Rapidity distributions of net protons from AGS to LHC energy regions

Taking the conservation of baryon number into account in a non-uniform flow model, the rapidity distribution of the net protons at the LHC is predicted. The energy dependence of the rapidity distribution, baryon stopping and collective flow from BNL/AGS to CERN/LHC are systematically investigated.     

Estimation of the chiral magnetic effect considering the magnetic field response of the QGP medium

The magnetic field plays a major role in searching for the chiral magnetic effect in relativistic heavy-ion collisions. If the lifetime of the magnetic field is too short, as predicted by simulations of the field in vacuum, the chiral magnetic effect will be largely suppressed. However, the lifetime of the magnetic field will become longer when the QGP medium response is considered. We give an estimate of the effect, especially considering the magnetic field response of the QGP medium, and compare it with the experimental results for the background-subtracted correlator H at RHIC and LHC energies. The results show that our method explains the experimental results better at the top RHIC energy than at the LHC energy.     

相对论重离子碰撞中背景磁场的计算与分析

通过洛伦兹变换推导了相对论匀速运动点电荷磁场公式.在此基础上得到了相对论重离子碰撞中背景磁场的计算公式,并考虑原子核在纵向的厚度.对RHIC能区Au-Au碰撞和LHC能区Pb-Pb碰撞所产生的磁场进行了数值计算,着重讨论了原点磁场的能量依赖性质并给出了直观的定性解释.     

相对论重离子碰撞手征电荷分离效应的研究

相对论重离子碰撞的拓扑荷作用破坏作用平面两侧不同手征性的夸克数目的平衡,从而引起P和CP破坏特征。本工作主要分析RHIC和LHC能区的手征电荷分离作用,分析手征电荷分离随碰撞中心度、碰撞能量和核屏蔽等依赖关系。并未发现手征电荷分离效应与碰撞能量大小有非常紧密的依赖关系,但发现核屏蔽效应对手征电荷分离有重要的影响,与不考虑屏蔽效应相比,考虑屏蔽效应会使手征分离效应明显压低,由于屏蔽效应出现,使得a₊₊（a_--）的分布与a_+-（a_-+）分布并不对称。并且还发现手征分离效应主要发生在碰撞参量较大的周边碰撞,越接近中心碰撞,手征分离效应几乎可以忽略。The topological charge interactions in relativistic heavy ion collisions cause quark chirality imbalance, resulting in charge separation under the strong magnetic field and local P and CP violation. In this paper, the chiral charge separation at RHIC and LHC energies is systematically analyzed as functions of the collision centrality, the collision energy and the nuclear shielding factor. It is found that there is not a very close dependence of the chiral charge separation effect on the collision energies, but that has an important dependence on nuclear shielding factor. Compared with the non-shielding effect, the shielding effect can reduce the chiral separation effect obviously. Due to the shielding effect, the distribution of a₊₊(a_--) and the distribution of a_+-(a_-+) are asymmetric. One also finds that chiral separation effect, which is almost negligible when more close to the central collision, occurs mainly in the peripheral collision for larger impact parameter.     

高效催化氧还原及氧析出反应的掺杂石墨炔的设计与理论计算

在清洁和可再生能源的转化过程中, 氧还原反应和氧析出反应需要高效的电催化剂以克服其动力学限制. 本文设计了一系列掺杂杂原子的无金属石墨二炔, 以促进上述两类关键化学反应.为了评估电催化性能, 利用密度泛函理论研究了反应路径和吉布斯自由能变化. 计算结果表明, 掺杂剂可以优化中间体的吸附, 降低反应的过电位. 本文还得到了将催化剂性质与催化剂结构相关联的内在描述符, 该描述符可以加速开发和筛选新型电催化剂. 研究结果可为清洁能源技术(如燃料电池、 金属空气电池和电解水等)中碳基催化剂的设计提供指导.