Transverse momentum dependent decorrelation in Pb–Pb collisions at LHC

Based on A Multi-Phase Transport (AMPT) model simulations, the transverse momentum dependent decorrelation has been studied in Pb-Pb collisions at $\sqrt{s_{NN}}$= 2.76 and 5.02 TeV, respectively. It has been found that the mix-order factorization ratio $r_{m, n}$ value deviates significantly from unity in noncentral collisions. Such effect becomes stronger with an increase in the $p_{T}$ difference $p_{T}^{a}-p_{T}^{b}$. These decorrelations are not only between the same order harmonic but also between the different order harmonic, which as a result of the initial fluctuations appear between the different phase spaces. It has also been found that the correlations involving higher powers of the flow vector yield stronger decorrelation, $r_{m|n;3}<r_{m|n;2}<r_{m|n;1}~(m=2,3; n=2,3,4,5)$, except for the weighted factorization ratio $r_{3|4;k}$. The breaking phenomenon of these factorization ratios indicated that it provides a possible observation for studying the initial fluctuation properties of heavy-ion collisions.