Probing Gluon Spin-Momentum Correlations in Transversely Polarized Protons through Midrapidity Isolated Direct Photons in p+p Collisions at s=200GeV

Abstract
Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in p+p collisions at s=200GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a 50-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.
Funding Information
  • Brookhaven National Laboratory
  • Nuclear Physics
  • National Science Foundation
  • Abilene Christian University
  • Research Foundation for the State University of New York
  • Vanderbilt University
  • Ministry of Education, Culture, Sports, Science and Technology
  • Japan Society for the Promotion of Science
  • National Natural Science Foundation of China
  • Hrvatska Zaklada za Znanost
  • Ministarstvo znanosti i obrazovanja
  • Ministerstvo Školství, Mládeže a T?lovýchovy
  • Centre National de la Recherche Scientifique
  • Commissariat á l’Énergie Atomique et aux Énergies Alternatives
  • Institut National de Physique Nucléaire et de Physique des Particules
  • Bundesministerium für Bildung und Forschung
  • Deutscher Akademischer Austauschdienst
  • Alexander von Humboldt-Stiftung
  • Nemzeti Kutatási Fejlesztési és Innovációs Hivatal
  • OTKA
  • Department of Atomic Energy, Government of India
  • Israel Science Foundation
  • National Research Foundation of Korea
  • Lahore University of Management Sciences
  • Ministry of Education and Science of the Russian Federation
  • Russian Academy of Sciences
  • Federal Agency of Atomic Energy of the Russian Federation
  • Vetenskapsrådet
  • Knut och Alice Wallenbergs Stiftelse
  • CRDF Global
  • Fulbright Association
  • United States-Israel Binational Science Foundation
  • EFOP
  • ÚNKP
  • Basic Science Research
  • SRC
  • Hungarian American Enterprise Scholarship Fund