Publications (342)1079.37 Total impact
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ABSTRACT: From 2011 to 2014, the BESIII experiment collected about 5 fb$^{1}$ data at centerofmass energies around 4 GeV for the studies of the charmoniumlike and higher excited charmonium states. By analyzing the dimuon process $e^{+}e^{}\rightarrow\gamma_{\rm ISR/FSR}\mu^{+}\mu^{}$, the centerofmass energies of the data samples are measured with a precision of 0.8 MeV. The centerofmass energy is found to be stable for most of time during the data taking.  [Show abstract] [Hide abstract]
ABSTRACT: Using 2.92~fb$^{1}$ of electronpositron annihilation data collected at $\sqrt{s} = 3.773$~GeV with the BESIII detector, we obtain the first measurements of the absolute branching fraction $\mathcal{B}(D^+ \to K^0_L e^+ \nu_e) = (4.481 \pm 0.027(\mathrm{stat.}) \pm 0.103(\mathrm{sys.}))\%$ and the $CP$ asymmetry $A_{CP}^{D^+ \to K^0_L e^+ \nu_e} = (0.59 \pm 0.60(\mathrm{stat.}) \pm 1.48(\mathrm{sys.}))\%$. From the $D^+ \to K^0_L e^+ \nu_e$ differential decay rate distribution, the product of the hadronic form factor and the magnitude of the CKM matrix element, $f_{+}^{K}(0)V_{cs}$, is determined to be $0.728 \pm 0.006(\mathrm{stat.}) \pm 0.011(\mathrm{sys.})$. Using $V_{cs}$ from the SM constrained fit with the measured $f_{+}^{K}(0)V_{cs}$, $f_{+}^{K}(0) = 0.748 \pm 0.007(\mathrm{stat.}) \pm 0.012(\mathrm{sys.})$ is obtained, and utilizing the unquenched LQCD calculation for $f_{+}^{K}(0)$, $V_{cs} = 0.975 \pm 0.008(\mathrm{stat.}) \pm 0.015(\mathrm{sys.}) \pm 0.025(\mathrm{LQCD})$.  [Show abstract] [Hide abstract]
ABSTRACT: The spinorbit coupling (SOC) in the 5d transition metal element is expected to be strong due to the large atomic number and ability to modify the electronic structure drastically. On the other hand, the Coulomb interaction in 5d transition is nonnegligible. Hence, the interplay of electron correlations and strong spinorbit interactions make the 5d transition metal oxides (TMOs) specially interesting for possible novel properties. In this paper, we briefly summarize our theoretical studies on the 5d TMO. In section 2, we systematically discuss pyrochlore iridates. We find that magnetic moments at Ir sites form a noncolinear pattern with moment on a tetrahedron pointing to allin or allout from the center. We propose that pyrochlore iridates be Weyl Semimetal (WSM), thus providing a condensedmatter realization of Weyl fermion that obeys a twocomponent Dirac equation. We find that Weyl points are robust against perturbation and further reveal that WSM exhibits remarkable topological properties manifested by surface states in the form of Fermi arcs, which is impossible to realize in purely twodimensional band structures. In section 3, based on density functional calculation, we predict that spinel osmates (AOs2O4, A= Ca, Sr) show a large magnetoelectric coupling characteristic of axion electrodynamics. They show ferromagnetic order in a reasonable range of the onsite Coulomb correlation U and exotic electronic properties, in particular, a large magnetoelectric coupling characteristic of axion electrodynamics. Depending on U, other electronic phases including a 3D WSM and Mott insulator are also shown to occur. In section 4, we comprehensively discuss the electronic and magnetic properties of Slater insulator NaOsO3, and successfully predict the magnetic ground state configuration of this compound. Its ground state is of a Gtype antiferromagnet, and it is the combined effect of U and magnetic configuration that results in the insulating behavior of NaOsO3 We also discuss the novel properties of LiOsO3, and suggest that the highly anisotropic screening and the local dipoledipole interactions are the two most important keys to forming LiOsO3type metallic ferroelectricity in section 5. Using densityfunctional calculations, we systematically study the origin of the metallic ferroelectricity in LiOsO3. We confirm that the ferroelectric transition in this compound is orderdisorderlike. By doing electron screening analysis, we unambiguously demonstrate that the longrange ferroelectric order in LiOsO3 results from the incomplete screening of the dipoledipole interaction along the nearestneighboring LiLi chain direction.  [Show abstract] [Hide abstract]
ABSTRACT: A neutral structure in the $D\bar{D}^{*}$ system around the $D\bar{D}^{*}$ mass threshold is observed with a statistical significance greater than 10$\sigma$ in the processes $e^{+}e^{}\rightarrow D^{+}D^{*}\pi^{0}+c.c.$ and $e^{+}e^{}\rightarrow D^{0}\bar{D}^{*0}\pi^{0}+c.c.$ at $\sqrt{s}$ = 4.226 and 4.257 GeV in the BESIII experiment. The structure is denoted as $Z_{c}(3885)^{0}$. Assuming the presence of a resonance, its pole mass and width are determined to be ($3885.7^{+4.3}_{5.7}$(stat.)$\pm 8.4$(syst.))~MeV/$c^{2}$ and ($35^{+11}_{12}$(stat.)$ \pm 15$(syst.))~MeV, respectively. The Born cross sections are measured to be $\sigma(e^{+}e^{}\to Z_{c}(3885)^{0}\pi^{0}, Z_{c}(3885)^{0} \to D\bar{D}^{*})=(77 \pm 13$(stat.)$\pm 17$(syst.)) pb at 4.226 GeV and ($47 \pm 9$(stat.)$ \pm 10$(syst.)) pb at 4.257 GeV. The ratio of decay rates $\frac{\mathcal{B}({Z_{c}(3885)^{0} \to D^{+}D^{*}+c.c.})}{\mathcal{B}({Z_{c}(3885)^{0} \to D^{0}\bar{D}^{*0}+c.c.})}$ is determined to be $0.96 \pm 0.18$(stat.)$\pm 0.12$(syst.), consistent with no isospin violation in the process $Z_{c}(3885)^{0}\to D\bar{D}^*$.  [Show abstract] [Hide abstract]
ABSTRACT: We report an observation of the process J/ψ→γX(1835)→γK_{S}^{0}K_{S}^{0}η at low K_{S}^{0}K_{S}^{0} mass with a statistical significance larger than 12.9σ using a data sample of 1.31×10^{9} J/ψ events collected with the BESIII detector. In this region of phase space the K_{S}^{0}K_{S}^{0} system is dominantly produced through the f_{0}(980). By performing a partial wave analysis, we determine the spin parity of the X(1835) to be J^{PC}=0^{+}. The mass and width of the observed X(1835) are 1844±9(stat)_{25}^{+16}(syst) MeV/c^{2} and 192_{17}^{+20}(stat)_{43}^{+62}(syst) MeV, respectively, which are consistent with the results obtained by BESIII in the channel J/ψ→γπ^{+}π^{}η^{'}.Physical Review Letters 09/2015; 115(9):091803. · 7.51 Impact Factor 
Article: Observation of η ′ → ω e + e
Physical Review D 09/2015; 92(5). DOI:10.1103/PhysRevD.92.051101 · 4.64 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present a study of the process $e^+e^\to\pi^{\pm}(D\bar{D}^*)^{\mp}$ using data samples of 1092 pb$^{1}$ at $\sqrt{s}=4.23$ GeV and 826 pb$^{1}$ at $\sqrt{s}=4.26$ GeV collected with the BESIII detector at the BEPCII storage ring. With full reconstruction of the $D$ meson pair and the bachelor $\pi^{\pm}$ in the final state, we confirm the existence of the charged structure $Z_c(3885)^{\mp}$ in the $(D\bar{D}^*)^{\mp}$ system in the two isospin processes $e^+e^\to\pi^+D^0D^{*}$ and $e^+e^\to\pi^+D^D^{*0}$. By performing a simultaneous fit, the statistical significance of $Zc(3885)^{\mp}$ signal is determined to be greater than 10$\sigma$, and its pole mass and width are measured to be $M_{\rm{pole}}$=(3881.7$\pm$1.6(stat.)$\pm$2.1(syst.)) MeV/$c^2$ and $\Gamma_{\rm{pole}}$=(26.6$\pm$2.0(stat.)$\pm$2.3(syst.)) MeV, respectively. The Born cross section times the $(D\bar{D}^*)^{\mp}$ branching fraction ($\sigma(e^+e^\to\pi^{\pm}Z_{c}(3885)^{\mp}) \times Br(Z_{c}(3885)^{\mp}\to(D\bar{D}^*)^{\mp})$) is measured to be $(141.4\pm7.9(\text{stat.})\pm12.8(\text{syst.})) \text{pb}$ at $\sqrt{s}=4.23$ GeV and $(108.4\pm6.9(\text{stat.})\pm9.1(\text{syst.})) \text{pb}$ at $\sqrt{s}=4.26$ GeV. The polar angular distribution of the $\pi^{\pm}$$Z_c(3885)^{\mp}$ system is consistent with the expectation of a quantum number assignment of $J^P=1^+$ for $Z_c(3885)^{\mp}$.  [Show abstract] [Hide abstract]
ABSTRACT: In an analysis of a 2.92~fb$^{1}$ data sample taken at 3.773~GeV with the BESIII detector operated at the BEPCII collider, we measure the absolute decay branching fractions to be $\mathcal B(D^0 \to K^e^+\nu_e)=(3.505\pm 0.014 \pm 0.033)\%$ and $\mathcal B(D^0 \to \pi^e^+\nu_e)=(0.295\pm 0.004\pm 0.003)\%$. From a study of the differential decay rates we obtain the products of hadronic form factor and the magnitude of the CKM matrix element $f_{+}^K(0)V_{cs}=0.7172\pm0.0025\pm 0.0035$ and $f_{+}^{\pi}(0)V_{cd}=0.1435\pm0.0018\pm 0.0009$. Combining these products with the values of $V_{cs(d)}$ from the SM constraint fit, we extract the hadronic form factors $f^K_+(0) = 0.7368\pm0.0026\pm 0.0036$ and $f^\pi_+(0) = 0.6372\pm0.0080\pm 0.0044$, and their ratio $f_+^{\pi}(0)/f_+^{K}(0)=0.8649\pm 0.0112\pm 0.0073$. These form factors and their ratio are used to test unquenched Lattice QCD calculations of the form factors and a light cone sum rule (LCSR) calculation of their ratio. The measured value of $f_+^{K(\pi)}(0) V_{cs(d)}$ and the lattice QCD value for $f^{K(\pi)}_+(0)$ are used to extract values of the CKM matrix elements of $V_{cs}=0.9601 \pm 0.0033 \pm 0.0047 \pm 0.0239$ and $V_{cd}=0.2155 \pm 0.0027 \pm 0.0014 \pm 0.0094$, where the third errors are due to the uncertainties in lattice QCD calculations of the form factors. Using the LCSR value for $f_+^\pi(0)/f_+^K(0)$, we determine the ratio $V_{cd}/V_{cs}=0.238\pm 0.004\pm 0.002\pm 0.011$, where the third error is from the uncertainty in the LCSR normalization. In addition, we measure form factor parameters for three different theoretical models that describe the weak hadronic charged currents for these two semileptonic decays. All of these measurements are the most precise to date.  [Show abstract] [Hide abstract]
ABSTRACT: Charge dipole moment and spin moment rarely coexist in singlephase bulk materials except in some multiferroics. Despite the progress in the past decade, for most multiferroics their magnetoelectric performance remains poor due to the intrinsic exclusion between charge dipole and spin moment. As an alternative approach, the oxide heterostructures may evade the intrinsic limits in bulk materials and provide more attractive potential to realize the magnetoelectric functions. Here we perform a firstprinciples study on LaAlO$_3$/PbTiO$_3$ superlattices. Although neither of the components is magnetic, magnetic moments emerge at the ferroelectric domain walls of PbTiO$_3$ in these superlattices. Such a twist between ferroelectric domain and local magnetic moment, not only manifests an interesting type of multiferroicity, but also is possible useful to pursuit the electricalcontrol of magnetism in nanoscale heterostructures.Scientific Reports 08/2015; 5. DOI:10.1038/srep13052 · 5.58 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Using 2.92 fb$^{1}$ of electronpositron annihilation data collected at a centerofmass energy of $\sqrt{s}= 3.773$ GeV with the BESIII detector, we present an improved measurement of the branching fraction $\mathcal{B}(D^+ \to \omega e^+ \nu_{e}) = (1.63\pm0.11\pm0.08)\times 10^{3}$. The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time, we measure them to be $r_V = 1.24\pm0.09\pm0.06$ and $r_2 = 1.06\pm0.15 \pm 0.05$. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay $D^+ \to \phi e^+ \nu_{e}$. An improved upper limit $\mathcal{B}(D^+ \to \phi e^+ \nu_{e}) < 1.3 \times 10^{5}$ is set at 90\% confidence level.  [Show abstract] [Hide abstract]
ABSTRACT: We extract the $e^+e^\rightarrow \pi^+\pi^$ cross section in the energy range between 600 and 900 MeV, exploiting the method of initial state radiation. A data set with an integrated luminosity of 2.93 fb$^{1}$ taken at a centerofmass energy of 3.773 GeV with the BESIII detector at the BEPCII collider is used. The cross section is measured with a systematic uncertainty of 0.9%. We extract the pion form factor $F_\pi^2$ as well as the contribution of the measured cross section to the leading order hadronic vacuum polarization contribution to $(g2)_\mu$. We find this value to be $a_\mu^{\pi\pi,\rm LO}(600900\;\rm MeV) = (372.5 \pm 2.6_{\rm stat} \pm 3.4_{\rm sys})\cdot 10^{10}$.  [Show abstract] [Hide abstract]
ABSTRACT: We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process $e^+e^\rightarrow \pi\pi X$. These asymmetries can be attributed to the Collins fragmentation function, which describes the behavior of a hadron produced from a transversely polarized quark. This work is performed using a data set of 62 $\rm{pb}^{1}$ at the centerofmass energy $\sqrt{s}=3.65$ GeV collected with the BESIII detector at the BEPCII storage rings, where the corresponding fourmomentum transfer of the virtual photon, $Q^2$, is close to the energy scale of the existing semiinclusive DIS experimental data. We observe a nonzero asymmetry, which increases with increasing pion momentum and also indicates a larger spindependent Collins effect than at higher energy scale. The dependence of the asymmetry on the transverse momentum of hadrons to the reference axis is also investigated. The measured asymmetries are important inputs for the global analysis of extracting the quark transversity distribution inside the nucleon, and are valuable to explore the energy evolution of the spindependent fragmentation function.  [Show abstract] [Hide abstract]
ABSTRACT: Based on a sample of \etapr mesons produced in the radiative decay $J/\psi\to\gamma\eta^{\prime}$ in $1.31\times 10^9$ $J/\psi$ events collected with the BESIII detector, the decay $\eta^{\prime}\to\omega e^{+} e^{}$ is observed for the first time, with a statistical significance of $8\sigma$. The branching fraction is measured to be $\mathcal{B}(\eta^{\prime}\to\omega e^{+} e^{})=(1.97\pm0.34(\text{stat})\pm0.17(\text{syst}))\times10^{4}$, which is in agreement with theoretical predictions. The branching fraction of $\eta^{\prime}\to\omega\gamma$ is also measured to be $(2.55\pm0.03(\text{stat})\pm0.16(\text{syst}))\times10^{2}$, which is the most precise measurement to date, and the relative branching fraction $\frac{\mathcal{B}(\eta^{\prime}\to \omega e^{+}e^{})}{\mathcal{B}(\eta^{\prime}\to \omega \gamma)}$ is determined to be $(7.71\pm1.34(\text{stat})\pm0.54(\text{syst}))\times10^{3}$.  [Show abstract] [Hide abstract]
ABSTRACT: We report the observation of the X(3823) state in the process e^{+}e^{}→π^{+}π^{}X(3823)→π^{+}π^{}γχ_{c1} with a statistical significance of 6.2σ, in data samples at centerofmass energies sqrt[s]=4.230, 4.260, 4.360, 4.420, and 4.600 GeV collected with the BESIII detector at the BEPCII electron positron collider. The measured mass of the X(3823) state is (3821.7±1.3±0.7) MeV/c^{2}, where the first error is statistical and the second systematic, and the width is less than 16 MeV at the 90% confidence level. The products of the Born cross sections for e^{+}e^{}→π^{+}π^{}X(3823) and the branching ratio B[X(3823)→γχ_{c1,c2}] are also measured. These measurements are in good agreement with the assignment of the X(3823) state as the ψ(1 ^{3}D_{2}) charmonium state.Physical Review Letters 07/2015; 115(1):011803. · 7.51 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We report a study of the process $e^{+} e^{} \to (D^{*} \bar{D}^{*})^{0} \pi^0$ using $e^+e^$ collision data samples with integrated luminosity of $1092 \rm{pb}^{1}$ at $\sqrt{s}=4.23 \rm{GeV}$ and $826 \rm{pb}^{1}$ at $\sqrt{s}=4.26 \rm{GeV}$ collected with the BESIII detector at the BEPCII storage ring. We observe a new neutral structure near the $(D^{*} \bar{D}^{*})^{0}$ mass threshold in the $\pi^0$ recoil mass spectrum, which we denote as $Z_{c}(4025)^{0}$. Assuming a BreitWigner line shape, its pole mass and pole width are determined to be $(4025.5^{+2.0}_{4.7}\pm3.1) \rm{MeV}/c^2$ and $(23.0\pm 6.0\pm 1.0) \rm{MeV}$, respectively. The statistical significance of the observation is $7.4\sigma$. The Born cross sections of $e^{+}e^{}\to Z_{c}(4025)^{0} \pi^0\to (D^{*} \bar{D}^{*})^{0}\pi^0$ are measured to be $(61.6\pm8.2\pm9.0) \rm{pb}$ at $\sqrt{s}=4.23 \rm{GeV}$ and $(43.4\pm8.0\pm5.4) \rm{pb}$ at $\sqrt{s}=4.26 \rm{GeV}$. The first uncertainties are statistical and the second are systematic.  [Show abstract] [Hide abstract]
ABSTRACT: The decay $Z_c(3900)^\pm\to\omega\pi^\pm$ is searched for using data samples collected with the BESIII detector operating at the BEPCII storage ring at centerofmass energies $\sqrt{s}=4.23$ and $4.26$~GeV. No significant signal for the $Z_c(3900)^\pm$ is found, and upper limits at the 90\% confidence level on the Born cross section for the process $e^+e^\to Z_c(3900)^\pm\pi^\mp\to\omega\pi^+\pi^$ are determined to be $0.26$ and $0.18$ pb at $\sqrt{s}=4.23$ and 4.26 GeV, respectively.  [Show abstract] [Hide abstract]
ABSTRACT: We study $D_{s}^{+}$ decays to final states involving the $\eta'$ with a 482\,pb$^{1}$ data sample collected at $\sqrt{s}$ = 4.009\,GeV with the \mbox{BESIII} detector at the BEPCII collider. We measure the branching fractions $\mathcal{B}(D^+_{s}\rightarrow \eta'X)$ = (8.8$\pm$1.8$\pm$0.5)\% and $\mathcal{B}(D_{s}^{+}\rightarrow \eta'\rho^{+})$ = ($5.8\pm1.4\pm0.4$)\% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the nonresonant branching ratio $\mathcal{B}(D_{s}^{+}\rightarrow \eta'\pi^+\pi^0)<5.1\%$ at the 90\% confidence level. Our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of $\mathcal{B}(D_{s}^{+}\rightarrow \eta'\rho^{+})$.Physics Letters B 06/2015; 750. DOI:10.1016/j.physletb.2015.09.059 · 6.13 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Based on a sample of $1.31 \times 10^9$ $J/\psi$ events collected with the BESIII detector at the BEPCII collider, Dalitz plot analyses of selected 79,625 $\eta\rightarrow\pi^{+}\pi^{}\pi^0$ events, 33,908 $\eta\rightarrow\pi^0\pi^0\pi^0$ events and 1,888 $\eta^{\prime}\rightarrow\pi^0\pi^0\pi^0$ events are performed. The measured matrix elements of $\eta\rightarrow\pi^+\pi^\pi^0$ are in reasonable agreement with previous measurements. The Dalitz plot slope parameters of $\eta\rightarrow\pi^0\pi^0\pi^0$ and $\eta^{\prime}\rightarrow\pi^0\pi^0\pi^0$ are determined to be $0.055 \pm 0.014 \pm 0.004$ and $0.640 \pm 0.046 \pm 0.047$, respectively, where the first uncertainties are statistical and the second systematic. Both values are consistent with previous measurements, while the precision of the latter one is improved by a factor of three. Final state interactions are found to have an important role in those decays.  [Show abstract] [Hide abstract]
ABSTRACT: The Casimir effect is a general phenomenon in physics, which arises when the vacuum fluctuation of an arbitrary field is modified by static or slowly varying boundary. However, its spin version is rarely addressed, mainly due to the fact that a macroscopic boundary in quantum spin systems is hard to define. In this article, we explore the spin Casimir effect induced by the zeropoint fluctuation of spin waves in a general noncollinear ordered quantum antiferromagnet. This spin Casimir effect results in a spin torque between local spins and further causes various singular and divergent results in the framework of spinwave theory, which invalidate the standard $1/S$ expansion procedure. To avoid this dilemma, we develop a selfconsistent spinwave expansion approach, which preserves the spinwave expansion away from singularities and divergence. A detailed spinwave analysis of the antiferromagnetic spin1/2 Heisenberg model on a spatially anisotropic triangular lattice is undertaken within our approach. Our results indicate that the spiral order is only stable in the region $0.5<\alpha<1.2$, where $\alpha$ is the ratio of the coupling constants. In addition, the instability in the region $1.2<\alpha<2$ is owing to the spin Casimir effect instead of the vanishing sublattice magnetization. And this extended spiral instable region may host some quantum disordered phases besides the quantum order by disorder induced Neel phase. Furthermore, our method provides an efficient and convenient tool that can estimate the correct exchange parameters and outline the quantum phase diagrams, which can be useful for experimental fitting processes in frustrated quantum magnets.  [Show abstract] [Hide abstract]
ABSTRACT: We report an observation of the process $J/\psi\rightarrow\gamma X(1835)\rightarrow\gamma K^0_S K^0_S\eta$ at low $K^0_S K^0_S$ mass with a statistical significance larger than 12.9$\sigma$ using a data sample of $1.31 \times 10^{9}$ $J/\psi$ events collected with the BESIII detector. In this region of phase space the $K^0_S K^0_S$ system is dominantly produced through the $f_0(980)$. By performing a partial wave analysis, we determine the spinparity of the $X(1835)$ to be $J^{PC}=0^{+}$. The mass and width of the observed $X(1835)$ are $1844\pm9(\text{stat})^{+16}_{25}(\text{syst})$~\MeV~and $192^{+20}_{17}(\text{stat})^{+62}_{43}(\text{syst})$~MeV, respectively, which are consistent with the results obtained by BESIII in the channel $J/\psi\rightarrow\gamma\pi^+\pi^\eta^{\prime}$.
Publication Stats
3k  Citations  
1,079.37  Total Impact Points  
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Institutions

20092015

Nanjing University
 Department of Physics
Nanching, Jiangsu Sheng, China 
Guangxi University
Yungning, Guangxi Zhuangzu Zizhiqu, China


19702014

Institute of physics china
Peping, Beijing, China


2013

Chinese Academy of Sciences
Peping, Beijing, China


19982013

Government of the People's Republic of China
Peping, Beijing, China 
Hangzhou University
Shanghai, Shanghai Shi, China


2011

Henan University of Science and Technology
Honanfu, Henan Sheng, China


2010

RuhrUniversität Bochum
Bochum, North RhineWestphalia, Germany


19842010

Nankai University
T’ienchingshih, Tianjin Shi, China


2008

University of Toronto
Toronto, Ontario, Canada


20072008

University of Jinan (Jinan, China)
Chinanshih, Shandong Sheng, China


2006

Uppsala University
Uppsala, Uppsala, Sweden


20002001

Shanghai Jiao Tong University
Shanghai, Shanghai Shi, China


1999

National Tsing Hua University
 Nuclear Science and Technology Development Center
Hsinchuhsien, Taiwan, Taiwan 
Peking University
 Department of Technical Physics
Peping, Beijing, China


1992

Boston University
Boston, Massachusetts, United States
