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.     

A new two-mode thermo- and squeezing-mixed optical field

We propose a new two-mode thermo-and squeezing-mixed optical field, described by the new density operator ρ=1-e~f-|g|~2 e~(ga~+b~+)e~(fa~+a)|0〉 f_(bb) 〈0| e~(g*ab), where |0〉_(bb) 〈0| is the b-mode vacuum, e ~(fa~+a)represents the thermo-field, and e~(ga~+b~+) indicates squeezing. The photon statistics for ρ is studied by virtue of the method of integration within ordered product(IWOP) of operators. Such a field can be generated when a two-mode squeezed state passes through a one-mode dissipation channel.     

Deformation of Superoperator's Kraus Representation Derived by Weyl Correspondence and Entangled State Representation

By virtue of the Weyl correspondence and based on the the technique of integration within an ordered product of operators, we show under what condition the superoperator's Kraus representation ρ^ˊ=∑_μ A_μρA_μ^† can be deformed as ρ^ˊ=(1/π)∫d²αB(α)D(α)ρD^†(α), where D(α) is the displacement operator, B(α) is a probability density related to the classical Weyl correspondence of A_μ. An alternate discussion by using the entangled state representation and through a quantum teleportation process is also presented.     

Improved Ligand-Field Theoretical Calculation of R-Line Pressure-Induced Shift of MgO:V2+

By means of an improved ligand-field theory, the “pure electronic” PS and the PS due to EPI of R line of MgO:V²⁺ have been calculated, respectively. The calculated results are in very good agreement with the experimental data. The behaviors of the pure electronic PS of R line of MgO:V²⁺ and the PS of its R line due to EPI are different. It is the combined effect of them that gives rise to the total PS of R line, which has satisfactorily explained the experimental results. The mixing-degree of |t₂²(³T₁)e⁴T₂〉and |t₂^{3 2}E〉 in the wavefunction of R level and its variation with pressure have been calculated and analyzed. The comparison between the feature of R-line PS of MgO:V²⁺ and that of MgO:Cr³⁺ has been made.     

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.     

On Diagonal P-Representation of Superposition Field of Two Light Modes

For the superposition field a₁^†+a₂^† of two light modes we introduce an appropriate diagonal P-representation which is constructed on the common eigenvectors |z,x〉of (X₁-X₂) and a₁+a₂, where X_i=(a_i+ a_i^†)/√(2), [a_i,a_i^†] =δ_ij. It is remarkable that |z,x〉make up a new quantum mechanical representation.     

The ΔNγ electromagnetic transition form factors GM(q) and GE(q)

A parameter-free, nonperturbative calculation of the ΔNγ electromagnetic transition amplitudes GM*(q2), GE*(q2), and the resonant multipole ratio REM(q2)≡E1+3/2(q2)/M1+3/2(q2) is performed in terms of the well-known nucleon isovector Sachs form factor GMV. Our methods are fully relativistic with conservation of the electromagnetic current guaranteed. We find that GM*(q2) decreases more rapidly than the nucleon dipole form factor when −q21 GeV2/c2 and that REM(q2) remains small even for very high four-momentum transfer implying that the perturbative QCD prediction REM(q2)→1 is purely asymptotic and is valid only for extremely high |q2|.     

Absorption spectra and isotope shifts of the(2, 0),(3, 1), and(8, 5) bands of the A~2Π_u-X~2Σ_g~+ system of ~(15)N_2~+ in near infrared

The high-resolution absorption spectra of the(2, 0),(3, 1), and(8, 5) bands of the A~2Π_u–X~2Σ_g~+system of~(15) N_2~+ have been recorded by using velocity modulation spectroscopy technique in the near infrared region. The rotational constants of the X~2Σ_g~+and A~2Π_u states of~(15) N_2~+ were derived from the spectroscopic data. The isotope shifts of these bands of the A~2Π_u–X~2Σ_g~+system of~(14) N_2~+ and~(15) N_2~+ were also analyzed and discussed.     

关于93Mo中21/2+晕阱的来源(英文)

本研究通过壳模型计算研究了N=51的同中子素91Zr、93Mo和95Ru中高自旋晕态21/2+的同核异能态现象。计算发现,低角动量的p_1/2轨道上的质子是仅在93Mo中存在21/2+晕阱的主要原因。同时,本工作还研究了N=52的同中子素92Zr、94Mo和96Ru中10₁+-12₁+能级结构的系统性,发现94Mo中的10₁+-12₁+能级间隙相对最小,考虑到与93Mo的17/2₁+-21/2₁+能级相似的组态,这一结果为93Mo中出现21/2+晕阱提供了补充性的论证。Isomerism of the high-spin yrast 21/2+ states of the N=51 isotones 91Zr, 93Mo and 95Ru has been investigated using the shell model calculations. It is found that the low-j πp_1/2 is responsible for the only yrast trap in 93Mo. In addition, the relatively smaller 10₁+-12₁+ level spacing in 94Mo has been found by investigating the systematics of the 10₁+-12₁+ level structures in the N=52 isotones 92Zr, 94Mo and 96Ru. This result provides a supplementary argument to the origin of the 21/2+ yrast trap in 93Mo from the viewpoint of the similarity between the configurations of 10₁+-12₁+ states in 94Mo and those of 17/2₁+-21/2₁+ states in 93Mo.     

Energy Spectrum of La3Lu2Ga3O12：Cr^3＋ and Its Pressure-Induced R-Line-Shift Reversal

By means of both the theory for pressure-induced Shifts （PS） of energy spectra and the theory for shifts of energy spectra due to electron-phonon interaction （EPI）, the normal-pressure energy spectra of α and β centers of Cr^3＋ ions for LLGG：Cr^3＋ and the PS＇s of R1 lines and U band of these centers have been calculated at 10 K, respectively. The total calculated results are in very good agreement with the experimental data. For LLGG：Cr^3＋, the pressureinduced low-high crystal-field transition and the reversal of R1-line PS take place. The pressure-dependent variation of Rmix^ei （2E - 4T2） [mixing-degree of （t2^2 （^3T1）e^4T2） and （t2^3 E） base-wavefunctions in the wavefunction of R1 state without EPI] plays a key role for the reversal of R1-line PS. The behavior of the pure electronic PS of R1 line is quite different from that of the PS of R1 line due to EPI. It is the combined effect of them that gives rise to the total PS of R1 line. The comparison between R1-line PS＇s of GSGG：Cr^3＋ and LLGG：Cr^3＋ has been made. It is found that a peak of R1-line PS appears at Rmix^ei （^2E - ^4T2） ≈ 0.08.     

关于动态位错场张量势的规范变换

本文引入并论证了描述动态位错场的张量势(A与B)的规范交换问题,而且证明这种变换可采取这样的形式:B′=B+▽F, A′=A-ρ?/(?t)▽G,x′=x-ρ?/(?t)F,其中x_i=e_iklA_kl。至于F与G,则为带有很大任意性的时空坐标的矢量函数,但它们要满足以下关系式:F=▽×G,▽²F-1/G_t²-(?²/?t²)F=0.进 关键词：     

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.     

Nonlinear Response of Granular Composite Mediurn

In this paper, the linear and nonlinear responses of granular composite medium consisting of spherical grains with coating shells embedded in a host medium are studied. We assume that the shell and the host medium are linear (the dielectric constants of which are ε⁰ and ε_m⁰ respectively), while the spherical grain is nonlinear (the diektric constant of which is ε_c = ε_c⁰ + χ_c|E_c|^β). Starting from the definition (D) = ε_eff and taking in to account the corrections to the local field within the spherical grains, expressions for the linear and high-order nonlinear susceptibilities are presented.     

Gd3+,Yb3+和Tm3+共掺杂氟化物纳米晶中Yb3+-Tm3+-Gd3+间的能量传递

用水热法合成了Y_0.8-x-yF₃∶Gd_x³⁺,Yb_0.2³⁺,Tm_y³⁺纳米晶的上转换发光材料。在典型的Y_0.595F₃∶Gd_0.200³⁺,Yb_0.200³⁺, Tm_0.005³⁺纳米微晶中,在980 nm激光激发下,观察到了Tm³⁺的紫外、紫色上转换发射明显增强和来自于Gd³⁺的⁶D_9/2、⁶I_J、⁶P_5/2及⁶P_7/2能级到基态⁸S_7/2能级的紫外发射。通过比较Y_0.8-x-yF₃∶Gd_x³⁺ ,Yb_0.2³⁺,Tm_y³⁺纳米晶样品的上转换发光性质以及Tm³⁺和Gd³⁺中一些激发态的能级寿命,借助于能级图描述了Yb³⁺-Tm³⁺-Ga³⁺之间的有效的能量传递过程。     

Na_2~+离子较低电子态势能曲线和光谱常数的理论研究

通过多组态相互作用方法,结合原子有效芯势与极化势,利用非收缩的高斯基函数,计算了Na_2~+分子对应最低9个解离限的36个电子态的势能曲线.基于计算获得的束缚态势能曲线,拟合给出了相应的光谱常数,并与已有的实验和理论结果进行了比较.同时,给出了部分电子态的振动-转动能级和一些同类态避免交叉点的信息.计算获得的光谱信息对冷原子分子光谱与动力学的研究具有参考价值.     

Reanalysis of the Z_c(4020), Z_c(4025), Z(4050) and Z(4250) as Tetraquark States with QCD Sum Rules

In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the C γμ- Cγνtype scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula μ = (M 2X/ Y /Z-(2Mc)2)~(1/2) to determine the energy scales of the QCD spectral densities. The predictions MJ =2=(4.02+0.09-0.09) GeV, MJ =1=(4.02+0.07-0.08) GeV favor assigning the Zc(4020) and Zc(4025) as the JP C= 1+-or 2++diquark-antidiquark type tetraquark states, while the prediction M++J =0=(3.85+0.15-0.09) GeV disfavors assigning the Z(4050) and Z(4250) as the JP C= 0diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0++, 1+-, 2++diquark-antidiquark type tetraquark states in details.     

The Multi-Pole Neveu-Schwarz Algebra on Riemann Supersphere

According to the Riemann-Roch theorem, we construct bases H_-n⁽ⁱ⁾ and N_-m^(f), for the meromorphic λ = -1 and λ = -1/2 differentials on the Riemann sphere S². The dual bases, A_-n⁽ⁱ⁾, and D_-m^(j), of these meromorphic λ differentials on C_r curves are defined. Expanding the component fields TB(z) and TF(z) of the stress-energy tensor T(z) in the superconformal field theory by the dual bases A_-n⁽ⁱ⁾, and D_-m^(j), respectively, we obtain a series of expanding coefficients. The commutation relations among these coefficients are given explicitly, which,is just the multi-pole Neveu-Schwarz algebra with central extensions on the Riemann supersphere S. Physical implics tions of the algebra are also discussed.     

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.     

Energy Spectra of the Tunable Laser Crystal Gd3Ga5O12:Cr3+ and Their Pressure-Induced Shifts

By means of both the theory for pressure-induced shifts (PS) of energy spectra and the theory for shifts of energy spectra due to electron-phonon interaction (EPI), at 300 K, the `pure electronic' contributions and the contributions from EPI to R₁ line, R₂ line, and U band of GGG:Cr³⁺ as well as their PS have been calculated, respectively. The total calculated results are in good agreement with all the experimental data. Their physical origins have been explained. It is found that the mixing-degree of |t₂²(³T₁)e ⁴T₂> and |t₂³²E> base-wavefunctions in the wavefunctions of R₁ level of GGG:Cr³⁺ is considerable under normal pressure, and the mixing-degree rapidly decreases with increasing pressure. The change of the mixing-degree with pressure plays a key role for PS of R₁ line or R₂ line. At 300 K, both the temperature-independent contribution to R₁ line (or R₂ line or U band) from EPI and the temperature-dependent one are important. The remarkable difference between pressure-dependent behaviors of PS of R₁ lines of GGG:Cr³⁺ and GSGG:Cr³⁺ results from the differences of their microscopic properties. The features of emission spectra of GGG:Cr³⁺ at various pressures have satisfactorily been explained.