Speaker
Description
Transverse-momentum-dependent parton distributions (TMDs) are essential for unraveling the three-dimensional structure of hadrons, forming a core scientific component of the Electron-Ion Collider (EIC) program. Employing a novel Coulomb-gauge-fixed lattice QCD approach at physical quark masses, we reliably access transverse separations up to approximately 1 fm, corresponding to the small transverse momenta relevant for EIC measurements. In this presentation, we summarize recent lattice QCD advancements, systematically progressing from foundational calculations of the Collins-Soper (CS) kernel to detailed studies of pion and proton TMD structures. Our calculations include a first-principles determination of the nonperturbative CS kernel, crucial for describing the rapidity evolution of TMDs. Extending these methodologies, we investigate pion valence-quark TMD distributions, providing new insights into the internal transverse structure of the pion. Most significantly, our benchmark computations for proton helicity and flavor-dependent unpolarized TMDPDFs reveal similarities in transverse dependence between helicity and unpolarized distributions at moderate momentum fractions, alongside discernible flavor-dependent variations. Collectively, these lattice results pave the way, for the first time, toward direct QCD-based comparisons and serve as essential guidance for phenomenological parametrizations derived from global analyses of experimental data.
| Parallel Session (for talks only) | Structure of hadrons and nuclei |
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