π介子凝聚对中子星物质的影响

在相对论平均场理论框架下研究了π-介子凝聚对包括Δ共振态的中子星物质状态方程及其粒子分布的影响.研究表明,π-介子凝聚的存在对中子星物质的粒子分布有明显影响,使Δ-粒子出现推迟,Δ+粒子出现提前.π-介子凝聚的出现还使中子星物质的状态方程变软.尽管这种改变很小,但这种变软的趋势仍具有重要的意义.

π~－－^（12）C非弹性散射与π介子放射疗法

该文研究了π介子放射疗法中的物理本质，用扭曲波冲量近似（ＤＷＩＡ）方法，具体计算了π￣－－￣（１２）Ｃ非弹性散射，最后给出了π介子治癌的几个主要特点。

Study on Charged Top-Pion Decay Processes

In the framework of top-color assisted technicolor (TC2) theory, we study the four decay processes of charged top-pion, i.e., . The decay branching ratio of these modes are calculated. The results show that the main decay channels of charged top-pion are the tree level modes: and . Light is easier to be detected than heavy one at future coliders. So, the study provides us with some useful informations to search for charged top-pion.

Some Properties of $\pi$ Meson in Nuclear Matter with Finite Density

In the GCM we study some properties of meson as the Goldstone bosons in a nuclear matter with finite density. Using the effective action in a nuclear matter, we calculate the decay constant and mass as functions of the chemical potential. The relation between the chemical potential and the density of a nuclear matter is firstly given here. We find that and monotonously decrease as nuclear matter density increases. The result is consistent with the usual assumption that the chiral symmetry is gradually restored as the density of a nuclear matter increases.

π介子治疗晚期癌症的生物——物理机理

目前,晚期癌症是不治之症,人们对这种病比较关注。医生对患者采取药物和手术治疗也采用放射性疗法。放射性治疗(如镭射线)对早期癌症有一定疗效,但对晚期癌症仍不能治愈。国外有资料报导,尝试用π^-介子射线治疗晚期癌症,已治愈多例。本文试从生物—物理角度论述其理论依据。

The Role of α1(1260) in π^-p→α1^-(1260)p and π^-p → π^-ρ^0p Reactions Near Threshold

We report on a theoretical study of the π^-→α1（1260）p and π^-→π^-~0p reactions near threshold within an effective Lagrangian approach.The production process is described by t-channel ρ^0 meson exchange.For the π^-→π^-ρ~0p reaction,the final π^-p^0 results from the decay of the α1（1260） resonance,which is assumed as a dynamically generated state from the K＊ K and ρπ coupled channel interactions.We calculate the total cross section of the π^-→α1（1260）p reaction.It is shown that,with the coupling constant of the α1（1260） to ρπ channel obtained from the chiral unitary theory and a cut off parameter Δρ～1.5 GeV in the form factors,the experimental measurement can be reproduced.Furthermore,the total and differential cross sections of π^p→α1（1260）p→π^ρ^0p reaction are evaluated,and it is expected that our model calculations can be tested by future experiments.These reactions are important for the study of the α1（1260） resonance and would provide further constraints on the properties of the α1（1260） state.

Is the existence of a J/ψJ/ψbound state plausible?

In a recent measurement LHCb reported pronounced structures in the J/ψJ/ψspectrum.One of the various possible explanations of those is that they emerge from non-perturbative interactions of vector charmonia.It is thus important to understand whether it is possible to form a bound state of two charmonia interacting through the exchange of gluons,which hadronise into two pions at the longest distance.In this paper,we demonstrate that,given our current understanding of hadron-hadron interactions,the exchange of correlated light mesons(pions and kaons)is able to provide sizeable attraction to the di-J/ψsystem,and it is possible for two J/ψmesons to form a bound state.As a side result we find from an analysis of the data for theψ/(2 S)J/ψππtransition including bothππand KK final state interactions an improved value for theψ(2 S)→J/ψtransition chromo-electric polarisability:|αψ(2 S)J/ψ|=(1.8±0.1)GeV-3,where the uncertainty also includes the one induced by the final state interactions.

Intermediate Energy Pion-^(20)Ne Elastic Scattering in the α+^(16)O Model of (20)~Ne

We present an analysis of π-^20Ne elastic scattering at intermediate energy basing on the α＋^16O model of the ^20Ne nucleus and in the framework of Glauber multiple scattering theory. Satisfactory agreement with the general features of the experimental data of pion elastic scattering on the neighboring 4N-type nuclei is obtained without any free parameters. Compared with the experimental angular distributions of pion elastic scattering on ^12 C, ^16O, ^24Mg, and ^28Si nuclei, the diffractive patterns and the positions of the dips and peaks in the angular distributions of ^π-^20Ne elastic scattering are reasonably predicted by the calculations.

Photoproduction of the Charged Top-Pions at the LHeC

The top triangle moose （TTM） model, which can be seen as the deconstructed version of the topcolor- assisted technicolor （TC2） model, predicts the existence of the charged top-pious πt± in low energy spectrum. In the context of this model, we consider photoproduction of πt± via the subprocesses γb→tπt- and γb -tπt＋ at the large hadron-electron eollider （LHeC）, in which high energy photon beams are generated by using the Compton backscatting method. We find that, as long as the charged top-pious are not too heavy, they can be abundantly produced via γb collision.