强相互作用物质性质及相变研究

The Study on the phase transition and the phase structure, and the properties of strongly interacting matter at high temperature and high density, is currently one of the most interesting topics in the field of high energy physics.For the ALICE(A Large Ion Collider Experiment) experiment, hosted at CERN, the LHC will collide lead ions to recreate the conditions just after the Big Bang under laboratory conditions. Physicists hope that under these conditions, the protons and neutrons will "melt" and a state of matter called quark-gluon plasma(QGP) will be created. There are still many obsacles, such as Chiral Symmetry Breaking, Hadron structure, the phase structures and phase transitions of hadronic matter, the thermodynamic properties of QGP, lying in the theoretical studies. The phase transition process is a non-perturbative bahaviour, so some effective non-perturbative QCD models and mothods are required. We will adopt Dyson Schwinger equations in QCD, an important continuum non-perturbative QCD method, to study strongly interacting hadronic matter systems at high temperature and/or high quark density. We will focus our studies on the restoration and the broken of chiral symmetry at finite temperature and/or density, the effect of temperature and/or density on meson mass spectra, the gluon propagator and the quark-gluon vertex at finite temperature and/or density, the equation of QCD state, the phase transition, the thermodynamical properties and the transport process of QGP. The research results of these studies will improve our understanding of strong interaction and QCD, and will guide the discovery of QGP at LHC. Meanwhile these results will give some clues for the studies on the foramtion of the early universe and the evolution of the dense stellar.

高温、高密下强相互作用物质的性质及其相变研究，是当前高能物理领域最令人关注的领域之一。已经运行的欧洲核子中心的大型加速器目标之一就是在相对论重离子碰撞过程中寻找高温高密下的夸克胶子等离子体（QGP）。在强相互作用物质的理论研究中，仍存在手征对称性自发破缺、强子结构、强子物质相结构及其相变、QGP的热力学性质等问题亟待深入研究。由于相变是非微扰过程，需要发展有效的非微扰的量子场论方法。本项目着眼于高温高密下强相互作用物质的理论研究，采用非微扰、连续场论的戴逊薛温格方程方法,研究高温、高密下的手征对称性自发破缺与恢复、温度密度效应对介子谱的影响、有限密度温度下胶子传播子和夸克胶子顶点的行为、QGP的热力学性质和输运性质，探索强相互作用物质的性质及其相变过程。本项目研究结果将加深人们对强相互作用的理解和认识，为大型加速器上发现和研究QGP提供理论依据，为早期宇宙的形成过程和致密星体演化提供线索。

我们研究了EMC效应和Cronin效应对夸克胶子等离子提信号的影响，发现胶子喷注在临界能量10GeV附近存在从弱能量损失到强能量损失的跨越，这或许可作为探寻重离子碰撞过程中QGP物质的一个信号。我们研究了Z工厂中微子对的产生过程并计算了相应的散射截面,根据我们对散射截面的估计，只有Ｚ工厂的流明超过〖10〗^36 〖cm〗^(-2)∙s^(-1)时产生的中微子流明才有可能被探测到。.从强子物质到夸克胶子等离子相变过程的研究，是当前重离子碰撞和宇宙学研究的一个热门研究领域。QCD的真空凝聚和真空磁化率的变化直接反映了QCD相变过程，可以通过研究QCD真空凝聚和真空磁化率了解QCD的相变过程。我们介绍了一个模型无关的研究真空磁化率的方法，该方法在QCD求和规则中通过在QCD拉氏量中引入夸克流与外场的耦合项研究费米子对外场的响应。发现QCD真空磁化率与完全的夸克传播子对外场的线性响应紧密相关，得到了一个由夸克传播子和相应的顶点函数决定的、与模型无关的真空磁化率表达式，在DSE-BSEs的框架下计算了不同的磁化率。通过考察有限温度密度下临界终点附近的夸克数磁化率性质，研究了在临界终点附近的QCD相图，研究了三维QED模型下玻色子质量对相变的影响。