 10^-6 keV if there is no other leading mechanism contributing. This result will be tested by the BESIII experiment with a large j/ψ data sample.

关键词： rare decay j/ψ looptools

New signature of low mass Z'in j/ψdecays

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Chinese Physics C 2024年第8期48卷 1-5页

作者： Chao-Qiang Geng Chia-Wei Liu jiabao Zhang School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China Tsung-Dao Lee Institute&School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Institute of Theoretical Physics University of Chinese Academy of SciencesBeijing 100190China

We explored a new approach to search for a low-mass Z′particle through j/ψdecays by identifying its existence through parity-violating phenomena in the isospin-violating final states ofΛΣ¯^(0)and the corresponding charge conjugated states ofΛΣ¯^(0).Our investigation centered on a generation-independent and leptophobic Z′with mass below 10 *** the present experimental conditions at Beijing Spectrometer III(BESIII)and the anticipated opportunities at the Super Tau Charm Factory(STCF),we conducted Monte-Carlo simulations to predict possible events at both ***,we foresee a substantial enhancement in the precision of the lower limit estimation ofαNP as well as a reduction in statistical uncertainty with upcoming STCF ***,it is essential to highlight that a null result in the measurement ofαNP would impose stringent constraints,requiring the Z′−q−q couplings to be in the order of 10^(−2).

关键词： Z′ parity violation j/ψ

Calculations of differential momentum transfer spectra for j/ψphotoproduction in heavy-ion collisions

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Chinese Physics C 2022年第7期46卷 112-117页

作者： Pengfei Wang Xin Wu Wangmei Zha Zebo Tang State Key Laboratory of Partiele Deleetion and Eleetronics University of Seienee and Technology of China Hefei 230026 China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

Understanding the gluonic structure in nuclei is one of the most important goals in modern nuclear physics,for which j/ψphotoproduction is suggested as a powerful tool to probe the gluon density *** experimental investigation of the photoproduction process is conventionally studied in ultra-peripheral heavy-ion collisions,and has recently been extended to hadronic ***,theoretical efforts in hadronic heavy-ion collisions are still lacking in the *** this paper,we build up a phenomenological framework to calculate the differential momentum transfer spectra for j/ψphotoproduction in hadronic heavy-ion collisions based on a vector meson dominance *** the first time,we include the effect of internal photon radiation in the calculations,and we find that the results with internal photon radiation could describe the experimental measurements from STAR very well.

关键词： photoproduction j/ψ heavy-ion collision internal photon radiation

Molecular components in j/ψandρ-πpuzzle

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Chinese Physics C 2024年第5期48卷 141-150页

作者：郭星导陈殿勇李学潜苑仲元桑士晶 College of Physics and New Energy Xuzhou University of TechnologyXuzhou 221111China School of Physics Southeast UniversityNanjing 211189China Department of Physics Nankai UniversityTianjin 300071China Lanzhou Center for Theoretical Physics Lanzhou UniversityLanzhou 730000China

Motivated by the large branching fractions of j/ψ→f0(1710)ω/f0(1710)ϕand the light exotic candidates,we found that there may exist molecular states composed of f0(1710)ωand f0(1710)ϕ,which correspond to X(2440)and X(2680)observed a few decades *** branching fractions of X(2440)and X(2680)to various PV and KKω(ϕ)channels were estimated in the molecular *** addition,the large branching fractions of j/ψ→f0(1710)ω/f0(1710)ϕindicate sizable molecular components in the j/ψ***,we consider j/ψas the superposition of thecc¯(1S),f0(1710)ω,and f0(1710)ϕmolecular *** molecular components have a significant impact on the light hadron decays of j/ψ,which may elucidate the long standingρ−πpuzzle.

关键词： ρ-πpuzzle j/ψ molecular state

Study of C parity violating and strangeness changing j/ψ→ PP weak decays

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Chinese Physics C 2021年第8期45卷 45-53页

作者： Yueling Yang junliang Lu Mingfei Duan jinshu Huang junfeng Sun Institute of Particle and Nuclear Physics Henan Normal UniversityXinxiang 453007China School of Physics and Electronic Engineering Nanyang Normal UniversityNanyang 473061China

Although j/ψ weak decays are rare,they are possible within the standard model of elementary *** by the potential prospects of the future intensity frontier,the C parity violating j/ψ→πη^(′),ηη′decays and the strangeness changing j/ψ→πK,Kη^(′)decays are studied via the perturbative QCD *** is determined that the j/ψ→ηη^(′) decays have relatively large branching ratios,approximately on the order of 10^(11),which might be within the measurement capability and sensitivity of the future STCF experiment.

关键词： j/ψ weak decay perturbative QCD factorization