Azimuthally-Differential Pion Femtoscopy in Cu plus Au and Au plus Au Collisions at root S-NN=200 GeV in the STAR Experiment

摘要

Anisotropic flow is sensitive to the properties of the systems created in heavy-ion collisions. Azimuthally-sensitive femtoscopy with respect to the first-order event plane is coupled with the directed flow, and probes the space-time structure of the particle-emitting source. The knowledge of the source tilt can give a helpful experimental handle on the origin of the anisotropic flow. In addition, the tilt angle dependence on different collision systems at the same energy can provide constraints on theoretical models. In the experiment, this information can be extracted by measuring pion femtoscopic radii as a function of the pair emission angle with respect to the first-order event plane. In this work, we present comparisons between the results of the radius oscillations of the pion-emitting sources at root S-NN = 200 GeV in symmetric (Au + Au) and asymmetric (Cu + Au) collisions measured with the STAR experiment, and those estimated in the UrQMD model.