PHENIX Spin Physics Overview


  • Dillon S. Fitzgerald University of Michigan



PHENIX, spin physics, spin asymmetries, longitudinal double-spin asymmetries, transverse single-spin asymmetries, direct photons, heavy flavor, charged pions, neutral mesons, jets, neutrons, gluon helicity, trigluon correlators


Understanding the spin structure of the proton is of large interest to the nuclear physics community and it is one of the main goals of the spin physics program at the Relativistic Heavy Ion Collider (RHIC). Measurements from data taken by the PHENIX detector with transverse (p ↑ + p, p ↑ + Al, p ↑ + Au) and longitudinal (⃗p + ⃗p) proton polarization play an important role in this, in particular due to the leading order access to gluons in polarized protons. This is a crucially important counterpart to measurements made in lepton-hadron scattering experiments where gluons are not accessible at leading order. Transverse spin asymmetries provide insight into initial and final-state spinmomentum and spin-spin parton-hadron correlations, while longitudinal spin asymmetries provide access to parton polarization. A number of important recent PHENIX results and ongoing analyses will be presented, along with a discussion of how these measurements contribute to our understanding of proton spin structure.


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U. A. Acharya et al., Measurement of charged pion double spin asymmetries at midrapidity in longitudinally polarized p + p collisions at √ s = 510 GeV, Phys. Rev. D 102 (2020) 032001, 10.1103/PhysRevD.102.032001

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U. A. Acharya et al., Improving constraints on gluon spinmomentum correlations in transversely polarized protons via midrapidity open-heavy-flavor electrons in p ↑ + p collisions at √ s = 200 GeV (2022)

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C. Aidala et al., Nuclear Dependence of the Transverse SingleSpin Asymmetry in the Production of Charged Hadrons at Forward Rapidity in Polarized p + p, p+Al, and p+Au Collisions at √sNN = 200 GeV, Phys. Rev. Lett. 123 (2019) 122001, 10.1103/PhysRevLett.123.122001

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S. Benic and Y. Hatta, Single spin asymmetry in forward ´ pA collisions: Phenomenology at RHIC, Phys. Rev. D 99 (2019) 094012, 10.1103/PhysRevD.99.094012

U. A. Acharya et al., Transverse single spin asymmetries of forward neutrons in p + p, p+Al and p+Au collisions at √sNN = 200 GeV as a function of transverse and longitudinal momenta, Phys. Rev. D 105 (2022) 032004, 10.1103/PhysRevD.105.032004

G. Mitsuka, (private communication), based on [42]

G. Mitsuka, Recently measured large AN for forward neutrons in p ↑A collisions at √ sNN = 200 GeV explained through simulations of ultraperipheral collisions and hadronic interactions, Phys. Rev. C 95 (2017) 044908, 10.1103/PhysRevC.95.044908




How to Cite

Fitzgerald DS. PHENIX Spin Physics Overview. Supl. Rev. Mex. Fis. [Internet]. 2022 Dec. 10 [cited 2023 Feb. 6];3(4):040908 1-10. Available from: