System scan of the multiplicity correlation between forward and backward rapidities in relativistic heavy-ion collisions using a multi-phase transport model

A systematic study on forward–backward(FB)multiplicity correlations from large systems to small ones through a multi-phase transport model(AMPT)has been performed and the phenomenon that correlation strength increases with centrality can be explained by taking the distribution of events as the superposition of a series of Gaussian distributions.It is also found that correlations in the η−ϕ plane can imply the shape of the event.Furthermore,long-range correlations originate from the fluctuations associated with the source information.FB correlations allow us to decouple long-range correlations from short-range correlations,and may provide a chance to investigate the α-clustering structure in initial colliding light nuclei as well.It seems the tetrahedron ^(16)O+^(16)O collision gives a more uniform and symmetrical fireball,that emits the final particles more isotropically or independently in the longitudinal direction,indicating that the forward-backward multiplicity correlation could be used to identify the pattern of α-clustered ^(16)O in future experiments.