Single spin asymmetry AN in polarized proton-proton elastic scattering at √s=200 GeV

We report a high precision measurement of the transverse single spin asymmetry A(N) at the center of mass energy root s = 200 GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The A(N) was measured in the four-momentum transfer squared t range 0.003 <= vertical bar t vertical bar <= 0.035 (GeV/c)(2), the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of A(N) and its t-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this root s, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering. (c) 2013 Elsevier B.V. All rights reserved.