标题： 修正的特伦托初始条件及其对Cu+Au碰撞中集体流和整体极化的的影响 显示英文标题

标题： Modified Trento initial condition and its impact on collective flows and global polarization in Cu+Au collisions

摘要： 集体流系数和自旋极化是探测由相对论重离子碰撞产生的夸克-胶子等离子体（QGP）的几何形状和流速场的重要探针。利用经过修改的TRENTo初始条件与(3+1)-维粘性流体力学模型CLVisc相结合，我们研究了强子的方向流和椭圆流系数，以及不对称Cu+Au碰撞中$\Lambda$和$\bar{\Lambda}$超子的整体极化。我们将二维TRENTo模型扩展到三维空间，并发现QGP火球相对于纵向方向的初始倾斜几何形状导致了方向流从正到负伪快度值随着伪快度的增加而减小，椭圆流在前向和后向伪快度处增强，以及超子的横向动量上整体极化的非单调依赖关系。初始纵向流速梯度进一步增强了方向流和整体极化的数值。我们的模型计算首次对Cu+Au碰撞中电荷强子的方向流在快速度、横向动量和中心性上的依赖关系提供了令人满意描述，并提出这种不对称重离子碰撞比对称的Au+Au碰撞创造了更好的环境来研究QGP的初始倾斜几何形状和纵向流场。 显示英文摘要

摘要： Collective flow coefficients and spin polarization are valuable probes of the geometry and flow velocity field of the quark-gluon plasma (QGP) produced in relativistic heavy-ion collisions. Using a modified TRENTo initial condition coupled to a (3+1)-dimensional (D) viscous hydrodynamic model CLVisc, we study the directed flow and elliptic flow coefficients of hadrons, together with the global polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons in asymmetric Cu+Au collisions. We extend the 2D TRENTo model to the 3D space, and find that the initial tilted geometry of the QGP fireball with respect to the longitudinal direction leads to a decrease of directed flow from positive to negative values with increasing pseudorapidity, an enhancement of elliptic flow at forward and backward pseudorapidities, and a non-monotonic dependence of global polarization on the transverse momentum of hyperons. The initial longitudinal flow velocity gradient further enhances the values of directed flow and global polarization. Our model calculation provides a satisfactory description of the rapidity, transverse momentum, and centrality dependences of the directed flow of charged hadrons in Cu+Au collisions for the first time, and proposes that such asymmetric heavy-ion collisions create a better environment for studying the initial tilted geometry and longitudinal flow field of the QGP than symmetric Au+Au collisions do.