带费米子2+1维SU(20)群格点规范理论中的真空和手征对称性自发破缺

本文把纯规范场的严格基态和费米场的变分真空态结合起来,研究格点QCD中2+1维SU(20)群带费米子的真空结构,计算费米子真空凝聚<ψψ>,其结果有较好的标度行为.     

粒子数表象中的算符(费米子)

根据多粒子体系的算符对波函数的作用讨论费米子体系粒子数表象的算符,并给出费米子体系粒子数表象的角动量算符.     

IBFM中费米子算符的表达式

本短文给出了包含g玻色子的IBFM中费米子算符的表达式.     

低维规范理论中的费米子真空凝聚

我们把么正变换、变分法和纯规范场准确基态结合在一起,系统研究(1+1)维和(2+1)维带费米子格点规范理论的真空结构和手征对称性自发破缺,得到〈ψψ〉深入到弱耦合区的标度行为.本文结果与连续Schwinger模型一致,并预言了QCD₂、QED₃和QCD₃的费米子真空凝聚值.     

有限温下三维QED中费米速度对费米子手征凝聚的影响（英文）

三维QED 具有两个和QCD类似的性质:动力学手征对称破缺和禁闭。为了研究动力学手征对称破缺，基于彩虹近似，在Dyson-Schwinger 方程框架下，通过迭代求解有限温下的费米子自能方程，讨论了不同的费米速度下费米子手征凝聚与费米子味数之间的关系。发现在有限温下，对于固定的费米子味数，费米手征凝聚随费米速度的变大而单调减小。Analogous to Quantum QCD, QED₃ has two interesting features: dynamical chiral symmetry breaking (DCSB) and confinement. By adopting the rainbow approximation, we numerically solve the fermion self-energy equation at finite temperature in the framework of Dyson-Schwinger equations and discuss the relation between chiral condensate and fermion flavor for several fermion velocities in the finite temperature QED₃. It is found that the fermion chiral condensate decreases monotonically with the fermion velocity increasing for a fixed N at finite temperature.     

多个含不同质量项的费米子矩阵求逆算法

在格点量子色动力学的模拟中,Rational Hybrid Monte Carlo (RHMC)算法是一种精确的,能应用到任意多个味道数的费米子的方法.它的思想是把费米子行列式展开为有理函数的形式.但该方法会带来很多彼此相差一个常对角矩阵的矩阵的求逆的计算,消耗大量的时间和计算资源,限制了RHMC算法的应用.本文利用移位多项式,针对共轭梯度法得到多个含有不同质量项的矩阵求逆的一种方法,该方法可以应用到RHMC算法中.     

可解的1+1维格点U(1)规范模型与费米子加倍问题

本文准确求解了一个有费米子加倍的格点U(1)规范模型.结果显示正反费米子组成的介子态出现相应的加倍问题.进一步,我们证明Susskind费米方案可以消除介子态的加倍.     

Tsvelik—Reizer唯象模型中的非费米液体行为

我们研究了电子比热、直流电阻率、电子磁化率在非费米液体重费米子体系的Ｔｓｖｅｌｉｋ－Ｒｅｉｚｅｒ唯象模型中表现出的非费米液体行为。考虑到电子与集体激发的相互作用，在低频和长波长极限下，在单圈图近似内我们首先计算了电子自能，得到与边缘费米液体理论中的电子自能非常相似的结果。利用电子自能的结果，我们计算了电子比热，发现从Ｔｓｖｅｌｉｋ－Ｒｅｉｚｅｒ模型得到的电子比热与非费米液体重费米子体系上的实验结果     

在(2+1)维手征Gross-Neveu模型中有限温度的顶角修正和退耦合相变

本文根据含复合场的Wark-Takahashi恒等式所得到的费米子质量谱,利用虚时温度场论计算了准确到1/N阶的费米子和σ介子的顶角修正,并讨论了顶角函数随温度的变化关系和退耦合相变.结果表明:退耦合相变的临界温度随着零下π介子和费米质量的增大而升高,由热涨落对顶角修正所引起的费米子质量的改变不能忽略.     

用改进的哈密顿量计算Wilson费米子真空凝聚

用改进的哈密顿量和变分法计算格点(1+1)维QED(Schwinger模型)中Wilson费米子真空凝聚<ψψ>，结果(同使用未改进的哈密顿量的计算结果相比较)与Wilson参数r的依赖关系明显地减小了.     

Topological susceptibility from overlap fermion

We numerically calculate the topological charge of the gauge configurations on a finite lattice by the fermionic method with overlap fermions. By using the lattice index theorem, we identify the index of the massless overlap fermion operator to the topological charge of the background gauge configuration. The resulting topological susceptibility χ is in good agreement with the anticipation made by Witten and Veneziano.     

Calculation of CWKB envelope in boson and fermion productions

We present the calculation of envelope of boson and of both low-and high-mass fermion production at the end of inflation when the coherently oscillating inflatons decay into bosons and fermions. We consider three different models of inflation and use CWKB technique to calculate the envelope to understand the structure of resonance band formation. We observe that though low-mass fermion production is not effective in preheating because of Pauli blocking, it is quite probable for high-mass fermion to take part in pre-heating.      

The Relativistic Covariance of the Fermion Green Function and Minimal Quantization of Electrodynamics

This paper is devoted to the one-loop calculation of the fermion Green function in QED within the framework of the minimal quantization method,based on an explicit solution of the constraint equations and the gangeinvariance principle.The relativistic invariant expression for the fermion Green function with correct analytical properties is obtained.     

Quantization of relativistic systems with boson and fermion first- and second-class constraints

The general solution for the S matrix of an arbitrary Hamilton system with boson and fermion first- and second-class constraints of general form is obtained. Additional diagrams arise securing unitary and gauge invariance of the theory: the many-particle interaction of fermion and boson ghosts. The generalized Ward identities are obtained.     

Finite-mode regularization of the fermion functional integral

We present a regularization of the fermion functional integral in the presence of a gauge field, obtained by projecting the fermion fields on a finite subspace of the fermion wave functions. We find the basis that ensures manifest gauge covariance. We are able, in this way, to develop a non-perturbative method of calculation and test it by calculating the triangle anomalies in different models. All the calculations are carried out on a finite-size momentum space lattice. Finally we briefly discuss the zero-mode problem.     

Anomalous Dimensions of Quark Masses in the Three-Loop Approximation

Physics of Particles and Nuclei Letters - The results of calculation of the three-loop radiative correction to the renormalization constant of fermion masses for non-abelian gauge theory...     

Monte Carlo calculation of the thermodynamic properties of a one-dimensional fermion lattice model

The generalized Trotter formula is used to derive two different classical representations of the partition function of a one-dimensional fermion model. Shortchain calculations are used to study the corresponding approximants for the energy and specific heat. A Monte Carlo technique has been used to calculate the temperature-dependent properties of a chain of 64 sites.     

Composite fermion picture for multi-component plasmas in 2D electron–hole systems in a strong magnetic field

Low-lying states of a 2D electron–hole system contain electrons and one or more types of charged excitonic complexes. Binding energies and angular momenta of these excitonic ions, and the pseudopotentials describing their interactions with electrons and with one another are obtained from numerical studies of small systems. Incompressible fluid ground states of such multi-component plasmas are found in exact numerical diagonalizations. A generalized composite fermion (CF) picture involving Chern–Simons charges and fluxes of different types is proposed and shown to predict the low-lying states at any value of the magnetic field.     

Gauge Covariant Fermion Propagator in the Presence of Arbitrary External Gauge Field and Its Schwinger--Dyson Equation

Gauge covariance for Green＇s functions of a gauge theory through a fermion propagator in the presence of arbitrary external gauge field is proven and a formalism of gauge and Lorentz covariant Schwinger-Dyson equation for the fermion propagator with external gauge field is built up within ladder approximation.