Title: Energy Correlators within Jets in Transversely Polarized Proton Proton Collisions at 200 GeV

PA: Ting Lin

Target Journal: Phys. Rev. Lett.

Abstract:  We report the first experimental measurement of one- and two-point energy–energy correlators (EECs) within jets in transversely polarized proton–proton collisions at 200 GeV. The one-point EEC correlates the jet axis with a single hadron, while the two-point EEC measures the azimuthal separation between hadron pairs in the same jet, both weighted by hadron momentum fractions. Clear spin-dependent asymmetries are observed for pi+, pi-− and pi+pi− in jets. These results provide the first direct experimental sensitivity to higher-order Mellin moments of transverse spin–dependent fragmentation functions, offering new constraints on spin–momentum correlations in hadronization. By extending energy correlator techniques to polarized hadronic collisions, this work establishes a new class of observables for spin physics. The measurements probe the transition between perturbative and nonperturbative QCD and open a promising path toward precision studies of transverse spin effects at the future Electron–Ion Collider.

Paper Draft: In preparation

Analysis Note:

   Version-1-20250819

Figure 1: Definition of one- and two-point EEC in jet

Figure 2: Asymmetry vs. phi_S - phi_{h/hh}

Figure 3: Asymmetry vs. Jet Pt

Figure 4: Asymmetry vs. theta