Energy dependence of longitudinal flow decorrelation from STAR

Measurements of longitudinal flow decorrelations for charged particles are presented in the pseudorapidity range $|\eta| < 1$ using a reference detector at 2.1 $< |\eta_{\mathrm{ref}}| <$ 5.1 Au+Au collisions $\sqrt{s_{NN}}$ = 27 GeV by STAR. The decorrelation $v_2$ shows strong centrality dependence, while weak dependence $v_3$. Results compared with results 200 as function $\eta$ scaled beam-rapidity, i.e. $\eta/y_{beam}$. No energy is observed decorrelation, but clear $v_3$ decorrelation. These provide new insights into structure initial-state geometry heavy-ion collisions.