Exploring the 3-Dimensional Structure of Hadrons through Spin Asymmetries in High-Energy Collisions

ORAL  · Invited

Abstract

The nucleus of an atom is made up of protons and neutrons, which are a part of a broader category of particles called hadrons. However, hadrons are not a fundamental form of matter since they are composed of other particles, namely, quarks and gluons (collectively called partons), which are the elementary pieces of visible matter in our universe. These partons form a dynamical system inside of hadrons that is governed by the strong nuclear force, with quantum chromodynamics (QCD) being the theory of those interactions. A goal of nuclear physics research is to understand the internal structure of hadrons through these partons. In particular, the analysis of high-energy collisions sensitive to an intrinsic property, called spin, of hadrons and/or partons is especially useful. These observables allow us to explore the 3-dimensional (3D) motion of partons inside of hadrons. In this talk, I will discuss my research on theoretical and phenomenological QCD analyses of various high-energy collisions that give us insight into the spin and 3D structure of hadrons, especially highlighting work where undergraduate students made significant contributions.

*This work is supported by the National Science Foundation under Grant No. PHY-2308567.

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Publication: J. Cammarota, L. Gamberg, Z. B. Kang, J. A. Miller, D. Pitonyak, A. Prokudin, T. C. Rogers and N. Sato, "Origin of single transverse-spin asymmetries in high-energy collisions," Phys. Rev. D 102, 054002 (2020) [arXiv:2002.08384 [hep-ph]].
L. Gamberg, M. Malda, J. A. Miller, D. Pitonyak, A. Prokudin and N. Sato, "Updated QCD global analysis of single transverse-spin asymmetries: Extracting H ̃, and the role of the Soffer bound and lattice QCD," Phys. Rev. D 106, 034014 (2022) [arXiv:2205.00999 [hep-ph]].
B. Bauer, D. Pitonyak and C. Shay, "Numerical study of the twist-3 asymmetry ALT in single- inclusive electron-nucleon and proton-proton collisions," Phys. Rev. D 107, 014013 (2023) [arXiv:2210.14334 [hep-ph]].
D. Pitonyak, C. Cocuzza, A. Metz, A. Prokudin and N. Sato,"Number density interpretation of di- hadron fragmentation functions," Phys. Rev. Lett. 132, 011902 (2024) [arXiv:2305.11995 [hep-ph]].
C. Cocuzza, A. Metz, D. Pitonyak, A. Prokudin, N. Sato and R. Seidl, "Transversity distributions and tensor charges of the nucleon: extraction from dihadron production and their universal nature," Phys. Rev. Lett. 132, 091901 (2024) [arXiv:2306.12998 [hep-ph]].
C. Cocuzza, A. Metz, D. Pitonyak, A. Prokudin, N. Sato and R. Seidl, "First simultaneous global QCD analysis of dihadron fragmentation functions and transversity parton distribution functions," Phys. Rev. D 109, 034024 (2024) [arXiv:2308.14857 [hep-ph]].
S. Fitzgibbons, M. Malda, J. Marsh, D. Pitonyak and P. Smith, "Updated numerical study of transverse single-spin asymmetries in single-inclusive pion production from lepton-nucleon collisions," Phys. Lett. B 852, 138606 (2024) [arXiv:2401.02391 [hep-ph]].
M. Harris, J. Marsh, D. Pitonyak, A. Prokudin, J. Putnam, D. Rein and M. Schlegel, "Transverse single-spin asymmetries in γSIDIS as a direct probe of quark-gluon-quark longitudinal momentum structure," Phys. Lett. B 869, 139793 (2025) [arXiv:2505.02711 [hep-ph]].
Z. B. Kang, A. Metz, D. Pitonyak and C. Zhang, "Dihadron fragmentation framework for near-side energy-energy correlators," [arXiv:2507.17444 [hep-ph]], submitted to Physical Review Letters.

Presenters

  • Daniel Pitonyak

    • Lebanon Valley College

Authors

  • Daniel Pitonyak

    • Lebanon Valley College