膨胀且旋转火球中的椭圆流
Elliptic flow in an expanding and rotating fireball
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中文总结 AI 辅助
本研究扩展火球模型至旋转情形，发现涡度对椭圆流有2-10%的贡献，椭球几何增强更显著。
中文摘要 AI 辅助
我们研究了初始轨道角动量在非对心重离子碰撞中产生椭圆流的作用。传统的膨胀火球图像首次被扩展为同时膨胀和旋转的火球，其特征是角速度。我们考虑了球形和椭球形发射几何，以及两种不同的旋转流分布，类似于整体旋转和较差旋转。虽然中快度下的横动量谱对于现实的角速度值在很大程度上对几何和流分布不敏感，但椭圆流受到各向异性膨胀和旋转的强烈影响。球形火球仅通过旋转引起的动量各向异性产生椭圆流，但其幅度在现实的角速度下仍低于观测值。相比之下，各向异性膨胀且旋转的椭球形火球在$\sqrt{s_{\rm NN}}=7.7$ GeV时表现出椭圆流相对于其非旋转对应物约$10\\%$的增强，而在$\sqrt{s_{\rm NN}}=39$ GeV时则降至$2\\%$。在我们的火球框架内，这表明涡度可以对观测到的椭圆流贡献$2-10\\%$的水平。
英文摘要
We investigate the role of initial orbital angular momentum in generating elliptic flow in off-central heavy-ion collisions. The conventional expanding fireball picture is extended for the first time to a simultaneously expanding and rotating fireball characterized by an angular velocity. Spherical and spheroidal emission geometries with two different rotating flow profiles, reminiscent of global and differential rotation, are considered for our investigation. While the transverse-momentum spectra at midrapidity are largely insensitive to the geometry and flow profile for realistic values of angular velocity, the elliptic flow is strongly affected by anisotropic expansion and rotation. A spherical fireball generates elliptic flow solely through the momentum anisotropy induced by rotation, but its magnitude remains below the observed values for realistic angular velocities. In contrast, an anisotropically expanding and rotating spheroidal fireball exhibits a $\sim 10\%$ enhancement of elliptic flow for $\sqrt{s_{\rm NN}}=7.7$ GeV, which reduces to a $2\%$ for $\sqrt{s_{\rm NN}}=39$ GeV relative to its non-rotating counterpart. Within our fireball framework, this indicates that vorticity can contribute at the $2-10\%$ level to the observed elliptic flow.
发表机构
- Indian Institute of Technology Bhilai（印度理工学院比莱分校）
机构由 AI 辅助整理，请以论文原文为准。
