Search

The spontaneous muonium to antimuonium conversion is one of the interesting charged lepton flavor violation processes. It serves as a clear indication of new physics and plays an important role in constraining the parameter space beyond Standard Model. MACE is a proposed experiment to probe such a phenomenon and expected to enhance the sensitivity to the conversion probability by more than two orders of magnitude from the current best upper constraint obtained by the PSI experiment two decades ago. Recent developments in the theoretical and experimental aspects to search for such a rare process are summarized., 13 pages, 10 figures, 3 tables, contribution to Snowmass 2021

Based on the mechanism of neutral meson mixing, we predict the branching fraction of the semileptonic decay of $D_s^+\to \pi^0 \ell^+ \nu_\ell$ ($\ell=e$, $\mu$) using recently measured branching fraction of $D_s^+\to \eta e^+\nu_e$ by BESIII experiment . We also give a formula that can describe the neutral meson mixing of $\pi^0$, $\eta$, $\eta'$ and a pseudoscalar gluonium $G$ in a unified way. The predicted branching fraction of $D_s^+\to\pi^0 e^+\nu_e$ decay is $\mathcal{B}(D_s^+\to\pi^0 e^+\nu_e)=(2.65\pm 0.38)\times 10^{-5}$. It is important to search for the decay $D_s^+\to \pi^0 \ell^+ \nu_\ell$ in experiment, in order to understand the mechanism of $\pi^0$ production in $D_s^+\to\pi^0$ transition in semileptonic decay. We also estimate the branching fraction of $D_s^+\to \pi^0\tau^+\nu_\tau$, which is the only kinematically allowed semi-tauonic decay mode of the charmed meson, since the mass value of $D_s^+$ meson is just slightly above the threshold of $\pi^0\tau^+$ generation in the semi-tauonic decay., Comment: 6 pages, 1 figure

Based on the mechanism of neutral meson mixing, we predict the branching fraction of the semileptonic decay of $D_s^+\to ��^0 \ell^+ ��_\ell$ ($\ell=e$, $��$) using recently measured branching fraction of $D_s^+\to ��e^+��_e$ by BESIII experiment . We also give a formula that can describe the neutral meson mixing of $��^0$, $��$, $��'$ and a pseudoscalar gluonium $G$ in a unified way. The predicted branching fraction of $D_s^+\to��^0 e^+��_e$ decay is $\mathcal{B}(D_s^+\to��^0 e^+��_e)=(2.65\pm 0.38)\times 10^{-5}$. It is important to search for the decay $D_s^+\to ��^0 \ell^+ ��_\ell$ in experiment, in order to understand the mechanism of $��^0$ production in $D_s^+\to��^0$ transition in semileptonic decay. We also estimate the branching fraction of $D_s^+\to ��^0��^+��_��$, which is the only kinematically allowed semi-tauonic decay mode of the charmed meson, since the mass value of $D_s^+$ meson is just slightly above the threshold of $��^0��^+$ generation in the semi-tauonic decay., 6 pages, 1 figure

We study the electromagnetic Dalitz (EM) decays, $��\to ��_{c} l^{+} l^{-}$ and $��\to ��_{b} l^{+} l^{-}$ ($l = e$ or $��$), in which the lepton pair comes from the virtual photon emitted by the M1 transition from $c\bar{c}$ ($b\bar{b}$) spin triplet state to the spin singlet state. We estimate the partial width of $��(��) \to ��_{c}(��_{b}) l^{+} l^{-}$, based on the simple pole approximation. Besides, based on different QCD models, the partial width of $��(��) \to ��_{c}(��_{b}) ��$ is determined.

Using measured branching fraction of the decay $J/\psi \rightarrow\eta Y(2175))\rightarrow\eta\phi f_0(980)\rightarrow\eta\phi\pi^+\pi^{-}$ from the BESIII experiment, we estimate branching fraction of $J/\psi \rightarrow\eta Y(2175))\rightarrow\eta\phi f_0(980)\rightarrow\eta\phi\eta\pi^{0}$ decay, which proceeds via the $f_0(980)$-$a_0^0(980)$ mixing and the $\pi^0$-$\eta$ mixing. The branching fraction is predicted to be about $O(10^{-6})$, which can be accessed with $10^{10}$ $J/\psi$ events collected at the BESIII. The decay is dominated by the contribution from $f_0(980)$-$a_0^0(980)$ mixing. We find that the interference between the amplitudes due to $f_0(980)$-$a_0^0(980)$ mixing and that due to $\pi^0$-$\eta$ mixing is destructive. The branching fraction can be decreased by about $10\%$ owing to the interference effect. We also study the $\eta\pi^0$ mass squared spectrum, and find that a narrow peak due to the $f_0(980)$-$a_0^0(980)$ mixing in the $\eta\pi^0$ mass squared spectrum should be observed. The observation of this decay in experiment will be helpful to determine the $f_0(980)$-$a_0^0(980)$ mixing intensity and get information about the structures of the light scalar mesons., Comment: 16 pages, 3 figures

While indirect and direct CP violation (CPV) has been established in the decays of strange and beauty mesons, no CPV has yet been found for baryons. There are different paths to finding CP asymmetry in the decays of strange baryons; they are all highly non-trivial. The HyperCP Collaboration has probed CPV in the decays of single Ξ and Λ [1]. We discuss future lessons from collisions at BESIII/BEPCII: probing decays of pairs of strange baryons, namely Λ, Σ and Ξ. Realistic goals are to learn about non-perturbative QCD. One can hope to find CPV in the decays of strange baryons; one can also dream of finding the impact of New Dynamics. We point out that an important new era will start with the BESIII/BEPCII data accumulated by the end of 2018. This also supports new ideas to trigger at the LHCb collaboration.

Using measured branching fraction of the decay $J/��\rightarrow��Y(2175))\rightarrow����f_0(980)\rightarrow������^+��^{-}$ from the BESIII experiment, we estimate branching fraction of $J/��\rightarrow��Y(2175))\rightarrow����f_0(980)\rightarrow��������^{0}$ decay, which proceeds via the $f_0(980)$-$a_0^0(980)$ mixing and the $��^0$-$��$ mixing. The branching fraction is predicted to be about $O(10^{-6})$, which can be accessed with $10^{10}$ $J/��$ events collected at the BESIII. The decay is dominated by the contribution from $f_0(980)$-$a_0^0(980)$ mixing. We find that the interference between the amplitudes due to $f_0(980)$-$a_0^0(980)$ mixing and that due to $��^0$-$��$ mixing is destructive. The branching fraction can be decreased by about $10\%$ owing to the interference effect. We also study the $����^0$ mass squared spectrum, and find that a narrow peak due to the $f_0(980)$-$a_0^0(980)$ mixing in the $����^0$ mass squared spectrum should be observed. The observation of this decay in experiment will be helpful to determine the $f_0(980)$-$a_0^0(980)$ mixing intensity and get information about the structures of the light scalar mesons., 16 pages, 3 figures

Within the QCD light-cone sum rule (LCSR) approach, we investigate the transition form factors of $D\rightarrow a_0(980)$ up to the twist-3 light-cone distribution amplitudes (LCDAs) of the scalar meson $a_0(980)$ in the two-quark picture. Using these form factors, we calculate the differential decay widths and branching ratios of the $D\rightarrow a_0(980) e^+ \nu_e$ semileptonic decays. We obtain ${\mathcal B}(D^0\rightarrow a_0^- (980) e^+ \nu_e)=(4.08^{+1.37}_{-1.22})\times 10^{-4}$ and ${\mathcal B}(D^+\rightarrow a_0^0 (980) e^+ \nu_e)=(5.40^{+1.78}_{-1.59})\times 10^{-4}$. The results are sensitive to the $a_0(980)$ inner structure. These decays can be searched for at BESIII experiment, and any experimental observations will be useful to identify internal quark contents of the $a_0(980)$ meson, which will shed light on understanding theoretical models., Comment: 19 pages,5 figures

Within the QCD light-cone sum rule (LCSR) approach, we investigate the transition form factors of $D\rightarrow a_0(980)$ up to the twist-3 light-cone distribution amplitudes (LCDAs) of the scalar meson $a_0(980)$ in the two-quark picture. Using these form factors, we calculate the differential decay widths and branching ratios of the $D\rightarrow a_0(980) e^+ ��_e$ semileptonic decays. We obtain ${\mathcal B}(D^0\rightarrow a_0^- (980) e^+ ��_e)=(4.08^{+1.37}_{-1.22})\times 10^{-4}$ and ${\mathcal B}(D^+\rightarrow a_0^0 (980) e^+ ��_e)=(5.40^{+1.78}_{-1.59})\times 10^{-4}$. The results are sensitive to the $a_0(980)$ inner structure. These decays can be searched for at BESIII experiment, and any experimental observations will be useful to identify internal quark contents of the $a_0(980)$ meson, which will shed light on understanding theoretical models., 19 pages,5 figures

Abundant Ψ' events have been collected at the Beijing Electron Positron Collider- II (BEPCII) that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been noticed before, in the process of J/Ψ decaying to the baryonic final states, pK−, the evident Λ* and N* bands have been observed. Similarly, by using the product of χcJ from Ψ' radiative decay, we may confirm this or find some extra new resonances. χc0's data samples will be more than χc1,2, taking into account the larger branching ratio of Ψ' → γχc0. Here, we provide explicit partial wave analysis formulae for the very interesting channel Ψ' → γχc0 → γpK−.

Decays of both η and η' provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-III. The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of η and η' decays are discussed at BES-III, in which the η and η' mesons are produced in the ψ decays.

We study the branching ratios of D+→D0e+ν,DS+→D0e+ν,BS0→B+e-ν,DS+→D+e-e+ and BS0→B0e-e+ rare semileptonic decay processes,which are induced by decays of light quarks,the heavy quarks remain unchanged.The branching ratios of these decay processes are estimated in the heavy quark limit and with SU(3) ...

A multilayered perceptrons' neural network technique has been applied in the particle identification at BESIII. The networks are trained in each sub-detector level. The NN output of sub-detectors can be sent to a sequential network or be constructed as PDFs for a likelihood. Good muon-ID, electron-ID and hadron-ID are obtained from the networks by using the simulated Monte Carlo samples.

Recently, LHCb experiment announced a 3.5$\sigma$ evidence for direct CP violation in $D^0$ decay by looking at the difference between $A_{CP}(D^0\rightarrow K^+K^-)$ and $A_{CP}(D^0\rightarrow \pi^+\pi^-)$. This is the first evidence of CP violation in 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 opportunity to search for significant contributions from physics beyond the Standard Model. With huge $J/\psi$ and $\psi(2S)$ samples in BESIII experiment, the rare decays may be feasible., Comment: 9 pages, Submitted to Chinese Physics C. arXiv admin note: text overlap with arXiv:0710.0039 by other authors

We study the electromagnetic Dalitz decay modes of $J/\psi \rightarrow P l^+l^-$ ($P= \pi^0$, $\eta$ or $\eta^\prime$). In these decays, the lepton pairs are formed by internal conversion of an intermediate virtual photon with invariant mass $m_{l^+l^-}$. Study of the effective-mass spectrum of the $l^+l^-$ will shed light on the dynamic transition form factor $F_{J/\psi P}(q^2)$ ($q^2 = m^2_{l^+l^-}$), which characterizes the electromagnetic structure arising at the vertex of the transition $J/\psi$ to pseudoscalars. We also discuss the direct productions of a GeV scale vector $U$ boson in these processes $J/\psi \rightarrow PU$ ($U\rightarrow l^+l^-$). It is responsible for mediating a new $U(1)_d$ interaction, as recently exploited in the context of weakly interacting massive particle dark matter. In this paper, we firstly use the usual pole approximation for the form factor to estimate the decay rate of $J/\psi \rightarrow P l^+l^-$ in the standard model. Then the reach of searching for the dark photon is estimated. We suggest that these Dalitz decays can be used to search for the light $U$ boson in the BESIII experiment with a huge $J/\psi$ data set., Comment: 6 pages, 3 figure, add two more figures, more discussions

We have analyzed the $D\rightarrow \pi K, KK$ decay with the naive factorization (NF), QCD factorization (QCDF)and QCD factorization including soft-gluon exchanges (QCDF+SGE). In these decay channels, the soft-gluon effects are firstly calculated with light cone QCD sum rules. Comparing the three kind approaches, we can find the calculation results have made much more improved QCD factorization (QCDF) than the naive factorization (NF), and the calculation results have also made improved QCD factorization including soft-gluon exchanges (QCDF+SGE) than the QCD factorization (QCDF) in the color-suppressed decay channels. In addition, we find the soft-gluon effects are larger than the leading order contributions, and the calculation results are close to the experimental data for the color-suppressed decay channels. In color-allowed decay channel $D^{0}\rightarrow \pi^{+} K^{-}$, the soft-gluon effects are small and we should consider other power terms, such as final state interaction and annihilation effects.

We study the electromagnetic Dalitz decay modes of $J/��\rightarrow P l^+l^-$ ($P= ��^0$, $��$ or $��^\prime$). In these decays, the lepton pairs are formed by internal conversion of an intermediate virtual photon with invariant mass $m_{l^+l^-}$. Study of the effective-mass spectrum of the $l^+l^-$ will shed light on the dynamic transition form factor $F_{J/��P}(q^2)$ ($q^2 = m^2_{l^+l^-}$), which characterizes the electromagnetic structure arising at the vertex of the transition $J/��$ to pseudoscalars. We also discuss the direct productions of a GeV scale vector $U$ boson in these processes $J/��\rightarrow PU$ ($U\rightarrow l^+l^-$). It is responsible for mediating a new $U(1)_d$ interaction, as recently exploited in the context of weakly interacting massive particle dark matter. In this paper, we firstly use the usual pole approximation for the form factor to estimate the decay rate of $J/��\rightarrow P l^+l^-$ in the standard model. Then the reach of searching for the dark photon is estimated. We suggest that these Dalitz decays can be used to search for the light $U$ boson in the BESIII experiment with a huge $J/��$ data set., 6 pages, 3 figure, add two more figures, more discussions

BESIII had collected large data samples on $J/\psi$ and $\psi^\prime$ peaks during the first run in 2009. From 2010 to 2011, about 2.9 fb$^{-1}$ integrated luminosity were obtained on the peak of $\psi(3770)$ for open charm physics. We review recent results on charmonium decays and hadron spectroscopy. The prospects on open charm physics are also discussed., Comment: 14 pages, 11 figures, Proceeding for XIV International Conference on Hadron Spectroscopy (hadron2011), 13-17 June 2011, Munich, Germany

We have analyzed the $D\rightarrow ��K, KK$ decay with the naive factorization (NF), QCD factorization (QCDF)and QCD factorization including soft-gluon exchanges (QCDF+SGE). In these decay channels, the soft-gluon effects are firstly calculated with light cone QCD sum rules. Comparing the three kind approaches, we can find the calculation results have made much more improved QCD factorization (QCDF) than the naive factorization (NF), and the calculation results have also made improved QCD factorization including soft-gluon exchanges (QCDF+SGE) than the QCD factorization (QCDF) in the color-suppressed decay channels. In addition, we find the soft-gluon effects are larger than the leading order contributions, and the calculation results are close to the experimental data for the color-suppressed decay channels. In color-allowed decay channel $D^{0}\rightarrow ��^{+} K^{-}$, the soft-gluon effects are small and we should consider other power terms, such as final state interaction and annihilation effects.

We exploit the angular and quantum correlations in the $D\bar{D}$ pairs produced through the decay of the $\psi(3770)$ resonance in a charm factory to investigate CP-violation in two different ways. We consider the case of $\psi(3770)\rightarrow D\bar{D}\rightarrow (V_1V_2)(K\pi)$ decays, which provide a new way to measure the strong phase difference $\delta$ between Cabibbo-favored and doubly-Cabibbo suppressed $D$ decays required in the determination of the CKM angle $\gamma$. We also build CP-violating observables in $\psi(3770)\rightarrow D\bar{D}\rightarrow (V_1V_2)(V_3 V_4)$ to isolate specific new physics effects in the charm sector. Neglecting the systematics, we give a first rough estimate of the sensitivities of these measurements at BES-III with an integrated luminosity of 20 fb$^{-1}$ at $\psi(3770)$ peak and at a future super $\tau$-charm factory with a luminosity of $10^{35}$ cm$^{-2}$s$^{-1}$, Comment: 4 pages, in Pos style, Proceeding for ICHEP2010, Paris

We exploit the angular and quantum correlations in the $D\bar{D}$ pairs produced through the decay of the $��(3770)$ resonance in a charm factory to investigate CP-violation in two different ways. We consider the case of $��(3770)\rightarrow D\bar{D}\rightarrow (V_1V_2)(K��)$ decays, which provide a new way to measure the strong phase difference $��$ between Cabibbo-favored and doubly-Cabibbo suppressed $D$ decays required in the determination of the CKM angle $��$. We also build CP-violating observables in $��(3770)\rightarrow D\bar{D}\rightarrow (V_1V_2)(V_3 V_4)$ to isolate specific new physics effects in the charm sector. Neglecting the systematics, we give a first rough estimate of the sensitivities of these measurements at BES-III with an integrated luminosity of 20 fb$^{-1}$ at $��(3770)$ peak and at a future super $��$-charm factory with a luminosity of $10^{35}$ cm$^{-2}$s$^{-1}$, 4 pages, in Pos style, Proceeding for ICHEP2010, Paris

In this paper, we study CP violation in $��_c^+\to BP$ and $��_c^+\to BV$ decays, where $B,P$ and $V$ denote a light spin-1/2 baryon, pseudoscalar and a vector meson respectively. In these processes the $T$ odd CP violating triple-product (TP) correlations are examined. The genuine CP violating observables which are composed of the helicity amplitudes occurring in the angular distribution are constructed. Experimentally, by performing a full angular analysis it is shown how one may extract the helicity amplitudes and then obtain the TP asymmetries. We estimate the TP asymmetries in $\lam$ decays to be negligible in the standard model making these processes an excellent place to look for new physics. Taking a two Higgs doublet model, as an example of new physics, we show that large TP asymmetries are possible in these decays. Finally, we discuss how BES-III and Super $��$-Charm experiments will be sensitive to these CP violating signals in $��_c^+$ decays., 7 pages, 2 tables. Journal reference is added

The abundant $\psi'$ events have been collected at the Beijing Electron Positron Collider-II (BEPCII) that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been noticed before, in the process of $J/\psi$ decaying to the baryonic final states, $p K^- \bar{\Lambda}$, the evident $\Lambda^*$ and $N^*$ bands have been observed. Similarly, by using the product of $\chi_{cJ}$ from $\psi'$ radiative decay, we may confirm it or find some extra new resonances. $\chi_{c0}$'s data samples will be more than $\chi_{c1,2}$ taking into account the larger branching ratio of $\psi'\to\gamma\chi_{c0}$. Here, we provide explicit partial wave analysis formulae for the very interesting channel $\psi'\to\gamma\chi_{c0}\to \gamma p K^- \bar{\Lambda}$., Comment: 7 pages, 1 figure, version in Chin.Phys.C

Based on the data of BES and Belle, the production of $D\bar{D}$ in the $e^+e^-\to D\bar{D}$ scattering process is studied in this paper. We analyze the continuum and resonant contributions in the energy region from 3.7 to 4.4 GeV. In the $\chi^2$ fit to data, we obtain the resonance parameters of $\psi(3770)$, the branching ratio of $\psi(3770)\to D\bar{D}$ decay by confronting the data to the theoretical formula where both the contributions of the resonances, continuum and interference effects are included. We obtain the branching ratio of $\psi(3770)\to D\bar{D}$ decay is $97.2%\pm 8.9%$, as well as the branching ratio of $\psi(4040)$, $\psi(4160)\to D\bar{D}$ decays., Comment: 6 pages, 1 figure, 1 table, version to appear in Phys. Rev. D Rapid communications

Decays of both $\eta$ and $\eta^\prime$ provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-III. The rare decays of the $\eta$ and $\eta^\prime$ mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of $\eta$ and $\eta^\prime$ decays are discussed at BES-III, in which the $\eta$ and $\eta^\prime$ mesons are produced in the $\psi$ decays., Comment: A few corrections added, published at J. Phys. G: Nucl. Part. Phys

The abundant $��'$ events have been collected at the Beijing Electron Positron Collider-II (BEPCII) that could undoubtedly provide us with a great opportunity to study the more attractive charmonium decays. As has been noticed before, in the process of $J/��$ decaying to the baryonic final states, $p K^- \bar��$, the evident $��^*$ and $N^*$ bands have been observed. Similarly, by using the product of $��_{cJ}$ from $��'$ radiative decay, we may confirm it or find some extra new resonances. $��_{c0}$'s data samples will be more than $��_{c1,2}$ taking into account the larger branching ratio of $��'\to����_{c0}$. Here, we provide explicit partial wave analysis formulae for the very interesting channel $��'\to����_{c0}\to ��p K^- \bar��$., 7 pages, 1 figure, version in Chin.Phys.C

Decays of both $��$ and $��^\prime$ provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-III. The rare decays of the $��$ and $��^\prime$ mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of $��$ and $��^\prime$ decays are discussed at BES-III, in which the $��$ and $��^\prime$ mesons are produced in the $��$ decays., A few corrections added, published at J. Phys. G: Nucl. Part. Phys

Based on the data of BES and Belle, the production of $D\bar{D}$ in the $e^+e^-\to D\bar{D}$ scattering process is studied in this paper. We analyze the continuum and resonant contributions in the energy region from 3.7 to 4.4 GeV. In the $��^2$ fit to data, we obtain the resonance parameters of $��(3770)$, the branching ratio of $��(3770)\to D\bar{D}$ decay by confronting the data to the theoretical formula where both the contributions of the resonances, continuum and interference effects are included. We obtain the branching ratio of $��(3770)\to D\bar{D}$ decay is $97.2%\pm 8.9%$, as well as the branching ratio of $��(4040)$, $��(4160)\to D\bar{D}$ decays., 6 pages, 1 figure, 1 table, version to appear in Phys. Rev. D Rapid communications

In this paper, we intend to study the problem of CP violation in $D$ meson by $D\to VV$ decay mode in which the T violating triple-product correlation is examined. That would undoubtedly be another excellent probe of New Physics beyond Standard Model. For the neutral $D$, we focus on direct CP violation without considering $D^0-\bar D^0$ oscillation. Experimentally, by a full angular analysis one may obtain such CP violating signals, and particularly it is worth mentioning that the upcoming large $D$ data samples at BES-III in Beijing will provide a great opportunity to perform it., 5 pages, 2 tables and 1 figure, version to appear in Phys. Lett. B

We established a method on measuring the $\dzdzb$ mixing parameter $y$ for BESIII experiment at the BEPCII $e^+e^-$ collider. In this method, the doubly tagged $\psi(3770) \to D^0 \overline{D^0}$ events, with one $D$ decays to CP-eigenstates and the other $D$ decays semileptonically, are used to reconstruct the signals. Since this analysis requires good $e/\pi$ separation, a likelihood approach, which combines the $dE/dx$, time of flight and the electromagnetic shower detectors information, is used for particle identification. We estimate the sensitivity of the measurement of $y$ to be 0.007 based on a $20fb^{-1}$ fully simulated MC sample., Comment: 6 pages, 7 figures

The recent observations of the purely leptonic decay $\Ds \to \mu^+ \nu_{\mu}$ and $\tau^+\nu_{\tau}$ at CLEO-c and $B$ factory may allow a possible contribution from a charged Higgs boson. One such measurement of the decay constant $f_{D_s}$ differs from the most precise unquenched lattice QCD calculation by 4 $\sigma$ level. Meanwhile, the measured ratio, ${\cal BR}(\Ds \to \mu^+ \nu_{\mu})$ / ${\cal BR}(\Dp \to \mu^+ \nu_{\mu})$, is larger than the standard model prediction at 2.0$\sigma$ level. We discuss that the precise measurement of the ratio ${\cal BR}(\Ds \to \mu^+ \nu_{\mu})$ / ${\cal BR}(\Dp \to \mu^+ \nu_{\mu})$ at BES-III will shed light on the presence of new intermediate particles by comparing the theoretical predictions, especially, the predictions of high precise unquenched lattice QCD calculation., Comment: 5 pages, 3 figures, mini-review, accepted by Chinese Physics C (HEP & NP)

This paper presents the results of searches for the flavor-changing neutral current, lepton-number-violating and lepton-flavor-violating processes in the charm mesons decays. Recent results from charged $D$ mesons decays to final states with dielectrons from CLEO-c are reported. The prospects of the searches for the rare charm decays at BES-III are also discussed., Add more reference; 10 pages, 1 figure. Contribution to KAON International Conference, May 21-25 2007, Laboratori Nazionali di Frascati dell'INFN, Rome, Italy

Questions about detecting CP-violating decay process of $J/\psi\to K^0\bar{K}^0\to K_SK_S$ are discussed. Possible background and material regeneration effect are analyzed. The discussion can be directly extended to other vector quarkonium decays, like $\Upsilon$, $\psi (2S)$ and $\phi\to K_S K_S$., Comment: 5 pages, 2 figures, Latex

The Circular Electron Positron Collider (CEPC) is a large international scientific facility proposed by the Chinese particle physics community to explore the Higgs boson and provide critical tests of the underlying fundamental physics principles of the Standard Model that might reveal new physics. The CEPC, to be hosted in China in a circular underground tunnel of approximately 100 km in circumference, is designed to operate as a Higgs factory producing electron-positron collisions with a center-of-mass energy of 240 GeV. The collider will also operate at around 91.2 GeV, as a Z factory, and at the WW production threshold (around 160 GeV). The CEPC will produce close to one trillion Z bosons, 100 million W bosons and over one million Higgs bosons. The vast amount of bottom quarks, charm quarks and tau-leptons produced in the decays of the Z bosons also makes the CEPC an effective B-factory and tau-charm factory. The CEPC will have two interaction points where two large detectors will be located. This document is the second volume of the CEPC Conceptual Design Report (CDR). It presents the physics case for the CEPC, describes conceptual designs of possible detectors and their technological options, highlights the expected detector and physics performance, and discusses future plans for detector R&D and physics investigations. The final CEPC detectors will be proposed and built by international collaborations but they are likely to be composed of the detector technologies included in the conceptual designs described in this document. A separate volume, Volume I, recently released, describes the design of the CEPC accelerator complex, its associated civil engineering, and strategic alternative scenarios., 424 pages