Energy dependence of rescattering effect on vector mesons spin alignment at RHIC

Spin alignment of vector mesons in heavy-ion collisions provides a novel probe of quark polarization and hadronization mechanism in quark-gluon plasma. Hadronic rescattering may affect the measured spin alignment of vector mesons due to non-uniform rescattering probability in non-central heavy-ion collisions. Using the UrQMD model, we systematically investigated the hadronic rescattering effect on the measurement of ρ 00 , the spin alignment parameter, for K ⁎0 , ϕ , and ρ 0 mesons in Au+Au collisions at s NN = 7.7 - 200 GeV. Our results reveal that the observed Δ ρ 00 = ρ 00 − 1 / 3 values are largely consistent with zero for ϕ , while showing significantly negative (positive) deviations for K ⁎0 and ρ 0 with respect to the reaction (production) plane. Quantitatively, the maximum deviation reaches − 0.0063 (0.0264) for K ⁎0 and − 0.0124 (0.0416) for ρ 0 with respect to the reaction (production) plane. Notably, the deviations in ρ 00 for both K ⁎0 and ρ 0 increase monotonically with increasing collision energy. These findings underscore the critical necessity of accounting for rescattering effects when interpreting spin alignment measurements of short-lived vector mesons in heavy-ion collisions.