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Mini-review of rare charmonium decays at BESⅢ

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Chinese Physics C 2012年第10期36卷 932-940页

作者：李海波朱世海 Institute of High Energy Physics Chinese Academy of Sciences

Recently, the LHCb experiment announced 3.5σ evidence for direct CP violation in D0 decay by looking at the difference between A CP （D0 → K＋ K- ） and A CP （D0 →π＋ π- ）. This is the first evidence of CP violation in a charm system, which may indicate new physics beyond the Standard Model. Motivated by this measurement, we review rare processes in charmonium decay, especially, the weak decay, C or P violated decay, and lepton flavor violated decays. In case the new physics appears in charm sector, these rare decays of charmonium states will provide an opportunity to search for significant contributions from physics beyond the Standard Model. With huge J/ψ and ψ（2S） samples in BES experiment, the rare decays may be feasible.

关键词： BESⅢ charmonium weak decay new physics lepton flavor violation

Properties of charmonium States in a Phenomenological Approach

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Communications in Theoretical Physics 2019年第2期71卷 192-202页

作者： Praveen P D’Souza Antony Prakash Monteiro K.B.Vijaya Kumar Department of Physics St Philomena College Department of Physics Mangalore University

We investigate the spectrum and decay rates of charmonium states within the framework of the non relativistic quark model by employing a Coulomb like potential from the perturbative one gluon exchange and the linear confining potential along with the potential derived from instanton vacuum to account for the hyperfine mass splitting of charmonium states in variational approach. We predict radiative E1, M1, two-photon, lepton and two-gluon decay rates of low lying charmonium states. An overall agreement is obtained with the experimental masses and decay widths.We have estimated the branching ratio of two gluons decaying into light hadrons.

关键词： non-relativistic quark model instantons charmonium radiative decay two gluon decay two photon decay leptonic decay branching ratio

Lattice study of two-photon decay widths for scalar and pseudo-scalar charmonium

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Chinese Physics C 2020年第8期44卷 88-97页

作者：陈莹宫明荔宁刘川刘玉斌刘朝峰马建平孟雨熊超张克龙无 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China School of Physics University of Chinese Academy of SciencesBeijing 100049China School of Science Xi’an Technological UniversityXi’an 710032China School of Physics and Center for High Energy Physics Peking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China School of Physics Nankai UniversityTianjin 300071China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China School of Physics Peking UniversityBeijing 100871China CLQCD Collaboration

This exploratory study computes two-photon decay widths of pseudo-scalar(ηc)and scalar(χc0)charmonium using two ensembles of Nf=2 twisted mass lattice QCD gauge configurations.The simulation is performed using two lattice ensembles with lattice spacings a=0.067 fm with size 323×64 and a=0.085 fm with size 243×48.The decay widths for the two charmonia are obtained within the expected ballpark,but are however smaller than the experimental ones.Possible reasons for these discrepancies are discussed.

关键词： charmonium decay width lattice QCD

Production of charmonium(like) states in e^+ e^- interactions

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Chinese Physics C 2008年第6期32卷 488-491页

作者： P.Pakhlov Institute for Theoretical and Experimental Physics B.Cheremushkinskaya25117218MoscowRussia

We present a search for new charmonium like states in e^＋e^- annihilation using the initial-state radiation and the process e^＋e^- →J/ψ D（^＊）D（^＊）. The analyses are based on a huge data sample recorded near ... 详细信息

关键词： charmonium new states e^＋e^- annihilation initial state radiation

Study of charmonium(-like) states via ISR at Belle

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Chinese Physics C 2008年第6期32卷 452-454页

作者：苑长征 Institute of High Energy Physics CAS

The cross sections for e^＋e^- →π^＋ π^-J/ψ, π^＋π^-ψ（2S）, K^＋K^-J/ψ, DD1D^0D1-π^＋＋c.c., D^＊D＋c.c., and D^＊D^＊ are measured using data sample collected on or near the T（4S） resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c^2, corresponding to the so called Y（4260）, is observed in π^＋π^-J/ψ final state. In addition, there is another cluster of events at around 4.05 GeV/c^2. Two resonant structures are observed in the π^＋π^-ψ（2S） invariant mass distribution, one at 4361±9±9 MeV/c^2 with a width of 74±15±10 MeV/c2, and another at 4664 ±11±5 MeV/c2 with a width of 48±15±3 MeV/c^2. The rich structures observed in all these final states indicate that our understanding of the vector charmonium states above the open charm threshold is still poor, let alone the other possible dynamics such as charmonium hybrids or final state re-scattering and so on.

关键词： initial state radiation cross section charmonium charmed mesons

1-18 Fano Scheme of charmonium States with Asymmetric Line Shape

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IMP & HIRFL Annual Report 2015年第1期 29-30页

作者： Cao Xu 不详

Asymmetric line shape of states is a distinguished characteristic which is often encountered when thresholds and states interacts. Fifty years ago, Fano[1] that the interaction of bare states with one or several thresholds of continua would give rise to special asymmetric peaks of the corresponding resonances, which is a common interference phenomenon in quantum physics. It is more obvious for sharp resonances, e:g:, heavy quarkonium states, because their widths are smaller by orders of magnitudes than their masses. The (3770) state is narrow with a width of around 30 MeV and locates about 35 MeV above the D￣D threshold. It is ideal to investigate how this threshold effect influences the properties of states.

关键词： Fano Scheme charmonium

Lattice calculation ofχ_(c0)→2γdecay width

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Chinese Physics C 2022年第5期46卷 20-28页

作者：邹作恒孟雨刘川 School of Physics Peking UniversityBeijing 100871China Center for High Energy Physics Peking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China

We perform a lattice QCD calculation of theχ_(c0)→2γdecay width using a model-independent method that does not require the momentum extrapolation of corresponding off-shell form factors.The simulation is performed on ensembles of N_(f)=2 twisted mass lattice QCD gauge configurations with three different lattice spacings.After the continuum extrapolation,the decay width is obtained to beΓ_(γγ)(χ_(c0))=3.65(83)_(stat)(21)_(lat.syst)(66)_(syst)keV.Regardless of this large statistical error,our result is compatible with the experimental results within 1.3σ.Potential improvements of the lattice calculation in the future are also discussed.

关键词： charmonium decay width lattice QCD

Using X（3823）→J/ψπ＋π- to identify coupled-channel effects

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Frontiers of physics 2016年第3期11卷 151-159页

作者： Bo Wang Hao Xu Xiartg Liu Dian-Yong Chen Susana Coito Estia Eichten Research Center for Hadron and CSR Phys~ics Lanzhou University and Institute of Modern Physics of CAS Lanzhou 730000 China School of Physical Science and Technology Lanzhou University Lanzhou 730000 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Theoretical Physics Department Fermilab IL 60510 USA

Very recently, the Belle and BESIII experiments observed a new charmonium-like state X（3823）, which is a good candidate for tile D-wave charmonium （13D2）. Because the X（3823） is just near the DD＊ threshold, the decay X（3823）→J/ψπ＋π- can be a golden channel to test the significance of coupled-channel effects. In this work, this decay is considered including both the hidden-charm dipion and the usual quantum chromodynamics multipole expansion （QCDME） contributions. The partial decay width, the dipion invari^nt mass spectrum distribution dF[X（3823） →J/ψπ＋π- /dmπ＋π-, and the corresponding dF[X（3823） →J/ψπ＋π-/d cosθ distribution are computed. Many param- eters are determined from exi：sting experimental data, so the results depend mainly only on one unknown phase between the QCDME and hidden-charm dipion amplitudes.

关键词： charmonium Hidden-charm dipion decay

An exclusive event generator for e^+ e^- scan experiments

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Chinese Physics C 2014年第8期38卷 1-6页

作者：平荣刚 Institute of High Energy Physics Chinese Academy of Sciences

An exclusive event generator is designed for e＋e- scan experiments, including initial state radiation effects up to the second order correction. The generator is coded within the framework of BesEvtGen. There are seventy hadronic decay modes available, with effective center-of-mass energy coverage from the two pion mass threshold up to about 6 GeV. The accuracy achieved for the initial state radiation correction reaches the level achieved by the KKMC generator. The uncertainty associated with the calculation of the correction factor to the initial state radiation is dominated by the measurements of the energy-dependent Born cross section.

关键词： event generator charmonium exclusive decays