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Chang-Zheng Yuan

Publications and source records attributed to Chang-Zheng Yuan.

36 records · Page 2Linked to original sources
arXiv2019

Determination of the absolute branching fractions of X(3872) decays

We report the first determination of the absolute branching fractions of the X(3872) decays by globally analyzing the measurements provided by the Belle, BaBar, BESIII, and LHCb experiments. The branching fractions of X(3872) to pi^+pi^- J/psi and D*0D0bar+c.c. are found to be (4.1^{+1.9}_{-1.1})% and (52.4^{+25.3}_{-14.3})%, respectively. The branching fractions of the decays X(3872) to gamma J/psi, gamma psi', omega J/psi, and pi^0 chi_{c1} are also determined. The global fit implies that the fraction of X(3872) decays which are not observed in experiments is (31.9_{-31.5}^{+18.1})%, which indicates that there is still a lot of room for searching for new decay modes of the X(3872). With the branching fraction, we determine the production cross section of e+e- to gamma X(3872) at center-of-mass energy 4.226 GeV.

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arXiv2019

The XYZ states revisited

The BESIII and the LHCb became the leading experiments in the study of the exotic states after the Belle and BaBar experiments finished their data taking in the first decade of this century. We review the progress in the study of the XYZ states at BESIII and LHCb experiments with their unique data samples in $e^+e^-$ annihilation at center-of-mass energies of 3.8--4.6~GeV and in pp collision at center-of-mass energies 7, 8, and 13~TeV, respectively. With these data samples, we have deepened our understanding of the most famous charmonium-like states X(3872), Y(4260), Z_c(3900), and Z_c(4430), as well as other similar states like the Y(4140) and X(3823). We review the progress in the study of these states, and also discuss perspectives at future experiments.

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arXiv2018

A novel method of reconstructing semileptonic $B$ decays

Semileptonic decays of charged and neutral $B$ mesons play a critical role in the determination of the magnitudes of the CKM-matrix elements $V_{cb}$ and $V_{ub}$, and in the test of the lepton universality which is a basic assumption of the Standard Model. Due to the missing neutrino in the semileptonic decays, the measurements depend strongly on the tag efficiency of the $B$ meson in the recoil side which is at a few per mille to a few per cent level, and this values a limiting factor for high precision measurement and high sensitivity test mentioned above. We develop a novel method of reconstructing semileptonic decays of the $B$ mesons by introducing the $B$ momentum information calculated from the $B$ decay vertex and the interaction point, as well as the kinematic information of $e^{+}e^{-}\to B\overline{B}$ at the $B$-factories such as BaBar, Belle, and Belle II. As this method does not depend on the reconstruction of the $B$ meson in the recoil side, the gain in the efficiency could be as large as two orders of magnitudes. This makes high precision measurement of CKM-matrix elements $|V_{cb}|$ and $|V_{ub}|$ and high precision test of lepton universality at $B$-factories more promising. We present the algorithms for the semileptonic decays of neutral and charged $B$ mesons separately, as they are affected by the magnetic field in the detector differently.

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arXiv2018

Derived Born cross sections of $e^+e^-$ annihilation into open charm mesons from CLEO-c measurements

The exclusive Born cross sections of the production of $D^0$, $D^+$ and $D_s^+$ mesons in $e^+e^-$ annihilation at 13 energy points between 3.970 and 4.260 GeV are obtained by applying corrections for initial state radiation and vacuum polarization to the observed cross sections measured by CLEO-c experiment. Both the statistical and the systematic uncertainties for the obtained Born cross sections are properly estimated.

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arXiv2016

Sensitivity Study of Searching for $τ^- \to γμ^-$ at HIEPA

The charged lepton flavor violation process is a clean and sensitive probe of new physics beyond the Standard Model. A sensitivity study is performed to the process $τ^- \to γμ^-$ based on a 3~fb$^{-1}$ inclusive Monte Carlo sample of $e^+e^-$ collisions at a center-of-mass energy of 4.26 or 4.6~GeV, in the framework of the BESIII software system. The 90\% confidence level upper limits on $\BR(τ^- \to γμ^-)$ are estimated assuming no signal is produced. We also obtain the sensitivity on $\BR(τ^- \to γμ^-)$ as a function of the integrated luminosity, to serve as a reference for the HIEPA being proposed in China. It is found that 6.34~ab$^{-1}$ are needed to reach the current best upper limit of $4.4\times 10^{-8}$ and about 2510~ab$^{-1}$ are needed to reach a sensitivity of $10^{-9}$ if the detector design is similar to that of BESIII.

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arXiv2015

New results on the XYZ states from Belle experiment

We review the results on the XYZ states from the Belle experiment, including the measurement of inclusive hadronic cross sections and exclusive cross sections in e+e- annihilation and the Z_b states in the bottomonium energy region; and the study of the Y states and the Z_c states in charmonium energy region.

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arXiv2015

Study of the XYZ states at the BESIII

With its unique data samples at energies of 3.8--4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charmonium-like states, i.e., the XYZ states. We review the results for observations of the Zc(3900) and Zc(4020) states, the X(3872) in e+e- annihilation, and charmonium psi(1^3D_2) state, as well as measurements of the cross-sections of omega chi_cJ and eta J/psi, and the search for e+e- to gamma chi_cJ and gamma Y(4140). We also present data from BESIII that may further strengthen the study of the XYZ and conventional charmonium states, and discuss perspectives on future experiments.

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arXiv2014

Evidence for resonant structures in e+e- to pi+pi-h_c

The cross sections of e+e- to pi+pi-h_c at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BESIII and the CLEO-c experiments. Resonant structures are evident in the e+e- to pi+pi-h_c line shape, the fit to the line shape results in a narrow structure at a mass of (4216\pm 18) MeV/c^2 and a width of (39\pm 32) MeV, and a possible wide structure of mass (4293\pm 9) MeV/c^2 and width (222\pm 67) MeV. Here the errors are combined statistical and systematic errors. This may indicate that the Y(4260) state observed in e+e- to pi+pi-J/psi has fine structure in it.

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arXiv2014

Recent progress on the study of the charmoniumlike states

In this article, we review the recent experimental studies on the charmoniumlike states, mainly from the e+e- annihilation experiments BESIII, Belle, BaBar, and CLEO-c, and the hadron collider experiment LHCb. We discuss the results on the X(3872), the vector Y states [Y(4008), Y(4660), and those in e+e- to pi+pi-h_c], and the charged charmoniumlike Z_c^- states.

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arXiv2013

New results on XYZ states from e+e- experiments

In this talk, we present the recent study on the charmoniumlike states from the e^+e^- colliders, including BESIII, Belle, BaBar, and CLEOc. The talk covers the X(3872) from the Y(4260) radiative transition, the Y states from the initial-state-radiation processes and from e+e- to pi+pi-h_c, and the charged Z_c states.

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arXiv2010

Review on low and high mass spectroscopy

We review the most recent experimental progress in the hadron spectroscopy, up to bottomonium mass. This covers the search for the J^PC=1^-+ exotic state, the states in J/psi decays, the spin-singlets of heavy quarkonium, and the charmoniumlike XYZ states.

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arXiv2009

Exotic Hadrons

In this talk, we review the most recent progress in the searching for the exotic hadrons, including hybrids, multi-quark states, molecules and so on. We only focus on the studies with a charmonium and one or more light mesons in the final states. This covers the X(3872), the $XYZ$ states at around 3.940 GeV, the Y(4140) and X(4350) in two-photon collisions, the $Y$ states from $ISR$ processes, and the charged $Z$ states.

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arXiv2008

Recent BES Results on Hadron Spectroscopy

We present recent results from the BES experiment on the observation of the Y(2175) in J/ψ\to ϕf_0(980) η, study of η(2225) in J/ψ\to γϕϕ, and the production of X(1440) recoiling against an ωor a ϕin J/ψhadronic decays. The observation of ψ(2S) radiative decays is also presented.

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arXiv2007

Recent BES results on charmonium decays

In this talk, we present the recent results on charmonium decays from the BES experiment at the BEPC collider. The analyses are based on a 14 million psi(2S) events data sample. We report results on leptonic decays, hadronic decays, and radiative decays of psi(2S), as well as hadronic decays of chi_cJ states and rare or forbidden decays of J/psi.

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arXiv2006

Results from Charmonium Decays

Recent results from BES and CLEOc experiments on charmonium decays using J/psi, psi' and psi'' data samples collected in e+e- annihilation are reviewed, including the measurement of the relative phase between strong and electromagnetic decays of psi', the study of the ``rho pi puzzle'' in J/psi and psi' decays, and the search for the non-DDbar decays of psi''. The decays of chi_cJ produced in psi' radiative transition are also reviewed. These new results shed light on the understanding of QCD.

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arXiv2005

Hadron Spectroscopy from BES and CLEOc

Recent results from BES and CLEOc experiments on hadron spectroscopy and charmonium decays using J/psi, psi' and psi'' data samples collected in e+e- annihilation are reviewed, including the observation of X(1835) in J/psi --> gamma pi+ pi- eta', study of the scalar particles in J/psi radiative and hadronic decays, as well as in chi_c0 hadronic decays, and the study of the ``ρπpuzzle'' in J/psi, psi', and psi'' decays. We also make a few comments on partial wave analysis, and the study of the ρπpuzzle.

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arXiv2004

Hadronic decays of charmonia from BESII

Recent results on charmonia decays at BESII/BEPC are reported, including the observation of psi'-->K_S K_L, psi'--> Vector + Tensor and psi'--> Vector + Pseudoscalar for the measurement of the relative phase between the strong and electromagnetic decays of psi' and a test of the pQCD ``12% rule'' between psi' and J/psi decays; the test of the color-octet mechanism via chi_cJ --> p \bar{p} and chi_cJ-->Λ\barΛ; the first observation of chi_c0--> f_0(980)f_0(980); and a study of the psi' and chi_cJ decays with K_S K_S in the final states.

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