中介子

This thesis focuses on the spectral function of rho meson in hot and dense pion medium.

本文主要讨论了热密π介子环境中的ρ介子谱函数。

Since ρ〓,ω are neutral vector mesons, the G-parity breaking is caused by the isospin symmetry breaking. We study the form factor of π, F〓, which is an important observable related to ρ〓-ω mixing problem.

在这个问题中，由于ρ〓，ω都是中性矢量介子，因此G宇称的破坏主要是由同位旋对称性破缺引起，在讨论这个问题时我们首先讨论了对ρ〓-ω问题有重要意义的π介子的电磁形状因子F〓。

Our paper is organized as follows: lIn the quarkonium-quarkonium mixing scheme, we predict the mass of isoscalar of the 3~1S_0 nonet(1900±12MeV).

在这里，我们主要做了三方面的工作：1在介子—介子混合框架下，估计了3~1S_0介子九重态中同位旋标量态？

In this scheme there exist a vector nonet similar to the famous scalar nonet α_0(980,f_0(980),κet al, the masses of members of the nonet are estimated, the decay of the nonet is analyzed in detail, it can decay into two pseudoscalars or one pseudoscalar and one vector meson.

我们估计了该九重态中每个成员的质量，在"fall apart"衰变机制下仔细考察了它们的衰变，它可以衰变到两个赝标介子或者一个赝标介子和一个矢量介子。

In the chiral SU(3) quark model, we use the coupling between quarks and nonet scalar meson fields and nonet pseudo-scalar meson fields to describe the medium and long range interactions, and use one gluon exchange to describe the short range interaction. In the extended chiral SU(3) quark model, besides the nonet pseudo-scalar meson fields and the nonet scalar meson fields, the coupling between vector meson fields and quarks is also considered, the short range interaction can be dominately described by vector meson exchange. We investigate the nucleon-hyperon interaction in the extended chiral SU(3) quark model and study the S-wave phase shifts of N-Λ and N-Σ systems. Comparing to the results in chiral SU(3) quark model, we find that the short-range interaction could be described either by the one-gluon exchange or vector meson exchange.

在手征SU(3)夸克模型中，用夸克与标量介子九重态和赝标介子九重态场的耦合来描述中长程相互作用，单胶子交换来描述短程相互作用，推广的手征SU(3)夸克模型是在原来手征SU(3)夸克模型的基础上进一步引入了夸克和矢量介子九重态场的耦合，主要由矢量介子交换来描述短程相互作用，在推广手征SU(3)夸克模型下研究了核子－超子相互作用过程，计算了N-Λ和N-Σ相互作用的S波散射相移，通过和手征SU(3)夸克模型的结果比较，发现N-Λ和N-Σ系统的短程相互作用既可以由单胶子交换来描述，也可以由矢量介子交换来描述。

Ideally, they would use muons but, in practice, they are using a close cousin, the pion.

选用μ介子是最理想的，但在实验中使用的是与之很相似的介子。

The reasons of our choice are:(1) the coupling of the electromagnetic field with the matter is universal and there is already some experiences with such a kind of field in the literature;(2) the pion is the lightest hadron and its interaction with other fields are known to some extent. The pion fields have been treated as external fields but the discussion is not comprehensive in the literature.

我们选取这样的外场的理由如下：(1)电磁场与物质相互作用的耦合常数是普适的，而且文献中已经有把电磁场当作外场来处理的经验；(2)π介子是最轻的强子，它与其它场的相互作用人们已经有所了解，文献中也有把π介子场当作外场来处理的例子，但讨论还不够深入。

In the quarkonium-quarkoniumglueball mixing scheme, we quantitatively present the quarkonia-glueball content of the isoscalar scalar states and the isoscalar pseudoscalar states, and find that it is necessary to introduce additional glueball components in the ground isoscalar pseudoscalar mesons.

在介子—介子—胶球混合的框架下，我们定量地给出了同位旋为零的标量态和同位旋为零的赝标态的夸克-胶球内容，发现基态同位旋为零的赝标介子中有必要引入附加的赝标胶球成分，标量介子和标量胶球间存在强烈的混合。

These effective coupling constants of mesons embody the feature of theDBHF results, such as short-range correlations and the structure of isospin. In general,the effective meson coupling constants are weakly density dependent.

我们得到的介子耦合常数具有弱的密度依赖行为，δ和ρ介子的有效相互作用强度远小于在平均场中起主要作用的σ和ω介子。

In the "indirect" process, first observed in neutral kaon particles in 1964, quantum mechanics allows particles to change into their antiparticles and back again in a process known as "mixing". In 2001, The BaBar team, working at the Stanford Linear Accelerator -- and independently the Belle collaboration at the KEK laboratory in Japan -- were the first experiments to detect this in a B meson. BaBar observed "direct" CP violation in 2004 by showing that the number of decays observed for B mesons was higher than for their antiparticle equivalents.

在&间接&过程中，量子力学允许粒子在一种被称为&混合&的过程中，在自身与其反粒子之间相互转变。1964年人们第一次在中性K介子上观测到这种现象。2001年，在斯坦福直线加速器中心工作的BaBar研究组和另一个日本高能加速器研究中心的Belle研究小组各自独立地第一次在实验中观测到这种现象发生在B介子上。2004年，BaBar小组观测到了&直接&电荷宇称不守恒，他们发现观察到的B介子的衰变数量要高于其对应的反物质。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。