共查询到18条相似文献,搜索用时 78 毫秒
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基于关联度概念,建立了可以分别检测高阶集合流的主位角关联、横向动量模关联和横向关联的新方法。采用新方法分别分析了1.2A GeVAr BaI2的碰撞的Bevalac流光室4π实验事件中末态粒子分布的方位角关联与粒子横向动量模的关联对高阶集合流关联的贡献。研究表明:对于这组碰撞实验,末态粒子分布的方位角关联相对横向动量模的关联在高阶集合流关联中起主要作用;末态粒子横向动量模的关联不但可以使粒子群高队关联的强度有所增加,而且还为在更为狭窄的区间上确定集合流集体性的范围提供了重要信息。 相似文献
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相对论重离子碰撞中集合流的横向运动关联 总被引:2,自引:0,他引:2
本文对1.2AGeV Ar+BaI2和2.1 AGeV Ne+NaF碰撞的Bevalac流光室4π实验数据进行了集合流横向运动关联特性的研究.研究表明,末态粒子的横向运动不仅存在粒子分布的方位角关联,而且还存在横向动量模的关联;Ar+BaI2碰撞实验中粒子分布的方位角关联、横向动量模关联和横向运动关联都分别强于Ne+NaF碰撞实验中相对应的各种关联;对于这两组碰撞实验,粒子分布的方位角关联相对横向动量模关联在横向运动关联中起着主要作用. 相似文献
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我们给出了一种分析集合流的n粒子横向关联函数方法,把对n粒子方位角关联的研究和集体性的计算推广到能够同时利用横向动量大小和方位角信息的情形.对于确定集合流的集体性而言,这种方法比仅仅利用方位角信息的多粒子方位角关联方法更为敏感.采用这种新方法,分析了Bevalac流光室1.2A GeV Ar+KC1碰撞中n粒子的横向关联,与蒙特卡罗模拟结果的对比推算了该碰撞中末态粒子的集体性是介于85%~95%之间. 相似文献
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高能重离子碰撞中末态粒子的关联度与集合侧向流 总被引:1,自引:0,他引:1
提出了关联度概念,采用粒子群关联函数方法对Bevalac流光室1.2A GeV Ar+BaI2碰撞事件中关联度不同的粒子对集合侧向流的作用进行了研究.研究表明:关联度是描述集合侧向流性质的一个重要参量.少数关联度较大的粒子(或碎片)可以产生集合侧向流效应,但高阶集合流关联却不受其支配,而是关联度不同的多数粒子(或碎片)集体贡献的结果. 相似文献
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2.1A GeV Ne+NaF碰撞中的粒子群关联与集体性 总被引:1,自引:1,他引:0
提出了粒子群关联概念,并以此建立了一种检测集合流的新方法,采用新方法对2.1A GeV Ne+NaF碰撞的Bevalac流光室4π实验事件粒子群的关联进行了研究.通过与蒙特卡罗结果进行比较,推测该实验事件集合流的集体性约在75%-95%之间. 相似文献
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2.1AGeVNe NaF碰撞中的粒子群关联与集体性 总被引:1,自引:0,他引:1
提出了粒子群关联概念,并以此建立了一种检测集合流的新方法,采用新方法对2.1AGeVNe+NaF碰撞的Bevalac流光室4π实验事件粒子群的关联进行了研究.通过与蒙特卡罗结果进行比较,推测该实验事件集合流的集体性约在75%-95%之间。 相似文献
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L.B.Weinstein 《中国物理C(英文版)》2010,34(9)
Studying nucleon-nucleon (NN) correlated pairs will teach us a great deal about the high momentum part of the nuclear wave function, the short range part of the NN interaction, and the nature of cold dense nuclear matter. These correlations are similar in all nuclei, differing only in magnitude. High momentum nucleons, p > pfermi, all have a correlated partner with approximately equal and opposite momentum. At pair relative momenta of 300 < prel < 500 MeV/c, these correlated pairs are dominated by tensor correla-tions. This is shown by the dominance of pn over pp pairs at pair total momentum and by the parity of pn to pp pairs at large pair total momentum. 相似文献
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L. B. Weinstein 《中国物理 C》2010,34(9):1224-1228
Studying nucleon-nucleon (NN) correlated pairs will teach us a great deal about the high momentum part of the nuclear wave function,the short range part of the NN interaction,and the nature of cold dense nuclear matter.These correlations are similar in all nuclei,differing only in magnitude.High momentum nucleons,p 〉p fermi,all have a correlated partner with approximately equal and opposite momentum.At pair relative momenta of 300 〈prel 〈500 MeV/c,these correlated pairs are dominated by tensor correlations.This is shown by the dominance of pn over pp pairs at pair total momentum and by the parity of pn to pp pairs at large pair total momentum. 相似文献
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Based on an open exactly solvable system coupled to an environment with nontrivial spectral density, we connect the features of quantum and classical correlations with some features of the environment, initial states of the system, and the presence of initial system–environment correlations. Some interesting features not revealed before are observed by changing the structure of environment, the initial states of system, and the presence of initial system–environment correlations. The main results are as follows. (1) Quantum correlations exhibit temporary freezing and permanent freezing even at high temperature of the environment, for which the necessary and sufficient conditions are given by three propositions. (2) Quantum correlations display a transition from temporary freezing to permanent freezing by changing the structure of environment. (3) Quantum correlations can be enhanced all the time, for which the condition is put forward. (4) The one-to-one dependency relationship between all kinds of dynamic behaviors of quantum correlations and the initial states of the system as well as environment structure is established. (5) In the presence of initial system–environment correlations, quantum correlations under local environment exhibit temporary multi-freezing phenomenon. While under global environment they oscillate, revive, and damp, an explanation for which is given. 相似文献
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A unified approach valid for any wavenumber q, frequency ω, and temperature T is presented for uniform ideal quantum gases allowing for a comprehensive study of number density and particle-current density response functions. Exact analytical expressions are obtained for spectral functions in terms of polylogarithms. Also, particle-number and particle-current static susceptibilities are presented which, for fugacity less than unity, additionally involve Kummer functions. The q- and T-dependent transverse-current static susceptibility is used to show explicitly that current correlations are of long range in a Bose-condensed uniform ideal gas but for bosons at T>Tc and for Fermi and Boltzmann gases at all temperatures these correlations are of short range. Contact repulsive interactions for systems of neutral quantum particles are considered within the random phase approximation. The expressions for particle-number and transverse-current susceptibilities are utilized to discuss the existence or nonexistence of superfluidity in the systems under consideration. 相似文献
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We investigate the decay of initial correlations in a spin system where each spin relaxes independently by an intramolecular mechanism. The equation of motion for the spin density matrix is assumed to be the Redfield equation, which is of the form of a quantum mechanical master equation. Our analysis of this problem is based on the techniques of Shuler, Oppenheim, and coworkers, who have studied the decay of correlations in systems which can be described by classical stochastic master equations. We find that the off-diagonal elements of the reduced spin density matrices approach their equilibrium values faster than the diagonal elements. The Ursell functions, which are a measure of the correlations in the system, decay to their zero equilibrium values faster than the spin density matrix except for the furthest off-diagonal elements. Far off-diagonal matrix elements of the spin density matrix approach equilibrium at the same rate as the Ursell functions, which is the important difference between the quantum mechanical model studied here and the classical models studied earlier.Supported in part by the National Science Foundation. 相似文献
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LUO Shun-Long LI Nan 《理论物理通讯》2008,49(2):327-328
Werner states are paradigmatic examples of quantum states and play an innovative role in quantum information theory. In investigating the correlating capability of Werner states, we find the curious phenomenon that quantum correlations, as quantified by the entanglement of formation, may exceed the total correlations, as measured by the quantum mutual information. Consequently, though the entanglement of formation is so widely used in quantifying entanglement, it cannot be interpreted as a consistent measure of quantum correlations per se if we accept the folklore that total correlations are measured (or rather upper bounded) by the quantum mutual information. 相似文献
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B. Jancovici 《Journal of statistical physics》1995,80(1-2):445-459
From the laws of macroscopic electrostatics of conductors (in particular, the existence of screening), taken as given, one can deduce universal properties for the thermal fluctuations in a classical Coulomb system at equilibrium. The universality is especially apparent in the long-range correlations of the electrical potentials and fields. The charge fluctuations are derived from the field fluctuations. This is a convenient way to study the surface charge fluctuations on a conductor with boundaries. Explicit results are given for simple geometries. The potentials and the fields have Gaussian fluctuations, except for a short-distance cutoff.laboratory associated with the Centre National de la Recherche Scientifique. 相似文献
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《The European Physical Journal A - Hadrons and Nuclei》2005,23(2):271-278
Small-angle correlations of pairs of protons emitted in central collisions of Ca + Ca, Ru + Ru and Au + Au at beam energies from 400 to 1500MeV per nucleon are investigated with the FOPI detector system at SIS/GSI Darmstadt. Dependences on system size and beam energy are presented which extend the experimental data basis of pp correlations in the SIS energy range substantially. The size of the proton-emitting source is estimated by comparing the experimental data with the output of a final-state interaction model which utilizes either static Gaussian sources or the one-body phase-space distribution of protons provided by the BUU transport approach. The trends in the experimental data, i.e. system size and beam energy dependences, are well reproduced by this hybrid model. However, the pp correlation function is found rather insensitive to the stiffness of the equation of state entering the transport model calculations. 相似文献