Measuring D0-D0 mixing in D→f0(980) K and more

We investigate the D⁰-D⁰ mixing through the doubly Cabibbo suppressed (DCS) channel D0→f₀(980)K^*0 and its charge conjugate channel, in which the K^*0 meson is reconstructed in both K⁺π^－ and K_Sπ⁰ final state. Although the decay D⁰→f₀(980)K^* has a small branching ratio, the final state mesons are relatively easy to identify. The f₀(980) meson can be replaced by the S-wave π⁺π^－ state, or a longitudinally polarized vector meson ρ⁰. All mixing parameters, including the mass difference and decay width difference, can be extracted by studying the time-dependent decay width of these channels. We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

Energy dependence of non-linear dynamical features in e+e－ collisions

A study of the dynamical fluctuation properties at various c.m. energies in e⁺e^－ collisions is performed using the Monte Carlo method. The results suggest that, after the normalized factorial moments of 3-dimensional phase space are analyzed using an isotropical phase space partition, the NFM describing non-linear dynamical properties show a power-law scaling, i.e., the dynamical fluctuations in higher dimensional phase space are isotropic. For c.m. energies √s≤80 GeV, the scaling exponents φ_q increase rapidly with the c.m. energy and for c.m. energies √s>80GeV, the φ_q gradually saturate.     

Developments in accelerator mass spectrometry (AMS) method for 182Hf

The present detection limit for ¹⁸²Hf at CIAE HI-13 AMS systems could not satisfy various applications (e. g. detection of a nearby supernovae signal). Therefore, techniques were developed in this work to improve the AMS measurement of ¹⁸²Hf mainly on building a new injector and using a method that based on solid-phase reaction for the preparation of HfF₄ samples from HfO₂. The experimental results show that mass resolution of the injector can reached 630, and the F^－/O－ and beam current of ¹⁸⁰HfF₅^－ for HfF₄ samples produced by dry method is about 2—3 times and 1.5 times of that by previously method, respectively.     

T2K indication of relatively large θ13 and a natural perturbation to the democratic neutrino mixing pattern

The T2K Collaboration has recently reported a remarkable indication of the ν→ν oscillation which is consistent with a relatively large value of θ₁₃ in the three-flavor neutrino mixing scheme. We show that it is possible to account for such a result of θ₁₃ by introducing a natural perturbation to the democratic neutrino mixing pattern, without or with CP violation. A testable correlation between θ₁₃ and θ₂₃ is predicted in this ansatz. We also discuss the Wolfenstein-like parametrization of neutrino mixing, and comment on other possibilities of generating sufficiently large θ₁₃ at the electroweak scale.     

O(α_sv~2) correction to J/ψ plus η_c production in e~+e~- annihilation at s~(1/2)=10.6 GeV

Based on the nonrelativistic QCD factorization approach, O(αsv2) corrections to J/ψ plus ηc production in e+e-annihilation at √ s=10.6 GeV are calculated in this work. The numerical results show that the correction at αsv2order is only about a few percent of the total theoretical result. This indicates that the perturbative expansions become convergent and that a higher order correction will be smaller. The uncertainties from the long-distance matrix elements, renormalization scale and the measurement in the experiment are also discussed. Our result is in agreement with the previous result by Jia.     

Structure of β-emitting nuclei 29P

The extoic structure of ²⁹P was investigated by measuring its magnetic moment in the ground state with β-NMR method. We got the experimental value of 1.2346 μ_N after diamagnetism correction. It is very close to the calculated value of 1.1009 μ_N computed with shell model. The shell model calculation also gave a proton density distribution of ²⁹P with a long tail. The present results show that 2s_1/2 proton in the ²⁹P may lead to the proton-skin structure.     

PAC investigation of qudropole interaction in nano-soft magnetic material Fe73.5Cu1Nb3Si13.5B9

The quadrupole interaction in nano-soft magnetic material Fe_73.5Cu₁Nb₃Si_13.5B₉ has been studied by perturbed angular correlation using ⁶²Zn probe nuclei from the ISOL radioactive nuclear beam facility at CIAE HI-13 tandem accelerator. Two quadrupole interaction frequencies ω₀₁=440 Mrad/s with a distribution width σ=0 and ω₀₂=90 Mrad/s with a width σ=0.48 are obtained. The fractions of ω₀₁ and ω₀₂ are 38% and 62%, respectively. The measured quadruple interaction parameters indicate that 62% of the implanted ⁶²Zn are located in the grain boundary and 32% in the grain.     

Description of the evolution of mixed-symmetry states in the N=78 isotonic chain with IBM2

The characteristics of the lowest mixed-symmetry states 2_ms⁺ and 1_ms⁺ for ¹³²Xe, ¹³⁴Ba and ¹³⁶Ce in the even-even N=78 isotones are investigated within the framework of the IBM2 model. The lowest mixed-symmetry state 2_ms⁺ levels for both a single isolated state in ¹³²Xe and ¹³⁶Ce and a fragmented state in ¹³⁴Ba are reproduced by the predictions. The agreement between the IBM2 calculation and the experimental values is good for the B(E2) and B(M1) transition probabilities both quantitatively and qualitatively. The predicted summed B(M1) strength follows the experimental data, remaining nearly constant as a function of proton number along the chain of the N=78 isotones.     

Is Ds(2700) a charmed tetraquark state?

In this article, we assume that the D_s(2700) is a tetraquark state, which consists of a scalar diquark and a vector antidiquark, and calculate its mass with the QCD sum rules. The numerical result indicates that the mass of the vector charmed tetraquark state is about M_V=(3.75±0.18) GeV or M_V=(3.71±0.15) GeV from different sum rules, which is about 1 GeV larger than the experimental data. Such tetraquark omponent should be very small in the D_s(2700).     

Comprehensive analysis of e+e-→γηc(2S)

We discuss the production of η_c(2S) through the process e⁺e^-→γη_c(2S), where the leading contribution originates from 1-loop electroweak corrections. Adopting some reasonable light-cone distribution amplitudes, we analyze the cross section of this process. As the electron-positron center of mass energy √s=3770 MeV, the typical production cross section of this process is about 1 fb.     

Dependence of the cross sections for Ir isotopes on the values of Qgg in the heavy ion collision

¹⁹⁷Au were irradiated with 47 MeV/u ¹²C ions. Iridium was produced via the multinucleon transfer reactions in bombardments of ¹⁹⁷Au with ¹²C. and was separated radiochemically from Au and the mixture of the reaction products. The γ radioactivities of Ir isotopes were measured by using a HPGe detector. The production cross sections of Ir isotopes were determined from activities of Ir isotopes at the end of bombardment and the other relative data. It has been found that the cross sections for neutron-rich isotopes of iridium show an exponential dependence on the values of Q_gg. Our experimental results also demonstrate lack of correlation between the cross sections and Q_gg in the case of neutron-deficient isotopes of iridium. The fact can be explained from that neutron-rich isotopes of iridium were produced in the deep inelastic transfer reactions.     

Recent progress in AMS measurement of 182Hf at the CIAE

In order to improve the accuracy of accelerator mass spectrometry (AMS) measurement for ¹⁸²Hf/¹⁸⁰Hf, a series of measurements have been taken in the AMS laboratory at the China Institute of Atomic Energy (CIAE). The major ones include the instantaneous monitoring of ¹⁸⁰HfF₅^- current, testing the stability of transmission, the alternate measurements of an unknown sample and standard, and the origin identification and minimization of background ¹⁸²W. The experimental details and the improvement in the measurement accuracy, as well as some useful suggestions for better satisfying the requirements of certain practical applications, are presented in this paper.     

Structure of A=11 double-Λ hypernuclei studied withthree-body forces

The energy levels and ΛΛ bond energy of the double-Λ hypernucleus ¹¹Be are calculated considering two- and three-nucleon forces. The interactions between the constituent particles are contact interactions that reproduce the low-energy binding energy of the nuclei. Effective action is constructed to involve the three-body forces. In this paper, we compare the binding energy result that is obtained with the experimental and other modern nucleon-nucleon potentials. The results of all the schemes agree very well, showing the high accuracy of our present ability to calculate the many-nucleon bound state with three-body forces. The experimental value of B_{Λ Λ}(_ΛΛ¹¹Be)=20.83 MeV seems to be more compatible with our calculated value of B_ΛΛ(_ΛΛ¹¹Be)=19.31 MeV in comparison with the calculated result of 18.23 MeV by Hiyama et al.     

Study of the structure of borromean nucleus 17Ne

The ¹⁷Ne nucleus is a possible candidate with a two-proton borromean halo structure. Since the theoretical model is difficult to handle the three-body system, it is difficult to determine the two-proton halo structure in ¹⁷Ne. In the present research, we try to study the breakup reaction of ¹⁷Ne. For the Borromean nuclei, one-proton knockout results in an unstable nucleus which is decaying further by proton emission. This process will result in an angular correlation between the direction of the aligned recoiling unstable nucleus and its decay products. The angular correlations can give us information about the configuration of the valence proton in the ¹⁷Ne. Furthermore, theoretical calculations indicate that the momentum distributions of ¹⁶F c.m are sensitive to the structure of the halo in ¹⁷Ne. Thus the measurement of momentum distributions of ¹⁶F c.m may also give us conclusive information on the structure of ¹⁷Ne. The present experiment has been done at IMP in Lanzhou using the radioactive beam ¹⁷Ne at 30.8 MeV/u on a 43mg/cm^{2 12}C target. The data analysis is under procedure and the primary results are provided.     

Off-Shell Effect of Quarks in Bs→γe+e-

We evaluate the rare decays B_s→γe⁺e^- in the standard model, considering the off-shell effect of quarks in B_s meson as well as some contributions neglected in previous works. It is found that the quarks off-shell are large. With the predicted branching ratios at order of 10^-8, it is expected that the radiative dileptonic decays will be detected in the LHC-b experiments.     

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

We present a search for new charmonium like states in e⁺e^－ annihilation using the initial-state radiation and the process e⁺e^－J/ψD^(*)D^(*). The analyses are based on a huge data sample recorded near the Υ(4s) resonance with the Belle detector at the KEKB e⁺e^－ asymmetric-energy collider.     

Cs2 Te photocathode fabrication system at Peking University

A cesium telluride (Cs₂Te) photocathode with a quantum efficiency of 13% at 253.7 nm (radiant incidence 200 μ/cm²) is fabricated by tellurium and cesium vapor deposition onto a stainless-steel substrate. The cesium telluride cathode will be used to provide a high-brightness electron beam source for the 3+1/2 photo-injector at Peking University. The design of the system, the fabrication procedures and the preliminary experimental results are presented in this paper.     

Strange magnetic moments of octet baryons under SU (3) breaking

Magnetic moments of octet baryons are parameterized to all orders of the flavor SU(3) breaking with the irreducible tensor technique in order to extract the contribution of each flavor quark to the magnetic moments of the octet baryons. The not-yet measured magnetic moment of ∑⁰ is predicted to be 0.649μ_N. Our parameterized forms for the magnetic moments are explicitly flavor-dependent, and hence each flavor component of the magnetic moments can be evaluated directly via the flavor projection operator. It is found that the strange magnetic moment of the nucleon is suppressed due to the small isoscalar anomalous magnetic moment of the nucleon. In particular, the strange magnetic form factor of the nucleon turns out to be positive, G_N^s(0)=0.428μ_N, which is consistent with recent data.