共查询到17条相似文献，搜索用时 46 毫秒
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基于三维量子电动力学理论,用截断的Dyson-Schwinger(D-S)方程研究带有真空极化效应的光子传播子和费米传播子.数值计算表明,凝聚和费米质量的数值取决于截断方案.在有限耦合D-S方程基础上,还发现费米传播子函数明显依赖于序参量ξ.采用非淬火近似,利用截断的费米子所满足的D-S方程研究了费米子手征凝聚和费米子... 相似文献
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由于低能区域内的非微扰效应不能忽略,使得QCD在处理粒子物理中的强子问题时非常困难,而QED有较成熟的非微扰模型,可以很好地处理夸克和胶子传播子在费米作用能方面的相关问题,因此本文采用QED,来处理费米凝聚问题．首先构建费米子所满足的Dyson-Schwinger方程,然后求解费米能隙．理论计算表明,在手征极限下该能隙方程存在3个解,而在超越手征极限下则存在2个解,这些解都对应于不同的费米凝聚．手征极限下的费米凝聚可用来分析3个相的存在,即反铁磁相、赝能级和超导态．而在超越手征极限下,发现存在2个费米子凝聚． 相似文献
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石远美 《南京晓庄学院学报》2012,(3):24-27
在QCD的DS方程方法框架下,文章研究了夸克-胶子顶点的着衣效应对夸克传播子的影响,也就是超越彩虹近似,利用BC顶点以及CP顶点对夸克传播子进行了系统的研究.结果发现,不论采用什么夸克-胶子顶点,夸克传播子在高动量区域趋于裸的夸克传播子,这个结论符合QCD的＂渐近自由＂特性.而在小动量区域,夸克传播子的着衣效应很大,出现了手征对称性自发破缺,夸克在低动量区域获得了很大的质量,并且不同的夸克-胶子顶点对夸克传播子的低动量区域的着衣效应差别很大. 相似文献
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单石墨层(graphene)的制备和其中的新奇物理现象的研究是近几年凝聚态物理学的主要热点之一.这种材料电子能谱具有与无质量Dirac费米子相同的形式,其波函数是手征的.本文研究了调制电磁场对单石墨层电子结构的影响,计算了Lan-dau子能带的带宽和态密度,对电子结构的Weiss振荡与外参数的关系进行了考察.结果可用于gaphene在调制外场中的输运性质的研究. 相似文献
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该文采用基于密度泛函理论的赝势平面波方法,为了探索Li3N材料的相变路径,系统地研究了Li3N材料常压相结构（α-Li3N）的动力学稳定性．同时,根据Landau理论,提出了一个新的动力学稳定的高压相结构,其空间群为P-3ml． 相似文献
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具有极大磁电阻的半金属材料因其可能具有非寻常的拓扑电子结构、电输运特性,可为高能物理相关的狄拉克费米子、外尔费米子以及马约拉纳费米子的研究提供崭新的舞台,受到了广泛关注.本文通过助溶剂法合成高质量的GdSb单晶并系统地研究其结构、磁性、电输运等性质,发现该材料具有NaCl型晶体结构(空间群Fm-3m),并且在23.4 K附近经历反铁磁相变.电输运结果表明GdSb具有金属导电性,自旋无序效应可导致磁相变温度附近的电阻出现异常.更吸引人的是,样品在磁场(H=9 T)作用下,低温(2 K)电阻将出现平台,展示出极大的磁电阻效应(MR=12 100%).通过霍尔效应及第一性原理计算,发现GdSb是多带及补偿型半金属,其中电子与空穴的数目相当.电子-空穴补偿及较大的载流子迁移率是极大磁电阻的来源. 相似文献
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Maxwell理论电磁对偶性的费米子表述 总被引：3，自引：0，他引：3
王剑华 《陕西教育学院学报》2003,19(1):76-79
通过引入复量场F=E-iB,给出了无源Maxwell方程组的电磁对偶对称性的费米子表述形式.接着给出了有源情况下Maxwell方程的费米子表述形式.在有源情况下必须引入Dirac磁单极而且这一描述形式具有洛伦兹协变性和电磁对偶性. 相似文献
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本文首先介绍了对易空间中的Wigner函数和Moyal本征方程;然后从Moyal-Weyl乘法出发利用Bopp变换给出了非对易空间中Wigner函数所服从的Moyal方程;最后计算了非对易空间中谐振子的Wigner函数。 相似文献
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崔海涛 《安阳师范学院学报》2011,(5):9-13
通过对量子态对称性的要求,本文提供了对N-量子比特多体纠缠态的一种可能分类。对称基可以被建立起来,通过两个整体特征：周期结构和循环单元,对称基底态可以分为若干类。并与相变现象类比,重新建立了对纠缠态等价性质的理解：不等价的纠缠态对应不同的相,他们之间的转变必然伴随相变现象。除此之外,包含不同相的量子态被归为对称破缺相。 相似文献
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Solitons emerge as non-perturbative solutions of non-linear wave equations in classical and quantum theories. These are non-dispersive
and localised packets of energy — remarkable properties for solutions of non-linear differential equations. In the presence
of such objects, the solutions of Dirac equation lead to the curious phenomenon of ‘fractional fermion number’. Under normal
conditions the fermion number takes strictly integral values. In this article, we describe this accidental discovery and its
manifestation in polyacetylene chains, which has led to the development of organic conductors.
(left) Kumar Rao is a Postdoctoral Fellow at PRL, Ahmedabad. He is interested in particle physics phenomenology as probed
in particle colliders and formal aspects of quantum field theory.
(right) Narendra Sahu is currently a postdoctoral fellow at Lancaster University, UK. His main research area includes Cosmology
and Astroparticle physics. Currently he is working on dark matter and matter anti-matter asymmetry of the universe.
(center) P K Panigrahi’s research interests are in the area of quantum computation, solitons in Bose Einstein condensates
& nonlinear optical media. He is also deeply interested in science education and derives pleasure from long weekend walks. 相似文献
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The literature suggests that radical changes to teacher education are common but rarely well-planned or resourced. Such changes can be detrimental to the quality of learning and it is challenging for educators to know how to respond. Joseph Schwab argued that for balanced curriculum development to occur, deliberation must take place with the four commonplaces (teachers, learners, subject matter and milieu). In this study, three teacher educators in a research intensive university in New Zealand were forced to combine three distinct courses (Health, Outdoor and Physical Education) into one course. Concerned that student learning would be compromised, we embarked on a series of deliberations informed by Schwab’s ideas. The deliberations involved meeting regularly over six months, inviting representatives from the commonplaces (program leaders, pedagogical specialists, pre-service teachers and teachers) into our deliberations and reflecting on the process. Analysis revealed that our deliberations could be characterized by phases: (1) creating the necessary conditions, (2) the problem emerges, (3) the solution emerges, (4) evaluation and (5) beyond deliberation. These phases of deliberation were distinguished by different concerns and timeframes and roughly reflected the stages of deliberation identified by Schwab. Convergence and divergence from Schwab’s stages are discussed. While much of Schwab’s work on deliberation remains relevant today, we recommend the addition of an initial phase focused on establishing a collaborative basis at the beginning of the process. We found this phase not only generated respect and care amongst the collaborators, but also helped frame the problem and enabled new solutions to emerge. 相似文献
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一种新型光学纯胡椒醛基氮杂环丙基羧酸酯的合成与表征 总被引：2，自引：2，他引：0
为发展新型手性配体,降低手性催化剂的合成成本,检验由芳醛与手性氨基酸酯缩合、还原反应的普适性,以L-丝氨酸为手性源,经酯化,缩合,还原氨化,关环等反应,设计合成了一种新的胡椒醛基氮杂环丙基羧酸酯5,其结构通过IR,1H NMR,13C NMR,HRMS进行了表征.发展了一条高效便捷合成这类具有光学活性化合物的方法. 相似文献
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On acquiring expertise in medicine 总被引：6，自引：0，他引：6
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本文应用统计物理的方法对一级相变中的潜热的符号进行了讨论.根据压强和温度,对相平衡曲线两侧的相加以规定,在发生相的转移时,潜热的符号具有一定的视律.并且,文章还对潜热的符号与两相共存的热容量C共存之间的关系进行了讨论. 相似文献