ξ(2230) Is Likely to Be a Glueball

On the basis of the recent results of ξ(2230) → π⁺π^-, pp and ξ(2230) → K⁺K^-, K_sK_s, measured by the BES Collaboration in J/ψ radiative decays, combined with the PSI85 experiment of pp → ξ(2230) → KK we argue that because of its very narrow partial decay widths to nn and KK (less than 1 MeV), its large production rate in J/ψ radiative decays (BR(J/ψ → γξ> 2.3×10^-3), and its flavor-symmetric couplings to ππ and KK, the ξ(2230) is very likely to to be a J^PC= (even)⁺⁺ glueball.     

Study on the Effects of the Light CP-odd Higgs via the Leptonic Decays of Pseudoscalar Mesons

To explain the anomalously large decay rate of Σ⁺→p+μ⁺μ^-, it was proposed that a new mechanism where a light CP-odd pseudoscalar boson of m_A1⁰=214.3 MeV makes a crucial contribution. Later, some authors have studied the transition π⁰→ e⁺e^- and r → γA₁⁰ in terms of the same mechanism and their result indicates that with the suggested mass one cannot fit the data. This discrepancy might be caused by experimental error of Σ⁺→ p+μ⁺μ^- because there were only a few events. Whether the mechanism is a reasonable one motivates us to investigate the transitions π⁰→ e⁺e^-;η(η')→ μ⁺μ^-; η_c→ μ⁺μ^-; η_b→τ⁺τ^- within the same framework. It is noted that for π⁰→ e⁺e^-, the standard model (SM) prediction is smaller than the data, whereas the experimental central value of η→μ⁺μ^- is also above the SM prediction. It means that there should be extra contributions from other mechanisms and the contribution of A₁⁰ may be a possible one. Theoretically calculating the branching ratios of the concerned modes, we would check if we can obtain a universal mass for A₁⁰ which reconcile the theoretical predictions and data for all the modes. Unfortunately, we find that it is impossible to have such a mass with the same coupling |gl|. Therefore we conclude that the phenomenology does not favor such a light A₁⁰, even though a small window is still open.     

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 Z_c(3900) and Z_c(4020) states, the X(3872) in e⁺e⁻ annihilation, and charmonium ψ(1³D₂) state, as well as measurements of the cross-sections of ωχ_cJ and ηJ/ψ, and the search for e⁺e⁻→ γχ_cJ and γY (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.     

SUSY Virtual Effects on the Production of tq at LEPPI

Virtual effects of supersymmetry on the-flavor changing process at LEPII are calculated in the minimal supersymmetric standard model (MSSM). We analyze the cross section of e⁺e^- → γ, Z⁰ → tq, and find that even for the most distinguishable mode e⁺e^- → γ, Z⁰ → tc, the effect is small compared with the SM expectation.     

BH~+离子基态及激发态的势能曲线和跃迁性质的研究

利用高精度的多组态相互作用及Davidson修正方法 (MRCI+Q),采用ACV5Z-DK全电子基组计算了BH~+离子的前4个离解通道B~+(~1S_g)+H(~2S_g),B~+(~3Pu)+H(~2S_g),B(~2P_u)+H~+(~1Sg)和B~+(~1Pu)+H(~2Sg)的9个Λ—S态的势能曲线.X~2Σ~+,A~2Π和B~2Σ~+态的光谱常数和已有实验值符合得很好,其中b~4Σ~+,3~2Σ~+,3~2Π和4~2Σ~+态的光谱常数为首次报道,3~2Π和4~2Σ~+态具有双势阱结构.预测了A~2Π和B~2Σ~+态的辐射寿命:τ(A~2Π)=239.2 ns和τ(B~2Σ~+)=431.2 ns.最后在考虑自旋轨道耦合效应下讨论了B~2Σ~+与A~2Π态的势能曲线的相交对激光冷却BH~+离子的影响.     

Perfect Single Qubit Mirroring Effects on Two and Three Maximally Entangled Qubits

Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state |iof the chain is swapped into the state |N-i within a time evolution interval τ.Such a phenomenon is an interesting way of transfering entanglement.An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past.We exploit such an expressions for calculating the evolution times in chains of both two and three spins.In the case of a chain of two qubits,we derive conditions under which the associated four Bell states diagonalize the Hamiltonian.It is found that for the two Bell states |Φ+and|Φ-,perfect mirroring does not occur(i.e.entanglement is not preserved under swapping).On the other hand,perfect single qubit mirror effect(entanglement preservation) indeed occurs for the other two Bell states |Ψ+and|Ψ- which are mapped into |Φ+and|Φ-respectively.For the case of a chain of three qubits,the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψ1,ψ2,χ1,and χ2 are studied.Due to the fact that quantum mirroring preserves maximal entanglement,the states ψ1 and ψ2 are not altered.However,quantum mirroring changes the states χ1 and χ2 only if we apply perfect quantum state mirroring in the site a=1 of the three qubits spin chain.The above constrains the preservation of maximal entanglement under qubit mirroring of such a state.Due to the fact that swapping has already been experimentally tested,a posible experimental implementations of single qubit mirroring is possible.     

Composite scalars in ee collisions and radiative Z decays

Starting point is the hypothesis that the observed Z→e⁺e⁻γ decays are mediated by a (composite) spin 0 boson X with 40m_X50 GeV. The consequences for e⁺e⁻→e⁺e⁻, e⁺e⁻→γγ and e⁺e⁻→ hadrons at PETRA are explored. PETRA experiments turn out to be sensitive up to masses m_X50 GeV; the best indicator for m_X 48 GeV is the angular distribution of Bhabha scattering.     

Chiral Extension of Standard Model and Rc,Rb Problems

The deviations of R_c, R_b fiom the standard model are discussed within our theory, the cbiral extension of standard model and its supersymmetrization. Combining R_c, R_b with the coupling constants gv, gA of Z⁰ decay, Γ(W⁺ → e⁺υ_e) of W⁺ and the Michel parameters p_γ of γ decay, the mixing angles between hadronic and leptonic quarks and the form factors of the leptonic axial currents are determined within experimental errors, from which it is found that the mass of down leptonic quark of the third generation is about twice the mass of top quark.     

Associated Productions of HZZ and HHZ at Linear Colliders in Large Extra Dimension Model

In this paper we investigate the effects of the large extra dimensions on the two processes e⁺e^-→ H⁰Z⁰Z⁰ and e⁺e^-→ H⁰Z⁰Z⁰ at linear colliders in both unpolarized and polarized collision modes. We find that the virtual Kaluza-Klein graviton exchange can significantly enhance the cross section from their standard model expectations for these two processes. The results show that the LED effect on the process e⁺e^-→ H⁰Z⁰Z⁰ allows the observation limits on the effective scale M_S to be probed up to 9.75 TeV and 10.1 TeV in the unpolarized and +-(λ_e⁺=1/2, λ_e^-=-1/2) polarized beam collision modes (with P_e⁺=0.6, P_e^-=0.8), respectively. For the process e⁺e^-→ H⁰Z⁰Z⁰, these limits on M_S can be probed up to 6.06 TeV and 6.38 TeV in the unpolarized and polarized collision modes separately. We find that the λ_e⁺=1/2, λ_e^-=-1/2 polarization collision mode in both process e⁺e^-→ H⁰Z⁰Z⁰ and e⁺e^-→ H⁰Z⁰Z⁰ may provide a possibility to improve the sensitivity in probing the LED effects.     

Energy Spectrum and Its Pressure-Induced Shift and g Factor of ZnS:Mn2+

By using strong-field scheme, the complete d⁵ energy matrix with D_2d symmetry has been constructed. Then, by diagonalization of this matrix at normal and various pressures,the whole energy spectrum [including the ground-state zero-field-splitting (GSZFS)], its PS and the g factor of the ground state for zns:Mn²⁺ have uniformly been calculated. According to the eigenfunctions and PS, the new assignments of five absorption bands have been given.The variation of tetragonal field with pressure makes a main contribution to the pressureinduced shift (PS) of GSZFS of zns:Mn²⁺, which supports the existence of tetragonal Jahn-Teller distortion in zns:Mn²⁺. It is found that when P≥62 kbar, t₂⁴(³T₁)e⁴T₁ merges with t₂e^{4 2}T₂, which has to be taken into account in the calculation of PS of the fifth band in the range of 1 bar ~ 95 kbar. It is demonstrated that the Mn²⁺ ions in ZnS:Mn²⁺ have tetrahedral coordination, and the difference between ζ and ζ' caused by the covalency effect is very important for GSZFS. The physical essentials of typical levels, GSZFS and their PS have been revealed. By taking into account the influence of covalency on t₂³(⁴A₂)e²(³A₂)⁴A₁ and t₂³(²E)e²(³A₂)⁴E, the positon of the third absorption band at normal pressure has been estimated.     

Four-Particle Entangled State Representation and Its Squeezing Transformation

The four-particle EPR entangled state | p,χ₂,χ₃,χ₄〉is constructed. The corresponding quantum mechanical operator with respect to the classical transformation p→e^λ₁p, χ₂→ e^λ₂χ₂, χ₃→e^λ₃χ₃, and χ₄→e^λ₄χ₄ in the state |p,χ₂ ,χ₃ ,χ₄〉is investigated, and the four-mode realization of the SU(1,1) Lie algebra as well as the corresponding squeezing operators are presented.     

The Three-Pion Decays of the a1(1260)

We investigate the decay of a₁⁺ (1260)→π⁺π⁺π^- with the assumption that the a₁(1260) is dynamically generated from the coupled channel ρπ and KK^* interactions. In addition to the tree level diagrams that proceed via a₁⁺ (1260)→ρ⁰π⁺→π⁺π⁺π^-, we take into account also the final state interactions of ππ→ππ and KK→ππ. We calculate the invariant π⁺π^- mass distribution and also the total decay width of a₁⁺ (1260)→π⁺π⁺π^- as a function of the mass of a₁(1260). The calculated total decay width of a₁(1260) is significantly different from other model calculations and tied to the dynamical nature of the a₁(1260) resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the ρπ component in the a₁(1260) wave function.     

Effects of Final-State Interactions on Inclusive Spin-Half Baryon Production from Time-Like Photon Fragmentation

In contrast to the hadronic tensor in the deeply inelastic scattering, we find that owing to the final-state interactions, time reversal invariance cannot make any constraint to the general expression of the photon fragmentation tensor for inclusive spin-half bafyon production. Correspondingly, there exists a novel fragmentation structure function F(z, Q²) that has no correspondence to any hadronic structure functions in the hadronic tensor of the deeply inelastic electron scattering off the spin-half baryon. Phenomenologically, F(z, Q²) determines the transverse polarization of the inclusively detected baryon in unpolarized electron-positron annihilation. In relation to the large transverse A polarization puzzle in fixed-target experiments, we suggest measuring the Λ polarization in e^- + e⁺ → Λ + X .     

Study on υμ, υγ, Decays and CP Non-Invariance at Early Epoch of the Universe

We study the υ_μ and υ_γ decays in the early epoch of the universe. If m_υγ > 2m_e, there would be a CP asymmetry between υ_γ→e⁺+e^-+υ_e and υ_γ→e⁺+ e^-+ υ_e. The resultant CP non-invariance is a function of temperature and density and can reach l0^-7 for a reasonable temperature range, but it is noticed that if m_υγ > 2υ_μ～200 MeV, the CP non-invariance can be much larger.     

Pair Production of the Doubly Charged Leptons Associated with a Gauge Boson γ or Z in e~+e~-and γγ Collisions at Future Linear Colliders

In this paper,we investigate the production of a pair of doubly charged leptons associated with a gauge boson V(γ or Z) at future linear colliders via e~+e~-and γγ collisions.The numerical results show that the possible signals of the doubly charged leptons may be detected via the processes e~+e~→VX~(++)X~(--)and γγ→VX~(++)X~(--)at future ILC or CLIC experiments.     

Pressure-Dependent Base-Wavefunction Admixture and Lifetime of R1 State of La3Lu2Ga3O12:Cr3+

As a key factor leading to the pressure-dependent R₁-line-shift reversal and R₁-state lifetime, at 10 K, the pressure-dependent variation of mixing-degree of |t₂²(³T₁)e⁴T₂〉 and |t₂³² E〉base-wavefunctions in the wavefunction of R₁ state of LLGG:Cr³⁺ has been calculated and analyzed. From this, the physical origin of the pressure-dependent R₁-line-shift reversal has been revealed. Furthermore, by using the pressure-dependent values of the sum of all square mixing-coefficients of |t₂²(³T₁)e⁴T₂〉in the wavefunction of R₁ state, the lifetimes of R₁ state of LLGG:Cr³⁺ at various pressures have been calculated, which are in good agreement with observed results. The quantum anticrossing effect between t₂³²E and t₂²(³T₁)e⁴T₂ levels due to both spin-orbital interaction and electron-phonon interaction is remarkable, which is related to the admixture of |t₂²(³T₁)e⁴T₂〉and |t₂³² E〉as well as the low-high crystal-field transition.     

Energy Spectrum,g Factors,Strain-Induced Level-Splittingsand R-Line Thermal Shift of MgO:V2+

Traditional ligand-field theory has to be improved by taking into account both pure electronic contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, the R line, t₂^{3 2}T₁ and t₂^{3 2}T₂ lines, t₂² (³T₁)e⁴T₂, t₂² (³T₁)e⁴T₁ and t₂ e²(⁴A₂)⁴T₁ bands, g factors of t₂^{3 4}A₂ and t₂^{3 2}E, four strain-induced level-splittings and R-line thermal shift of MgO:V₂₊ have been calculated. The results are in very good agreement with the experimental data. It is found that for MgO:V₂₊, the contributions due to electron-phonon interaction (EPI) come from the first-order term; the contributions from the second-order and higher terms are insignificant. In thermal shift of R line of MgO:V₂₊, the temperature-dependent contribution due to EPI is dominant. The results obtained in this work may be used in theoretical calculations of other effects of EPI.     

Energy and rotation-dependent stereodynamics of H(~2S) + NH(a~1?) → H_2(X~1Σ_g~+) + N(~2D) reaction

Quasi-classical trajectory calculations are performed to study the stereodynamics of the H(~2S) + NH(a~1?) →H_2(X~1Σ_g~+) + N(~2D) reaction based on the first excited state NH_2(1~2A') potential energy surface reported by Li et al.[Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k–k' distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k–k' distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j' of the product H_2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment.     

YAG中Cr3+和Yb3+的发光特征以及Cr3+和Yb3+之间的能量传递过程

室温下观察了YAG:Cr³⁺,Yb³⁺材料在近红外区域的发光特性, 并通过对Cr³⁺:⁴T₂和Yb³⁺:²F_5/2能级辐射跃迁寿命以及它们布居时间的比较研究,提出了从Cr³⁺到Yb³⁺的能量传递机制,同时借助于能级图描述了从Cr³⁺到Yb³⁺的能量传递以及Cr³⁺和Yb³⁺的近红外发光过程。