Helicity correlation of neighboring dihadron

The spin correlation of final-state hadrons provides a novel platform to explore the hadronization mechanism of polarized partons in unpolarized high-energy collisions. In this work, we investigate the helicity correlation of two hadrons originating from the same single parton. The production of such a dihadron system is formally described by the dihadron fragmentation function, in which the helicity correlation between the two hadrons arise from both the long-distance nonperturbative physics and the perturbative QCD evolution. Beyond the extraction of the dihadron fragmentation function, we demonstrate that it is also a sensitive observable to the longitudinal spin transfer, characterized by the single hadron fragmentation function $G_{1L}$. This intriguing connection opens up new opportunities for understanding the spin dynamics of hadronization and provides a complementary approach to corresponding studies using polarized beams and targets.