标题： 重夸克输运在RHIC和LHC中 显示英文标题

标题： Heavy quark transport at RHIC and LHC

摘要： 我们计算重夸克在重离子碰撞中的演化，并展示了椭圆流$v_2$以及核修改因子$R_{AA}$在RHIC和LHC能量下的结果。 为了进行计算，我们在UrQMD（流体力学+玻尔兹曼）混合模型中实现了用于重夸克传输的朗之万方法。 作为阻力和扩散系数，我们采用共振方法来描述弹性重夸克散射，并假设底夸克从热介质中解耦的温度为$130\,\text{MeV}$。 在RHIC能量下，我们在解耦温度处采用凝聚方法来实现重夸克向D介子和B介子的强子化，并使用PYTHIA对重味电子进行次级衰变。 在LHC下，我们还采用额外的碎片化机制以考虑在更高碰撞能量下达到的更高横向动量。 显示英文摘要

摘要： We calculate the heavy quark evolution in heavy ion collisions and show results for the elliptic flow $v_2$ as well as the nuclear modification factor $R_{AA}$ at RHIC and LHC energies. For the calculation we implement a Langevin approach for the transport of heavy quarks in the UrQMD (hydrodynamics + Boltzmann) hybrid model. As drag and diffusion coefficients we use a Resonance approach for elastic heavy-quark scattering and assume a decoupling temperature of the charm quarks from the hot medium of $130\,\text{MeV}$. At RHIC energies we use a coalescence approach at the decoupling temperature for the hadronization of the heavy quarks to D-mesons and B-mesons and a sub-following decay to heavy flavor electrons using PYTHIA. At LHC we use an additional fragmentation mechanism to account for the higher transverse momenta reached at higher collision energies.