改进的PNJL模型下QCD的相图

Polyakov-Nambu-Jona-Lasinio（PNJL）模型是研究强相互作用物质性质的使用最为广泛的有效模型之一。在PNJL模型的基础上考虑了手征凝聚和Polyakov圈之间的纠缠作用,并且引入了化学势修正的Polyakov有效势,由此得到了化学势依赖的entangled PNJL（μEPNJL）模型。在平均场框架下的计算结果表明:相较于原始的PNJL模型,由μEPNJL模型计算得到的临界点（CEP）朝着温度更高、化学势更小处移动,并且手征对称性恢复相变和退禁闭相变在较大的化学势范围内都重合得很好。通过与STAR合作组在相对论重离子对撞机（RHIC）上进行的净质子数分布的测量结果相比,可以发现,通过适当的参数调节,由μEPNJL模型计算得到的CEP更加靠近实验预言的CEP可能存在的区域。Polyakov-Nambu-Jona-Lasinio (PNJL) model is one of the most popular effective quark models to investigate the properties of strongly interacting matter. Based on the PNJL model, we consider the entanglement interactions between the chiral condensate and Polyakov-loop, as well as the chemical potential modification of Polyakov-loop potential simultaneously, which is named μEPNJL model. Compared with the original PNJL model, the calculations in the mean field approximation show that the critical end point (CEP) given in the μEPNJL model moves towards higher temperature and smaller chemical potential in the T-μ phase diagram. Besides, the chiral symmetry restoration and deconfinement phase transition coincide well in a wide range of chemical potential. Comparing our calculations with the measurement of the moments of net-proton multiplicity distributions at Relativistic Heavy-Ion Collider (RHIC) by STAR Collaboration, we find that the CEP given by μEPNJL model can be closer to the range predicted by the experiment through appropriate parameter adjustment.     

量子色动力学在有限温度密度区间的相结构(英文)

本文综述量子色动力学在有限温度密度区间的相结构,包括高密条件下的色超导态和在高温条件下相对论重离子碰撞实验中产生的强耦合夸克-胶子等离子体。我们简要地介绍在相对论重离子碰撞实验中发现强耦合夸克-胶子等离子体的历史,并且讨论用体粘滞系数与熵的比值确定QCD临界点的可能性。对于在高密区域的相结构,我们着重讨论错位配对情况下的非标准色超导态,解释无能隙色超导态的色磁不稳定性、Sarma不稳定性和Higgs不稳定性.     

量子色动力学在有限温度密度区间的相结构

本文综述量子色动力学在有限温度密度区间的相结构,包括高密条件下的色超导态和在高温条件下相对论重离子碰撞实验中产生的强耦合夸克-胶子等离子体。我们简要地介绍在相对论重离子碰撞实验中发现强耦合夸克-胶子等离子体的历史,并且讨论用体粘滞系数与熵的比值确定QCD临界点的可能性。对于在高密区域的相结构,我们着重讨论错位配对情况下的非标准色超导态,解释无能隙色超导态的色磁不稳定性、Sarma不稳定性和Higgs不稳定性.     

重论超子化与芯冠转变对中子星潮汐形变的效应

从引力波数据提取的中子星潮汐形变为包含核态方程信息的中子星结构提供了新颖的探针。利用相对论平均场密度依赖的参数,在这篇QCS2023专刊文章中,重点关注中子星的超子组份与芯冠转变对潮汐形变的作用。鉴于两者都存在大的不确定度,阐明了变化参数化模型所许可的芯冠转变密度与超子组份两者都可以对中子星潮汐形变有显著的效应。这些结果对进一步的实验与理论工作具有一定的启示作用。

     

夸克物质对称能与夸克星潮汐形变的研究

近十年的研究表明,夸克物质对称能对夸克物质的状态方程有重要影响。在本研究中,通过采用等效质量模型并在夸克质量标度中引入同位旋依赖项来研究夸克物质的稳定窗口。研究结果表明,足够大的同位旋强度依赖参数$ C_I $可以显著地增大奇异夸克物质的稳定窗口,从而使计算结果可以同时满足天文观测数据PSR J1614-2230具有$ 1.928 pm 0.017 $倍太阳质量和双中子星并合事件GW170817中得到的潮汐形变$ 70 leqslant varLambda_{1.4} leqslant 580 $的约束。与奇异夸克物质的情况相反,u-d夸克物质的稳定窗口会随着同位旋强度依赖参数的增大而减小,从而使u-d夸克星无法支持相应的天文观测数据。最后,发现奇异夸克物质的对称能远大于u-d夸克物质的对称能,并且夸克间的单胶子交换相互作用会导致奇异夸克物质的对称能变软。     

Cumulants in the 3-dimensional Ising,O（2） and O（4） spin models

Based on the universal properties of a critical point in different systems and that the QCD phase transitions fall into the same universality classes as the 3-dimensional Ising, O（2） or O（4） spin models, the critical behavior of cumulants and higher cumulant ratios of the order parameter from the three kinds of spin models is studied. We found that all higher cumulant ratios change dramatically the sign near the critical temperature. The qualitative critical behavior of the same order cumulant ratio is consistent in these three models.     

相变与临界乳光现象

分别采用白炽聚光灯和氦氖激光器照射,观察六氟化硫在临界点附近的临界乳光现象.     

Critical Behavior of Liquid 3He

We investigate the liquid–gas second-order phase transition in liquid ³He using the variational calculations based on the cluster expansion of the energy functional. We also compute the critical point exponents of liquid ³He that are in agreement with experimental data.     

A contact process with a single inhomogeneous site

The one-dimensional basic contact process is a Markov process for which particles give birth on vacant nearest neighbor sites at rate >0 and particles die at rate one. We introduce a one-dimensional contact process with a single inhomogeneous site: the evolution is as above except that a particle located at the origin does not die. Let _c be the critical value of the basic contact process. We show that for _c the upper invariant measures of the inhomogeneous contact process and the basic contact process coincide except at a finite number of sites. The behavior at = _c is much more intersting: the upper invariant measure of the inhomogeneous contact process concentrates on configurations with infinitely many particles, while it is known that the critical basic contact process dies out. So a single inhomogeneity may provoke a perturbation unbounded in space. As a byproduct of our analysis we prove that the connectivity probabilities of the critical basic contact process are not summable. We also give a biological interpretation of this model.     

相互作用玻色子模型中振转过渡区的特征研究

详细研究了相互作用玻色子模型中U(5)振动极限到SU(3)转动极限的相变行为.通过对能谱和E2跃迁强度等的分析,说明了在临界点的核具有最大的非刚性. Transitional patterns from the U(5) vibrational limit to the SU(3) rotational limit in the interacting Boson model are studied in detail. The transitional behavior of low-lying energy levels, isomer shifts, E2 transition rates, and some other related quantities across the entire region are investigated. The results show that nuclei in the critical region are most non-rigid.     

Shape evolution and test of the critical-point symmetry X(5) in 176Os

The lifetimes of excited states in the yrast band of 176Os have been measured up to I = 20h level using the Doppler shift attenuation method. The high-spin states of 176Os were populated via fusion evaporation reaction 152Sm(28Si,4n)176Os at a beam energy of 140 MeV. The results support an X(5) structure for 176Os at low spin. This structure disappears at high spin and shows a symmetry rotor character. The shape change of 176Os is similar to that of 178Os.     

Critical behaviour of Sn2P2S6 and Sn2P2(Se0.28S0.72)6 crystals under high hydrostatic pressures

Basing on the temperature dependences of optical birefringence for Sn₂P₂S₆ and Sn₂P₂(Se_0.28S_0.72)₆ crystals subjected to hydrostatic pressures, we prove unambiguously that Sn₂P₂S₆ reveals a tricritical point on its (p, T)-phase diagram with the coordinates (p, T) = (4.3 kbar, 259 K), so that the second-order phase transition transforms into the first-order one whenever the pressure increases above 4.3 kbar. We also find that increasing hydrostatic pressure applied to Sn₂P₂(Se_0.28S_0.72)₆ leads to the change in the phase transition character from tricritical to first order. Further increase in the pressure up to ~2.5 kbar imposes splitting of the first-order paraelectric-to-ferroelectric phase transition into two phase transitions, a second-order paraelectric-to-incommensurate one and a first-order incommensurate-to-ferroelectric transition.     

Critical Mass of Gauge Boson in Rainbow QED3

In three-dimensional quantum electrodynamics (QED₃) with a massive gauge boson, we investigate the coupled Dyson-Schwinger equations for the fermion and photon propagators in the rainbow approximation, and obtain the critical gauge boson mass for various numbers of the fermion flavors. A comparison with the previous results is presented.