Energy Correlators Within Jets in Transversely Polarized Proton-Proton Collisions at $\sqrt{s} = 200$ GeV

We report the first measurement of one- and two-point energy correlators within jets in transversely polarized proton–proton collisions at $\sqrt{s}=200$ GeV, using the STAR detector at RHIC. These observables quantify the energy-weighted angular distribution of single hadrons and hadron pairs within jets, respectively. Sizable spin-dependent asymmetries are observed for $\pi^+$, $\pi^-$, and $\pi^+\pi^-$, revealing the onset of nonperturbative dynamics at specific angular scales. By projecting the fragmentation dynamics onto Mellin moments, these measurements provide direct sensitivity to the nucleon’s transversity while mitigating uncertainties from nonperturbative fragmentation functions. These results establish energy correlators as a new precision probe of nucleon structure and open a promising avenue for three-dimensional nucleon tomography at the future Electron–Ion Collider.