中国物理学会高能物理分会第十三届全国粒子物理学术会议（2021）

Anisotropic flow phenomena is a key probe of the existence of Quark-Gluon Plasma. The second and the third order anisotropic flow, V2 and V3 , are mostly determined by the corresponding initial spatial anisotropy coefficients, e2 and e3 , in the initial density distribution. In addition to their dependence on the same order initial anisotropy coefcient, higher order anisotropic ow, Vn (n > 3), can also have a signicant contribution from lower order initial anisotropy coefcients, which leads to mode-coupling effects. Several new observable associated with correlations between anisotropic flow harmonics, i.e, symmetric cumulants are developed, which are expected to be sensitive to the initial fluctuations and transport properties of the created matter in heavy ion collisions. Small collision systems, such as proton-proton and proton-lead, are usually used to provide the reference data for collisions of heavy nuclei. However, inspection of high multiplicity pp interactions revealed surprising features, usually attributed to collective effects in heavy-ion collisions. Thus, one of the main goals of this work is to understand these unexpected observations. We will show in this talk the recent developments of nonlinear flow response and symmetric cumulants.