Transverse momentum broadening and energy loss of a propagating parton are dictated by the space-time profile of the jet transport coefficient $\widehat{q}$ in a dense QCD medium. The spatial gradient of $\widehat{q}$ perpendicular to the propagation direction can lead to a drift and asymmetry in parton transverse momentum distribution. Such an asymmetry depends on both the spatial position along the transverse gradient and path length of a propagating parton as shown by numerical solutions of the Boltzmann transport in the simplified form of a drift-diffusion equation. In high-energy heavy-ion collisions, this asymmetry with respect to a plane defined by the beam and trigger particle (photon, hadron, or jet) with a given orientation relative to the event plane is shown to be closely related to the transverse position of the initial jet production in full event-by-event simulations within the linear Boltzmann transport model. Such a gradient tomography can be used to localize the initial jet production position for more detailed study of jet quenching and properties of the quark-gluon plasma along a given propagation path in heavy-ion collisions.

中文翻译：

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重离子碰撞中急冷的梯度层析成像

射流传输系数的时空分布决定了横向扩散动量的扩展和能量的损失。 $\widehat{q}$在密集的QCD介质中。的空间梯度$\widehat{q}$垂直于传播方向可能导致部分横向动量分布出现漂移和不对称。这种不对称性既取决于沿横向梯度的空间位置，也取决于传播的分体的路径长度，如玻耳兹曼输运的数值解以漂移扩散方程的简化形式所示。在高能重离子碰撞中，相对于光束和触发粒子（光子，强子或射流）相对于事件平面具有给定方向的平面的这种不对称性与横向位置密切相关。线性Boltzmann传输模型中的逐项事件模拟中的初始喷气机生产量。