Researchers have calculated energy-energy correlations (EECs) for two hadrons produced inside a jet in transversely polarized proton-proton collisions. This work is based on a model that utilizes a previous QCD analysis of dihadron fragmentation and transversity parton distribution functions. The numerical results obtained show remarkable agreement with recent measurements from the STAR experiment, which strengthens the understanding of the underlying non-perturbative mechanisms in short-range EECs.

The study also suggests that data with high jet transverse momentum show a slight preference for transversity extractions consistent with lattice QCD computations of nucleon tensor charges. Transversity is one of the three fundamental parton distribution functions (PDFs) describing the spin structure of the proton, and its precise measurement is crucial for a complete understanding of quantum chromodynamics (QCD) at low energies.

This work provides further evidence for the non-perturbative mechanism of near-side energy-energy correlators and highlights the potential of these observables to probe transverse-spin effects inside the nucleon. The ability of EECs to probe the internal structure of the proton opens new avenues for exploring the dynamics of quarks and gluons, especially concerning their angular momentum and spin, which are complex and not yet fully understood aspects of particle physics.