磁场背景下有限温度NJL模型的手征性质

研究有限温度时均匀磁场背景下NJL模型的手征性质,计算不同磁场强度时有限温度和化学势下的手征凝聚和相图.利用玻色子化方法,得到具有辅助玻色子场的NJL模型拉格朗日密度,以此研究超出平均场近似的情形.通过使用最优化微扰论(OPT)方法,在微扰展开到一阶时,计入了部分高阶效应.计算结果表明,相变的性质与该模型在平均场近似下定性一致.相变线上存在两种不同类型的相变:在高温低化学势下是平滑的过渡,在低温高化学势下是一阶相变,相变存在临界终点(CEP).磁场增强会加剧手征对称性破缺,具有磁催化作用.随着磁场增强,CEP向相图的左上方移动,即对应的临界温度升高而临界化学势降低.

NJL住宅项目定价模型分析及应用研究

文中通过对某市三大房地产板块市场状况的分析,分析房地产定价的影响因素,运用评分法对三大房地产板块的26个楼盘进行各因素评分。结合各楼盘的销售均价,分析销售均价与房地产定位的影响因素之间的关系,建立定价模型,并应用定价模型确定NJL房地产项目的销售均价。

Propagators for Scalar Bound States at Finite Temperature in an NJL Model

We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove that they are completely equivalent in the imaginary-time and real-time formalisms by separating carefully the imaginary part of the zero-temperature loop integral. It is shown that the same thermal transformation matrix of the matrix propagators for these bound states in the real-time formalism is precisely the one of the matrix propagator for an elementary scalar particle and this fact shows the similarity of thermodynamic property between a composite and elementary scalar particle. The retarded and advanced propagators for these bound states are also given explicitly from the imaginary-time formalism.

有限温度下基于NJL模型的GMOR关系研究

在量子色动力学(QCD)中,Gell-Mann-Oakes-Renner(GMOR)关系式是联系夸克凝聚、介子质量和衰变常数的一个零温下低阶近似的恒等式.本文根据QCD有效理论,从Nambu-Jona-Lasinio(NJL)模型出发,基于双味NJL模型和正时正规化方案(PTR),推导了有限温下夸克凝聚随温度的变化关系,以及夸克凝聚时夸克质量随温度的变化关系,并研究了GMOR关系式在此条件下随温度变化的成立情况.结果表明:在零温附近,GMOR等式在误差允许范围内成立;但随着温度的升高,超过某一界限后,等式不再成立,且等式两边的偏差值越来越大.

Calculations of ■(p^6) Resonance Coupling Constants in Scalar Sector of ENJL Model

We derive the scalar resonance coupling constants of resonance chiral theory from the extended Nambu Jona-Lasinio model by using heat-kernel expansion.

Two—Point Function Reduction of Four—Point Amputated Functions and Transformations in FF and RA Basis in a Real—Time Finite Temperature NJL Model

Based on a general analysis of Green functions in the real-time thermal field theory, we have proven that the four-point amputated functions in an NJL model in the fermion bubble diagram approximation behave like usual two-point functions. We expound the thermal transformations of the matrix propagators for a scalar bound state in the FF basis and in the RA basis respectively. The resulting physical causal, advanced and retarded propagators are respectively identical to corresponding ones derived in the imaginary-time formalism, and this shows once again the complete equivalence of the two formalisms of thermal field theory on the discussed problem in the NJL model.

Chapman-Enskog Expansion and Transport Coefficients for the NJL Model

The transport equation for the Nambu-Jona-Lasinio (NJL) model isderived phenomenologically. The finite-temperature effective mass for the quarkis analysed, By means of the Chapman-Enskog method and hydrodynamic ap-proach the different transport coefficients for the NJL plasma are calculated tothe first order in the relaxation time.

开沃汽车新一代大公交NJL6113EV产品交流会圆满召开

1月9日,开沃汽车新一代大公交NJL6113EV产品交流会圆满召开。开沃汽车副总裁李江、大客营销中心执行副总经理柯有强、副总经理孟园园以及阜阳公交等11家公交公司领导汇聚一堂,现场互动热烈。会议围绕'新一代大公交NJL6113EV产品技术交流'主题展开,开沃汽车副总裁李江介绍了开沃汽车企业概况.

基于pNJL模型的三维QCD相图

基于三味Polyakov-looped Nambu-Jona-Lasinio(pNJL)模型,通过研究手征凝聚、pion凝聚和Polyakov圈之间的相互作用,研究了温度、重子化学势和同位旋化学势依赖的三维QCD相图结构。虽然pNJL模型得到的正常夸克物质相、pion超流相和Sarma相的结构以及相边界与NJL模型定性上相似,但Polyakov圈的引入大大扩展了pion超流相和Sarma相的存在区域,并导致临界点出现在较高的温度。由于有效地引入了胶子动力学的贡献,与NJL模型相比,该研究有望对三维QCD相图给出更可靠的预测。

(Pseudo) Scalar mesons in a self-consistent NJL model

In this study, we investigate the mass spectra of π and σ mesons at finite chemical potential using theself-consistent NJL model and the Fierz-transformed interaction Lagrangian. The model introduces an arbitrary parameterα to reflect the weights of the Fierz-transformed interaction channels. We show that, when α exceeds a certainthreshold value, the chiral phase transition transforms from a first-order one to a smooth crossover, which is evidentfrom the behaviors of the chiral condensates and meson masses. Additionally, at a high chemical potential, the smallerthe value of α, the higher the masses of the π and σ mesons. Moreover, the Mott and dissociation chemical potentialsincrease with the increase in α. Thus, the meson mass emerges as a valuable experimental observable for determiningthe value of α and investigating the properties of the chiral phase transition in dense QCD matter.

Properties of the phase diagram from the Nambu-Jona-Lasino model with a scalar-vector interaction

We investigated the properties of the phase diagram of high-order susceptibilities,speed of sound,and polytropic index based on an extended Nambu-Jona-Lasinio model with an eight-quark scalar-vector interaction.Non-monotonic behavior was observed in all these quantities around the phase transition boundary,which also revealed the properties of the critical point.Further,this study indicated that the chiral phase transition boundary and critical point could vary depending on the scalarvector coupling constant G_(SV).At finite densities and temperatures,the negative G_(SV)term exhibited attractive interactions,which enhanced the critical point temperature and reduced the chemical potential.The G_(SV)term also affected the properties of the high-order susceptibilities,speed of sound,and polytropic index near the critical point.The non-monotonic(peak or dip)structures of these quantities shifted to a low baryon chemical potential(and high temperature)with a negative G_(SV).G_(SV)also changed the amplitude and range of the nonmonotonic regions.Therefore,the scalar-vector interaction was useful for locating the phase boundary and critical point in QCD phase diagram by comparing the experimental data.The study of the non-monotonic behavior of high-order susceptibilities,speed of sound,and polytropic index is of great interest,and further observations related to high-order susceptibilities,speed of sound,and polytropic index being found and applied to the search for critical points in heavy-ion collisions and the study of compact stars are eagerly awaited.

维数正规化和NJL模型π介子性质

利用定义于Ｇｒａｓｓｍａｎｎ扩展空间的Ｄｉｒａｃ代数算符表象的维数正规化方案，研究Ｎａｍｂｕ－Ｊｏｎａ－Ｌａｓｉｎｉｏ（ＮＪＬ）模型中的π介子模式的性质．说明维数正规化方法可以给出ＮＪＬ模型中强子模式的解析形式和相应的符合实验的数值结果．

NJL模型中的外动量展开(英文)

建立了包括流夸克质量的SU（2）NJL模型超出平均场近似的一般框架．在这个框架内，组份夸克传播子按外动量展开，所有的费曼图可统一地得到计算．数值结果表明：在平均场近似下，流夸克质量的效应几乎看不见，只有超出平均场近似，流夸克质量的效应才能体现出来，并且NJL模型的参数更为合理．

Probing the QCD phase structure with higher order baryon numbersusceptibilities within the NJL model

Conserved charge fluctuations can be used to probe the phase structure of strongly interacting nuclear matter in relativistic heavy-ion collisions. To obtain the characteristic signatures of the conserved charge fluctuations for the quantum chromodynamics(QCD) phase transition, we study the susceptibilities of dense quark matter up to eighth order in detail, using an effective QCD-based model. We studied two cases, one with the QCD critical end point(CEP) and one without owing to an additional vector interaction term. The higher order susceptibilities display rich structures near the CEP and show sign changes as well as large fluctuations. These can provide us information about the presence and location of the CEP. Furthermore, we find that the case without the CEP also shows a similar sign change pattern, but with a relatively smaller magnitude compared with the case with the CEP. Finally, we conclude that higher order susceptibilities of conserved charge can be used to probe the QCD phase structures in heavyion collisions.

Self-consistent mean field approximation and application in three-flavor NJL model

In this study,we apply a self-consistent mean field approximation of the three-flavor Nambu–Jona-Lasinio(NJL)model and compare it with the two-flavor NJL model.The self-consistent mean field approximation introduces a new parameter,α,that cannot be fixed in advance by the mean field approach itself.Due to the lack of experimental data,the parameter,α,is undetermined.Hence,it is regarded as a free parameter and its influence on the chiral phase transition of strong interaction matter is studied based on this self-consistent mean field approximation.αaffects numerous properties of the chiral phase transitions,such as the position of the phase transition point and the order of phase transition.Additionally,increasingαwill decrease the number densities of different quarks and increase the chemical potential at which the number density of the strange quark is non-zero.Finally,we observed thatαaffects the equation of state(EOS)of the quark matter,and the sound velocity can be calculated to determine the stiffness of the EOS,which provides a good basis for studying the neutron star mass-radius relationship.

Dynamical chiral symmetry breaking in NJL Model with a strong background magnetic field and Lorentz-violating extension of the Standard Model

The Eigenstate Method has been developed to deduce the fermion propagator with a constant external magnetic field. In general, we find its result is equivalent to other methods and this new method is more convenient,especially when one evaluates the contribution from the infinitesimal imaginary term of the fermion propagator. Using the Eigenstate Method we try to discuss whether the infinitesimal imaginary frequency of the fermion propagator in a strong magnetic field and Lorentz-violating extension of the minimal SU（3）×SU（2）×SU（1） Standard Model could have a significant influence on the dynamical mass. When the imaginary term of the fermion propagator in this model is not trivial（√（α-1）eB/3） 〈 σ 〈（√（α-1）2eB/3）, this model gives a correction to the dynamical mass.When one does not consider the influence from the imaginary term（σ 〉√（α-1）2eB/3）, there is another correction from the conventional term. Under both circumstances, chiral symmetry is broken.

Do we need to use regularization for the thermal part in the NJL model?

The Nambu–Jona-Lasinio(NJL)model is one of the most useful tools for studying non-perturbative strong interactions in matter.Because it is a nonrenormalizable model,the choice of regularization is a subtle issue.In this paper,we discuss one of the general issues regarding regularization in the NJL model,which is whether we need to use regularization for the thermal part by evaluating the quark chiral condensate and thermal properties in the two-flavor NJL model.The calculations in this work include three regularization schemes that contain both gauge covariant and invariant schemes.We found that,regardless of the regularization scheme we choose,it is necessary to use regularization for the thermal part when calculating physical quantities related to the chiral condensate and to not use regularization for the thermal part when calculating physical quantities related to the grand potential.

手征化学势下的手征相变研究

利用两味道的NJL模型,研究手征化学势对手征相变临界点的影响,并考虑了均匀磁场的情况.通过对质量隙方程的求解,得出夸克的有效质量随温度等的变化情况,确定相变临界点.在研究过程中采取三维动量截断的正规化处理方式.研究表明:随着手征化学势的不断增大,临界化学势不断减小,而临界温度先增加后减小,这反映了手征化学势对手征对称性破缺的催化和逆催化效应;而磁场的增强会对手征对称性破缺起到强化作用,导致有效质量增大,临界化学势、临界手征化学势以及临界温度也会随之增大.此外,也简单地讨论了有限体积效应.

人体生理参数测量系统低功耗设计与实现

为解决无市电情况下人体生理参数的长期监测问题,采用近年新推出的光反射器NJL5501R和心电监护模拟前端芯片AD8232,利用动态电源管理、动态时钟频率控制等低功耗技术,设计了一种以STM32L152微处理器为核心的人体生理参数测量系统。实验结果表明:该系统能够完成人体血氧、心电、温度等参数的测量,具有低功耗、小体积的特点,可实现生理参数的长时间监测。

有限温度和化学势下σ、π介子的质量

利用一种重新求和方案,在Nf=2的NJL模型框架下,研究了标量σ介子、赝标量π介子的热质量.计算表明,随着温度的升高,σ介子的质量先下降,然后升高;π介子的质量一直随温度升高而增加.两种介子在温度约为0.2GeV时质量发生简并,这是手征对称性恢复的信号.π介子质量的连续变化表明相变是二阶的.化学势的提高对不同介子的质量的影响是不同的,且使手征对称性恢复提前.计算结果与其他有效模型的预言定性一致.