Measurement of Transverse Single-Spin Asymmetries for Midrapidity Production of Neutral Pions and Charged Hadrons in Polarized p + p Collisions at √s = 200 GeV

PHENIX Collaboration

Enokizono Akitomo

Hachiya Takashi

Homma Kensuke

Kohama Takeshi

Nakamura Tomoaki

Shigaki Kenta

Sugitate Toru

Physical Review Letters

Transverse single-spin asymmetries to probe the transverse-spin structure of the proton have been measured for neutral pions and nonidentified charged hadrons from polarized proton-proton collisions at midrapidity and s=200GeV. The data cover a transverse momentum (pT) range 1.0-5.0GeV/c for neutral pions and 0.5-5.0GeV/c for charged hadrons, at a Feynman-x value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within errors of a few percent. In addition, the inclusive charged hadron cross section at midrapidity from 0.5<pT<7.0GeV/c is presented and compared to next-to-leading order perturbative QCD (pQCD) calculations. Successful description of the unpolarized cross section above ∼2GeV/c suggests that pQCD is applicable in the interpretation of the asymmetry results in the relevant kinematic range.

quantum chromodynamics

proton-proton inclusive interactions

protons

baryon spin

polarisation in elementary particle interactions

eng

American Physical Society

Copyright (c) 2005 The American Physical Society.

[ISSN] 0031-9007

[DOI] 10.1103/PhysRevLett.95.202001

[NCID] AA00773679

[DOI] http://dx.doi.org/10.1103/PhysRevLett.95.202001