正反重强子对构成的强子分子态能谱（英文）

近二十年来,世界上众多高能物理实验发现了大量超出传统夸克模型的共振结构。为了理解这些性质奇特的共振结构,科学家们提出了很多方法和模型。其中,因为实验上发现的这些奇特态大多处在一对强子阈值附近,强子分子态的观点得到了很多关注。本文我们将以粲–反粲强子对为例来探究哪些系统可以形成分子态,进而给出粲–反粲强子分子态的能谱。我们考虑了所有由S波粲介子、粲重子以及窄的P波粲介子构成的粲–反粲强子对。我们假定它们之间的相互作用由介子交换主导,在最低阶近似下可简化为常数。通过求解常数相互作用的Bethe–Salpeter方程,我们可以找到振幅的极点进而确定该系统分子态的质量。最终我们发现,那些通过轻矢量介子交换在阈值附近产生吸引力的系统,会存在一个靠近阈值的极点。不同的系统,由于其相互作用强度不同,极点可能会处于能量复平面的第一黎曼面或者第二黎曼面,分别对应于束缚态或者虚态。我们总共发现了229个强子分子态。很多实验上发现的那些位于粲–反粲强子对阈值附近的共振结构可以很好地与我们的结果吻合。另外,我们需要强调所预言的一个ΛcˉΛc分子态,这个态可以很好地解释北京正负电子谱仪(BESIII)上测量的数...     

正反重强子对构成的强子分子态能谱

近二十年来,世界上众多高能物理实验发现了大量超出传统夸克模型的共振结构。为了理解 这些性质奇特的共振结构,科学家们提出了很多方法和模型。其中,因为实验上发现的这些奇特态 大多处在一对强子阈值附近,强子分子态的观点得到了很多关注。本文我们将以粲{反粲强子对为例 来探究哪些系统可以形成分子态,进而给出粲{反粲强子分子态的能谱。我们考虑了所有由 S 波粲 介子、粲重子以及窄的 P 波粲介子构成的粲{反粲强子对。我们假定它们之间的相互作用由介子交 换主导,在最低阶近似下可简化为常数。通过求解常数相互作用的 Bethe---Salpeter 方程,我们可以 找到振幅的极点进而确定该系统分子态的质量。最终我们发现,那些通过轻矢量介子交换在阈值附 近产生吸引力的系统,会存在一个靠近阈值的极点。不同的系统,由于其相互作用强度不同,极点 可能会处于能量复平面的第一黎曼面或者第二黎曼面,分别对应于束缚态或者虚态。我们总共发现 了 229 个强子分子态。很多实验上发现的那些位于粲---反粲强子对阈值附近的共振结构可以很好地 与我们的结果吻合。另外,我们需要强调所预言的一个 ΛcΛc  分子态,这个态可以很好地解释北京正负电子谱仪 (BESIII) 上测量的数据。     

J/ψ强子衰变和1－+奇特态

本文从推广的矩分析出发,给出了在J/ψ强子衰变过程中区分1^－+奇特态和1⁺⁺普通介子的若干关系式.     

三角奇点与XYZ类粲偶素结构

对强子谱的研究有助于加深量子色动力学中色禁闭现象的理解。强子谱中存在诸多疑难问题,特别是2003年以来各高能物理实验上发现了很多难以理解的新的强子共振结构,其中大量是在重夸克偶素质量区间发现的,它们被统称为$XYZ$结构。强子共振态对应于$S$矩阵的极点。除此之外,$S$矩阵还具有其它类型的奇点,比如由于三个中间态粒子同时在 壳导致的三角奇点。本文中,我们将讨论三角奇点在$XYZ$物理中的实现,注重于构造可以用来分析 其对$e^+e^-\to\psi\pi^+\pi^-$反应的$\psi\pi$不变质量谱中的带电$Z_c$结构的影响的振幅。     

HERMES五夸克强子态Θ+实验探索

一个新的强子态的实验证据在2?7.6GeV正电子轰击氘靶产生的虚光子产物中被发现.HERMES通过分析衰变道K0sp→π+π–p,在K0sp不变质量谱上质量1528±2.6(stat.)±2.1(sys.)MeV处观察到共振峰.该共振峰可以被解释为理论预言的五夸克强子态Θ+(uudds).而K+p不变质量谱上未能观察到共振预示Θ+很可能是同位旋单态.     

发现ZC（3900）--一个带电类粲偶素共振结构*

北京谱仪(BESⅢ)实验和Belle实验利用两种不同的方法对e+e-→p+p-J/y过程进行了研究。在p±J/y系统中,同时观测到了一个新的带电类粲偶素结构--ZC(3900)。ZC(3900)耦合到粲偶素末态,因此其内部夸克组分应该含有正反粲夸克;同时它还带有电荷,故不可能仅由正反粲夸克组成。ZC(3900)共振态中最少含有4个夸克,极有可能是一个奇特态强子。     

五夸克态进展

对2003年和2004年强子物理研究中的热点——五夸克态,从实验进展和理论研究上进行了较为详细的介绍,对研究的现状进行了评价和展望,同时介绍了国内一些研究小组在五夸克态研究中做出的贡献.     

部分子末态的色分离联接对e+e－反应中强子产额及其动量谱的影响

用JETSET事例产生器对e⁺e^－→qq+ng→hadrons反应中,末态部分子(qq+ng)以色分离的联接方式进行强子化时,各种强子产额及π⁺,K^±,p/p的动量谱进行了计算;与传统的色中性流联接方式强子化结果进行比较.结果表明:由T权重确定的色分离单态和色中性流这两种完全不同的色联接方式强子化得到的强子产额及π⁺,K^±,p/p的动量谱,与实验符合的程度相同,有些更好.     

BESⅢ实验首次观测到Y(4260)→γX(3872)辐射跃迁

<正>随着我国北京正负电子对撞机(BEPCII)上的北京谱仪(BESIII)实验和日本高能加速器研究机构(KEK)的Belle实验发现带电奇特强子态ZC(3900)[1],研究奇特态粒子成为粒子物理学研究领域中当前最热门的课题之一。究竟什么是奇特态粒子呢?这还得追溯到基本粒子的结构。     

兰州冷却储存环上可开展的强子物理研究

介绍了当前强子物理的研究现状和兰州冷却储存环的能量特点,以及国内强子物理专家的分析和建议。在兰州冷却储存环上,可利用中能轻离子束核反应产生强子激发态研究强子内部夸克态的结构和性质、强子性质随核环境的变化和手征对称破缺与部分恢复。尤其是通过兰州冷却储存环上限能区附近的P＋P反应,研究奇异夸克的不对称性和形状因子,寻找超子激发态和pentaquark的实验证据,发现双重子态的实验事例。 According to both the development on badrons physics and the aspect of Lanzhou cooling storage ring （CSR） and based on the analysis and propositions given by experts in China, we propose some hadrons physics program at CSR. The hadron spectroscopy produced in light nucleus collisions at CSR used to probe the quark and gluon structure of hadrons, to study the modification of the hadron properties in nuclear matter and to investigate the spontaneous breaking of the chiral symmetry and its partial restoration. Especially, the proton-proton collisions at beam energies per proton below 2.8 GeV at CSR should be used to measure the strangeness asymmetry and strange form lector, to probe the existence of hyperon and pentaquarks and to find the evidence for the existence of dibaryon.     

Progress in p-shell A hypernuclear spectroscopy

The strangeness nuclear physics is an important branch of nuclear physics. The spectroscopic study of A hypernuclei has been used as a tool for investigating the A-N interaction as well as probing the nuclear interior structure. In this paper some high-lights and open questions in the spectroscopic study of p-shell A hypernuclei are presented.     

转筒法测液体黏度关系式比较研究

对文献中转筒法测液体黏度的几个关系式进行了比较研究,指出了其中的问题.     

Genetic optimisation of a neural damage locator

A critical problem in structural health monitoring (SHM) based on pattern recognition methods is the correct selection of features, i.e. measured and processed data for the diagnosis. Various selection strategies have been applied in the past and one approach that has proved effective is the use of combinatorial optimisation methods. This paper presents a case study based on a scheme for damage location in an aircraft wing. The feature selection algorithm is a Genetic Algorithm and the locator (classifier) is an artificial neural network. A comparison is made with the results obtained when the features are selected on the basis of engineering judgement. The study is seen to raise some issues relating to model complexity and generalisation and these matters are discussed in some detail.     

A method for SEM analysis of matrix oil

In some cases, there are difficulties in study of the morphological forms of the matrix oil present in carbonate rocks of some deposits by scanning electron microscopy. A method is proposed for studying rock cleavages in a scanning electron microscope at different accelerating voltages, which makes it possible to identify matrix oil by selecting the phase with a high content of light elements (carbon).     

String theory in five dimensional cosmological models

A study on string theory has been done in five dimensional flat space-time. Barotropic equation of state andp-string model are discussed. Also a polynomial relation between the two scale factors is assumed. In some special cases the solution reduces to generalized Kasner metric. Further diminision of extra dimension with the evolution of universe is exhibited. A detailed study of phase-space analysis is done for geometric string model.     

Review of Tm and Ho materials; spectroscopy and lasers

A review of Tm and Ho materials is presented, covering some fundamental aspects on the spectroscopy and laser dynamics in both single and co-doped systems. Following an introduction to 2-μm lasers, applications and historical development, the physics of quasi-four level lasers, energy transfer and modeling are discussed in some detail. Recent developments in using Tm lasers to pump Ho lasers are discussed, and seen to offer some advantages over conventional Tm:Ho lasers. This article is not intended as a complete review, but as a primer for introducing concepts and a resource for further study.     

Simulation of Mode Interaction in the Gyrotron FU CW I

A series of experiments carried out in order to study the operational performance and oscillation characteristics of a 300 GHz/3.5 kW gyrotron FU CW I have demonstrated a complicated behaviour which is attributed to multimoding phenomena. In this paper we present and discuss some initial results from computer simulation of mode interaction in this tube. They give a better insight in the underlying processes, possible excitation conditions of various competing modes and suggest some directions for continuation of this investigation.     

The influence of cascade on the polarization of radiation produced in electronic or atomic collisions

A study is presented, in which we consider the influence of cascade effects on the polarization of light emission produced in electronic or atomic collisions. Cascade transitions are shown to cause a polarization transfer which may result in a total falsification and even in a sign reversal of the polarization. Closed expressions are derived for some special cases. A practical application is given in which the derived formulas are used to understand a serious discrepancy between theoretical predictions and experimental data in the case of the line polarization due to some 3p-3s transitions in neon induced by proton impact.     

Scattering Problem for Local Perturbations\newline of the Free Quantum Gas

A Harnack type inequality is established for solutions to some semilinear elliptic equations in dimension two. The result is motivated by our approach to the study of some semilinear elliptic equations on compact Riemannian manifolds, which originated from some Chern–Simons Higgs model and have been studied recently by various authors. Received: 30 September 1997 / Accepted: 21 July 1998