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The quark propagator in the Landau gauge is studied on the lattice, including the quenched and the unquenched results. No obvious unquenched effects are found by comparing the quenched quark propagator with the dynamical one. For the quenched and unquenched configurations, the results with different quark masses have been computed. For the quark mass function, a nonlinear chiral extrapolating behavior is found in the infrared region for both the quenched and dynamical results. 相似文献
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牛顿碰撞球的解释与分析 总被引:1,自引:0,他引:1
对牛顿碰撞球的常规碰撞形式和混合联珠单球碰撞形式做了理论分析和解释.在常规碰撞时,将悬线(钓鱼线)先悬挂小球一段时间后组装仪器,可克服悬线的拉力.在混合联珠单球碰撞时,根据理论分析,选取大球和小球的质量比为27∶8时,演示效果较好. 相似文献
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In this paper we calculate the equation of state (EOS) of QCD at zero temperature and finite chemical potential by using several models of quark propagators including the Dyson-Schwinger equations (DSEs) model,the hard-dense-loop (HDL) approximation and the quasi-particle model.The results are analyzed and compared with the known results in the literature. 相似文献
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Recently, Liu et al. proposed a so-called extended Anderson-Higgs mechanism by studying the (2+1)-dimensional Ginzburg-Landau model in the pseudogap region of high-Tc superconductor (Phys. Rev. B 65 (2002) 132513). We revisit this problem based on a general decomposition of the U(1) gauge potential. Using the bulk superconductor and superconduct ring as examples, we obtain a simpler expression for the extended Anderson-Higgs mechanism. In the former case we indicate that all the phase field can always be "eaten up" by the pure gauge term A||. In the latter case, we decompose the phase field as θ(x) = θ1(x) + θ2(x) and find that only the phase field θ1 connected with Anderson-Higgs mechanism can be canceled by the pure-gauge term A||. On the other hand, the remaining phase field θ2 connected with A⊥ is multi-valued, which can induce new physical effects such as A-B effect and flux quantization. It is natural to conclude that there is no longitudinal phase fluctuation effect in high-temperature superconductors since longitudinal phase θ1 is connected with pure-gauge term. 相似文献
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讨论了在方箱归一化之下的自由实标量场系统的等时对易关系,发现根据通常自由场理论的粒子解释出发,自由实标量场系统的等时对易关系,在自然数学的意义上,应该是以某一个周期性延拓形式的狄拉克δ-函数来代替通常的狄拉克δ-函数,这一点在数学上看,既是自然的,也是必然的,而在无穷体积极限之下,自由实标量场的等时对易关系可以自然的回复至标准的原有形式.本文中对于这一事实作了详细的讨论与论证,并且从物理的角度,对于场论中方箱归一化处理之物理实质内涵,作出了一定的探讨性的分析,给出了一点基本的认识. 相似文献
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It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relation. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relation, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed. 相似文献
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We use the direct method proposed by He et al. [Phys. Lett. B 680 (2009) 432) to calculate the quark-number susceptibility (QNS) at finite temperature and the chemical potential in the quasi-particle model. In our approach the QNS is given by a formula solely involving the dressed quark propagator at finite chemical potential μ and temperature Τ. The QNS at finite μ and Τ is calculated in the quasi-particle model. It is found that at high temperatures the QNS tends to the ideal quark gas result. At very small temperatures the QNS vanishes. This vanishing behavior in the low-temperature region is consistent with the lattice results. For μ∈ [0,180] MeV, our results show that there exists a rapid increase of QNS near some temperatures. The temperature at which the rapid increase occurs shifts to smaller values with the increasing quark chemical potential. This rapid increase could be regarded as a signal of a crossover. 相似文献