On the Mixed Propagator Approach to ρ-ω Mixing

The mixed propagator (MP) approach to ρ-ω mixing is discussed. It is found that under the pole-approximation assumption the results of MP approach is not compatible both with the effective Lagrangian theory andwith the experiment measurement criterion. To overcome these inconsistent, we propose a new MP approach in whichthe physical states of ρ and ω are determined by the requirement of experimental measurement to meson resonance. Interms of this new MP approach, the EM pion form factor Fπ and form factors of ρo →π0γ and of ω→πo γ are derived.The results of Fπ are in good agreement with data. The form factor of ρo →π0γ exhibits a hidden charge-asymmetryenhancement effect which agrees with the prediction of the effective Lagrangian theory.     

On the Mixed Propagator Approach to ρ-ω Mixing

The mixed propagator (MP) approach to ρ-ω mixing is discussed. It is found that under the pole-approximation assumption the results of MP approach is not compatible both with the effective Lagrangian theory and with the experiment measurement criterion. To overcome these inconsistent, we propose a new MP approach in which the physical states of ρ and ω are determined by the requirement of experimental measurement to meson resonance. In terms of this new MP approach, the EM pion form factor F_π and form factors of ρ⁰→π⁰γ and of ω→π⁰γ are derived. The results of F_π are in good agreement with data. The form factor of ρ⁰→π⁰γ exhibits a hidden charge-asymmetry enhancement effect which agrees with the prediction of the effective Lagrangian theory.     

Equation of State of Nuclear Matter in Chiral σ-ω Model

The equation of state of nuclear matter is studied in the 1-loop approximation of chiral linear σ-ω model. By introducing the density-dependent coupling constants, the problem of tachyon pole in the chiral σ-ω model is resolved. The 1-loop contributions of σ and π mesons to the nucleon's binding energy are included, while the empirical properties of nuclear matter such as saturation density, binding energy, and incompressibility are well reproduced.     

Mixing and decays of ρ- and ω-mesons

Isospin-violating mixing of ρ- and ω-mesons is reconsidered in terms of propagators. Its influence on various pairs of (ρ,ω)-decays to the same final states is demonstrated. Some of them, (ρ,ω)↦π⁺π^- and (ρ,ω)↦πγ, have been earlier discussed in the literature, others (e.g., (ρ,ω)↦ηγ and (ρ,ω)↦e ⁺ e ^-) are new in this context. Changes in partial widths for all the decay pairs are shown to be correlated. The set of present experimental data, though yet inconclusive, provides some limits for the direct (ρω)-coupling and indirectly supports enhancement of ρ↦πγ in comparison with ρ^±↦π^±γ, though not so large as in some previous estimates. Received: 16 September 2002 / Accepted: 23 September 2002 / Published online: 4 February 2003 RID="a" ID="a"e-mail: azimov@pa1400.spb.edu Communicated by V.V. Anisovich     

Masses and Sigma Terms of Pentaquarks in Chiral Perturbation Theory

Assuming that the recently θ＋ and other exotic resonances belong to the pentaquark i0 of SU（3）I with J^P = 1/2, we constructed a relativistic effective lagrangian in the frame work of baryon chiral perturbation theory. The masses of pentaquarks under isospin symmetry is determined by calculating the propagator to one loop, where the extended on-mass-shell renormalization scheme is applied. Using the experimental data for masses of θ＋, Ξ and N, we estimated the mass of Σ and the a terms.     

Resummation Study on Decay ρ→ππ in U(2)L×U(2)R Chiral Theory of Mesons

We improve O(p⁴) calculation in U(2)_L×U(2)_R chiral theory of mesons by resummation calculation for vector mesons physics and restudy decay ρ→ππ. We obtain a complete and compact expression for f_ρππ(p²) (up to O(p^∞)), from which an important non-perturbative conclusion is drawn from convergence and unitarity consideration.     

A Study of Electromagnetic Transition of △(1232) Resonance

Point form relativistic dynamics of relativistic quantum mechanics is employed to estimate the photon and electroproduction amplitudes of △(1232) resonance. Results are compared with the non-relativistic work, and the differences between the two frame works are discussed.     

A Study of Electromagnetic Transition of △（1232） Resonance

Point form relativistic dynamics of relativistic quantum mechanics is employed to estimate the photon and electroproduction amplitudes of A(1232) resonance. Results are compared with the non-relativistic work, and the differences between the two frame works are discussed.     

The Chiral and Angular Momentum Content of the ρ-Meson

It is possible to define and calculate in a gauge-invariant manner the chiral as well as the partial wave content of the quark–antiquark Fock component of a meson in the infrared, where mass is generated. Using the variational method and a set of interpolators that span a complete chiral basis we extract in a lattice QCD Monte Carlo simulation with n _f = 2 dynamical light quarks the orbital angular momentum and spin content of the ρ-meson. We obtain in the infrared a simple ³ S ₁ component as a leading component of the ρ-meson with a small admixture of the ³ D ₁ partial wave, in agreement with the SU(6) flavor–spin symmetry.     

Study of various charged ρ-meson masses in asymmetric nuclear matter

We study the effective masses of p-mesons for different charged states in asymmetric nuclear matter （ANM） using the Quantum Hadrodynamics II model. The closed form analytical results are presented for the effective masses of p-mesons. We have shown that the different charged p-mesons have mass splitting similar to various charged pions. The effect of the Dirac sea is also examined, and it is found that this effect is very important and leads to a reduction of the different charged p-meson masses in ANM.     

Transport coefficients in Chiral Perturbation Theory

We present recent results on the calculation of transport coefficients for a pion gas at zero chemical potential in Chiral Perturbation Theory (ChPT) using the Linear Response Theory (LRT). More precisely, we show the behavior of DC conductivity and shear viscosity at low temperatures. To compute transport coefficients, the standard power counting of ChPT has to be modified. The effects derived from imposing unitarity are also analyzed. As physical applications in relativistic heavy-ion collisions, we show the relation of the DC conductivity to soft-photon production and phenomenological effects related to a non-zero shear viscosity. In addition, our values for the shear viscosity to entropy ratio satisfy the KSS bound.     

Tests of the final-state radiation model at DAFNE near <Emphasis Type="Italic">π</Emphasis><Superscript>+</Superscript><Emphasis Type="Italic">π</Emphasis><Superscript>-</Superscript> threshold

Effects due to the non-pointlike behaviour of pions in the process e ⁺ e ^-→π ⁺ π ^- γ can arise for hard photons in the final state. By means of a Monte Carlo event generator, which also includes the contribution of the direct decay φ→π ⁺ π ^- γ, we estimate these effects in the framework of the resonance perturbation theory. We consider angular cuts used in the KLOE analysis of the pion form factor at threshold. A method to reveal the effects of the non-pointlike behaviour of pions in a model-independent way is proposed.     

红外透过、反射吸收光谱研究手性液晶(M1)LB膜的结构与取向

利用ＦＴＩＲ光谱研究了一种手性液晶化合物（Ｍ１）ＬＢ膜的结构与取向,该化合物可以形成稳定的单层与多层膜。手性分子中,芳香环平面向于垂直基片表面,分子中的烷基链部分则与基底表面法线方向成一定的角度。     

Chiral dynamics of kaon-nucleon interactions,revisited

The ¯N system close to threshold is analyzed in view of the new accurate DEAR kaonic hydrogen data. The calculations are performed using chiral SU(3) effective field theory in combination with non-perturbative schemes based on coupled channels. Several variants of such approaches are compared with experimental data and the differences in the results are discussed. Coulomb and isospin-breaking effects turn out to be important and are both taken into account. The pole structure of the Λ(1405)-resonance close to the ¯N threshold is critically examined.     

The Fubini-Furlan-Rosetti sum rule and related aspects in light of covariant baryon chiral perturbation theory<Superscript>⋆</Superscript>

We analyze the Fubini-Furlan-Rosetti sum rule in the framework of covariant baryon chiral perturbation theory to leading one-loop accuracy and including next-to-leading-order polynomial contributions. We discuss the relation between the subtraction constants in the invariant amplitudes and certain low-energy constants employed in earlier chiral perturbation theory studies of threshold neutral pion photoproduction off nucleons. In particular, we consider the corrections to the sum rule due to the finite pion mass and show that below the threshold they agree well with determinations based on fixed-t dispersion relations. We also discuss the energy dependence of the electric dipole amplitude E₀₊.     

基于功能化的金纳米的共振瑞利散射方法手性识别肉碱对映体

一种不经分离而同时测定手性对映体的简便方案是非常有趣和有用的.提出一种基于共振瑞利散射(RRS)光谱技术手性识别新方法,利用功能化的金纳米粒子(Au NPs)同时检测肉碱对映体.Au NPs的RRS强度很弱,但当Cu2+存在时,RRS强度显著增加.更有趣的是,肉碱对映体均可以降低Cu2+-Au NPs体系的RRS强度,但D-肉碱使RRS降低更多.在最优实验条件下,均有良好的线性关系并有很好的相关系数以及较低的检出限.由此,这种方法可以计算出肉碱对映体的对映体比率和对映体分数.并应用于胶囊样品中肉碱对映体混合物手性识别的研究.该方法不需要复杂的手性修饰处理,并具有简捷低消耗、灵敏度高、选择性好等优点.     

电场作用下染料掺杂手性向列相液晶器件激光辐射谱研究

研究了电场作用下染料掺杂手性向列相液晶器件激光辐射谱。设计了两种电极结构,分别对正性和负性液晶器件施加横向和纵向电场,采用532 nm的Nd∶YAG脉冲固体激光器泵浦样品。对正性液晶器件施加电场,在 630～660 nm范围获得多波长的激光输出。对负性液晶激光器件施加电场,获得调谐范围为18.5 nm的激光输出。由器件织构和光子禁带的变化,进行了深入的分析。正性液晶器件,在电场力矩与扭曲力矩相互竞争过程中,引起液晶的流动,光子禁带上下浮动,因此不仅在禁带边沿,禁带内也出现激光辐射。而负性液晶器件随着电场强度增大,液晶螺距收缩,禁带蓝移,输出激光波长从681.0 nm蓝移到662.5 nm,出射激光波长为光子禁带边沿处。负性液晶器件在电场作用下的稳定性较好。     

Study of Color Transparency in Electroproduction of Vector Mesons Off Nuclei

Within a light-cone Quantum Chromodynamics formalism based on the Green function technique incorporating color transparency, coherence length effects and gluon shadowing we study electroproduction of vector mesons off nuclei. We found rather large color transparency effects in the range of Q ²(10-20) GeV². They are stronger at low than at high energies and can be easily identified by HERMES or at JLab. We provide predictions for incoherent and coherent vector meson production for future measurements.     

The ρ-π Puzzle of J/φ and φ′ Decays

The recent BES Collaboration data on φ →PV, particularly the isospin violating mode φ′ → π^oω^o and finding of a finite number for B(φ′ → K^*OK^O), enable us now to deal more precisely about the challenges to theory concerning this extraordinary and remarkableso-called ρ-π puzzle of J/φ and φ′ decays. In terms of the existing data and deploying the simplest phenomenology, measurement of φ′ → π⁺π^- and whether a finite number for the K^*+K^- mode might require a significantly large accumulation of data remain interesting questions.