AI 中文总结
研究重离子碰撞中热双轻子极化，通过夸克 - 反夸克湮灭过程，利用外场下修正夸克传播子推导电磁谱函数，确定相关系数，发现涡度和磁场对双轻子极化不变质量谱有不同影响，其可作为碰撞中涡度和磁场的灵敏探针。
AI 中文摘要
双轻子（虚光子）极化由各向异性系数$\lambda_{\theta}$、$\lambda_{\phi}$和$\lambda_{\theta\phi}$表征，预计受涡度和磁场影响。本工作通过夸克 - 反夸克湮灭过程$q\bar{q} \to \gamma^* \to l^+l^-$研究夸克 - 胶子等离子体中的热双轻子产生。虚光子极化可由夸克的自旋极化及其在介质中动量分布的各向异性诱导。通过采用外场下修正的夸克传播子，推导热介质中的电磁谱函数。基于谱函数的自旋投影分解，确定虚光子的自旋密度矩阵元及发射双轻子的各向异性系数。由于涡度和磁场对夸克传播子的不同影响，双轻子极化的不变质量谱呈现特征差异。此外，研究揭示双轻子极化信号对不同强度外场的响应，表明双轻子极化是相对论重离子碰撞中涡度和磁场的补充且灵敏的探针。
英文摘要
Dilepton (Virtual photon) polarization is characterized by anisotropic coefficients $λ_θ$, $λ_ϕ$, and $λ_{θϕ}$, which are expected to be influenced by vorticity and magnetic fields. This work investigates thermal dilepton production in a quark-gluon plasma via the quark-antiquark annihilation process $q\bar{q} \to γ^* \to l^+l^-$. Virtual photon polarization can be induced by both the spin polarization of quarks and the anisotropy of their momentum distribution in the medium. By employing the modified quark propagator under an external field, we derive the electromagnetic spectral function in a hot medium. Based on the spin-projection decomposition of the spectral function, the spin density matrix elements of the virtual photon and the anisotropy coefficients for the emitted dileptons are determined. Due to the distinct effects of vorticity and magnetic fields on the quark propagator, the resulting invariant mass spectra of dilepton polarization exhibit characteristic differences. Furthermore, our study reveals the response of dilepton polarization signals to external fields of varying strengths, suggesting dilepton polarization as a complementary and sensitive probe for both vorticity and magnetic fields in relativistic heavy-ion collisions.
Comments20 pages, 8 figures
