The Cu + Au collisions are expected to provide interesting new aspects in the understanding of anisotropic flow in heavy ion collisions due to asymmetric initial geometry on the transverse plane as well as due to the significant difference in number of participants in the two colliding nuclei. We calculate directed flow coefficient v 1 of thermal photons from 200 A GeV Cu + Au collisions at RHIC using a hydrodynamic model with fluctuating initial conditions and compare the results with the elliptic and triangular flow parameters. The photon v 1 ( p T ) is found to be non-zero and shows a different nature compared to the elliptic and triangular flow parameters as a function of p T . We see a negative v 1 for p T < 2 GeV/c, which becomes positive and rises slowly with larger p T (>2 GeV/c) values. The QGP radiation completely dominates the v 1...

中文翻译：

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Cu中的光子定向流## IMG ## [http://ej.iop.org/images/0954-3899/47/8/085101/toc_gab920eieqn2.gif] {$ \ mathbf {+} $} Au碰撞在相对湿度

Cu + Au碰撞有望为理解重离子碰撞中的各向异性流动提供有趣的新方面，这是由于横向平面上的初始几何形状不对称以及两个碰撞原子核中参与者数量的显着差异所致。我们使用具有波动初始条件的流体动力学模型，通过在RHIC处的200 A GeV Cu + Au碰撞计算热光子的定向流动系数v 1，并将结果与​​椭圆形和三角形流动参数进行比较。发现光子v 1（p T）为非零值，并且与椭圆和三角形流动参数相比，显示出与p T有关的不同性质。对于p T <2 GeV / c，我们看到一个负v 1，随着p T（> 2 GeV / c）的值变大，它变为正并缓慢上升。QGP辐射完全控制了v 1。