从流夸克质量到组分夸克质量的动力学过渡的研究

在彩虹近似下用Dyson Schwinger 方程研究了禁闭夸克的传播子, 得到了夸克动力学质量随动量变化的关系, 即得到了从流夸克质量到组分夸克质量的动力学过渡.     

中子星内部非奇异-奇异夸克物质的相变

研究了中子星内部从两味夸克物质到三味夸克物质的相变过程。发现这个过程的时标短至10^-7s,并且在相变中奇异夸克所参加的半轻子过程是中微子能量损失的主要过程。这样,1.4M_⊙质量的中子星内部的非奇异-奇异夸克物质相变会有几个10⁵¹erg的能量以中微子形式发射出去,这将表现为一种中微子爆现象。     

色味锁夸克物质与夸克星

讨论了零温、强磁场下基于准粒子模型的奇异夸克物质、色味锁夸克物质的热力学性质.结果表明色味锁夸克物质比奇异夸克物质更稳定,压强会随着色味锁态能隙常数的增大而增加.并且发现强磁场下磁星的最大质量会随着色味锁夸克物质的能隙常数的增加而增加,磁星的潮汐形变率会随着能隙常数的增加而增加,磁星最大质量的中心密度会随着能隙常数的增加而降低.结果还说明考虑色味锁态得到的磁星质量半径关系可以满足最近实验观测PSR J0740+6620, PSR J0030+0451,和HESS J1731-347所给出的质量半径约束.     

重夸克偶素质量谱的相对论夸克模型研究（已撤稿）

使用量子场论中准势途径的相对论夸克模型,计算了重夸克偶素的质量谱.所采用的同味正反夸克间的有效相互作用包括通常的直接单胶子交换、单胶子湮没及具有相对论修正的标量和矢量线性禁闭的混合.得到了与实验上肯定的数据符合较好的拟合计算结果，并讨论了湮没项和相对论修正各项对能谱超精细分裂的作用. 关键词： 重夸克偶素 质量谱 相对论修正 湮没势     

关于奇异夸克物质的性质

基于以前的工作,导出了新的奇异夸克质量公式,并用于研究奇异夸克物质的性质,得到与MIT袋模型类似的结果.而且发现,新公式导致与以前有所不同的结果,即声速随能量密度的增加而趋向于极端相对论情况的速度减慢.     

热力学自洽的质量密度依赖夸克模型与混合星

用热力学自洽的质量密度依赖夸克模型描述夸克物质研究了混合星的基本性质, 计算了混合星内粒子分布、状态方程和对应的质量-半径关系. 结果表明, 质量密度依赖夸克模型中由热力学自洽处理所引起的压强附加项使整个混合星的状态方程变软, 相变始末点推迟, 从而使混合星的最大质量由无附加项时的大于2.4M_⊙, 变到小于1.8M_⊙, 相应的半径R由大于15km变到小于12.0km. 与NJL模型类似, 该模型更适合描述大质量的混合星.     

奇异夸克物质的夸克质量密度温度相关模型(英文)

在夸克质量密度相关模型处理奇异夸克物质滴时 ,会发现其半径随温度增加而变小 .为克服这一困难 ,我们通过使口袋常数 B温度参数化 ,引入了夸克质量密度温度相关模型 .在这一模型中 ,B=B0 [1 - a(T/Tc) +b(T/Tc) 2 ],文章中讨论了参数 a,b的取法. It is found that the radius for a stable strangelet is a decreasing function of temperature in quark mass density- dependent model. To overcome this difficulty, we extend this model to quark mass density- and temperature- dependent model in which the vacuum energy density at zero baryon density limit B depends on temperature. An ansatz B=B 0[1-a(T/T c )+b(T/T c ) 2] is introduced and the regions for the best choice of the parameters are studied.     

夸克与反夸克不对称的奇异海对温伯格角的修正

NuTeV实验组报道了用中微子–核子深度非弹散射方法测量到的温伯格角(Weinbergangle)sin2θw的值,并且发现这个值与标准模型的预言值相差3个标准偏差.在这篇文章中,推导了考虑核子海中s夸克与反夸克不对称时Paschos-Wolfenstein关系,分别用两种不同类型的波函数计算了在光锥介子–重子波动模型(light-conemeson-baryonfluctuationmodel)下核子海中s夸克与反夸克分布的情况且得出相近的结果.并且发现,由核子海中奇异夸克反夸克不对称所引起的修正能够降低NuTeV的测量的温伯格角的值和标准模型的预言值之间偏差的30%—80%.     

核子中奇异夸克分布不对称性与轻味夸克碎裂效应

核子中奇异－反奇异夸克分布的不对称性是核子结构研究中的重要非微扰效应, 然而至今未被实验所直接检验.为了探讨测量这种奇异分布不对称性的有效方法,考察了轻味夸克碎裂效应对测量奇异分布不对称性的影响.建议通过直接测量高能中微子和反中微子的带电流深度非弹散射中的带电和中性D介子的微分截面来测量奇异分布的不对称性.这种方法能够使奇异分布不对称性与轻味夸克碎裂的效应相分离.     

有限温度奇异夸克物质

本文简要介绍了近年来有限温度下奇异夸克物质的研究,包括早期宇宙中大块奇异夸克物质的研究;基于ＭＩＴ袋模型的ｓｔｒａｎｇｅｌｅｔ研究,以及运用质量密度相关模型对奇异夸克物质的研究,最后简略评述了关于奇异夸克物质性质的近期研究进展     

The mass effect of the quark phase transition in supernova core

Constituent quark mass model is adopted as a tentative one to study the phase transition between two-flavour quark matter and more stable three-flavour quark matter in the core of supernovae. The result shows that the transition has a significant influence on the increasing of the core temperature, the neutrino abundance and the neutrino energies, which contributes to the enhancement of the successful probability of supernova explosion. However, the equilibrium values of these parameters （except the temperature） from the constituent quark mass model in this work are slightly bigger than those obtained from the other model. And we find that the constituent quark mass model is also applicable to describing the transition in the supernova core.     

Effect of current quark masses on quark phase transitions in supernovae

The current quark mass model is adopted to study the phase transition of two-flavor quark matter to more stable three-flavor quark matter in the whole core of a supernova. It shows that the timescale of the process is shorter than 10-8 seconds, thatthe u- and d-quark masses can be neglected completely in this model, and that the temperature and the total neutrino energies in the core after the conversion increase nearly by 40% and 20% on the average compared with former results, respectively. The last result can further enhance the probability of success for a supernova explosion significantly.     

Effect of current quark masses on quark phase transitions in supernovae

The current quark mass model is adopted to study the phase transition of two-flavor quark matter to more stable three-flavor quark matter in the whole core of a supernova. It shows that the timescale of the process is shorter than 10^－8 seconds, that the u- and d-quark masses can be neglected completely in this model, and that the temperature and the total neutrino energies in the core after the conversion increase nearly by 40% and 20% on the average compared with former results, respectively. The last result can further enhance the probability of success for a supernova explosion significantly.     

Effect of Quark Strong Interaction in Phase Transition on Supernova Explosion

The effect of quark interactions perturbatively to order αc on the conversion, from quark matter to strange quark matter, is studied systematically based on a recent set of current quark masses. The process has a significant effect on increasing the core temperature, the neutrino abundance and the neutrino energies even if there is no quark interaction. Furthermore, with the switch of the strong interaction among quarks, these quantities will increase respectively to some further extents with αc increase. Taking αc = 0.47 as an example, the temperature, the neutrino abundance and the total neutrino energies are further raised by about 10%, 7%, and 20% respectively, which is weakly dependent on the initial temperature. Combining the effect of the current quark mass and the effect of the quark strong interaction, the results of the conversions will greatly enhance the probability of success for a supernova explosion and deeply influence the dynamics of the supernova evolution.     

Core collapse supernovae in the QCD phase diagram

We compare two classes of hybrid equations of state with a hadron-to-quark matter phase transition in their application to core collapse supernova simulations. The first one uses the quark bag model and describes the transition to three-flavor quark matter at low critical densities. The second one employs a Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model with parameters describing a phase transition to two-flavor quark matter at higher critical densities. These models possess a distinctly different temperature dependence of their transition densities which turns out to be crucial for the possible appearance of quark matter in supernova cores. During the early post-bounce accretion phase quark matter is found only if the phase transition takes place at sufficiently low densities as in the study based on the bag model. The increase critical density with increasing temperature, as obtained for our PNJL parametrization, prevents the formation of quark matter. The further evolution of the core collapse supernova as obtained applying the quark bag model leads to a structural reconfiguration of the central protoneutron star where, in addition to a massive pure quark matter core, a strong hydrodynamic shock wave forms and a second neutrino burst is released during the shock propagation across the neutrinospheres. We discuss the severe constraints in the freedom of choice of quark matter models and their parametrization due to the recently observed 2M _?? pulsar and their implications for further studies of core collapse supernovae in the QCD phase diagram.     

质量密度相关模型研究CFL奇异夸克物质性质

在质量--密度相关模型下研究了CFL奇异夸克物质, 并将结果与传统的袋模型结果进行比较. 两个模型均表明, 在合理的参数范围内, CFL相比正常核物质更稳定. 然而, 低密度时声速的行为完全相反, 这使得CFL夸克星的最大质量在质量-密度相关模型下比袋模型大.     

恒星演化和超生爆发理论中某些重要问题的核物理问题

首先,在第1节中我们依次介绍了各种不同质量的恒星演化进程中各个主要热核燃烧的点火条件,致密物质中自由电子系统的简并性对星体热核燃烧的主导作用以及爆炸性核燃烧条件。其次,在第2节中我们讨论了导致恒星核心不稳定坍缩的物理因素和条件。此后,在本第3节中我们评述了Ia型超新星爆发理论尚在急论中的核物理和固体物理的问题。在第4节中我们评述了Ⅱ型（以及Ib型）超新星爆发理论中的严重困难,并且介绍了我们（南京大学研究小组）就超新星中微子延缓爆发机制的关键问题（强大的中微子暴如何产生？）的物理机制提出的具体过程：这中微子暴的强大中微子流量是从刚刚坍缩的高温高密核心通过核物质－－（u,d）夸克系统－－（u,d,s)系统的相变过程在不到1微秒的时间内很快地产生出来的。而且,这个过程导致核心区域的负熵梯度,引起核心区域大规模对流,它将这强大的中微子流量很快地向外输送到中微子球的表面。在第5节中本还介绍了我们就超新星核心高密条件下电荷屏蔽对电子俘获过程的影响所作的探讨研究以及讨论了它对超新星坍缩核心质量（它对超新星瞬时爆发机制成功与否起着关键作用）的可能影响。     

Deconfinement Phase Transition Including Perturbative QCD Corrections in （Proto）neutron Star Matter

Deconlinement phase transition and neutrino trapping in （proto）neutron star matter are investigated in a chiral hadronic model （also referred to as the FST model） for the hadronic phase （HP） and in the color-flavor-locked （CFL） quark model for the deconlined quark phase. We include a perturbative QCD correction parameter αs in the CFL quark matter equation of states. It is shown that the CFL quark core with K^0 condensation forms in neutron star matter with the large value of αs. If the small value of αs is taken, hyperons suppress the CFL quark phase and the liP is dominant in the high-density region of （proto）neutron star matter. Neutrino trapping makes the fraction of the CFL quark matter decrease compared with those without neutrino trapping. Moreover, increasing the QCD correction parameter as or decreasing the bag constant B and the strange quark mass ms can make the fraction of the CFL quark matter increase, simultaneously, the fraction of neutrino in protoneutron star matter increases, too. The maximum masses and the corresponding radii of （proto）neutron stars are not sensitive to the QCD correction parameter αs.     

Nuclear matter at high density: Phase transitions,multiquark states,and supernova outbursts

Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partialwave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of P matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determines the natural scale of the density for a possible phase transition into theMQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernovamodels. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.