Single Spin Asymmetry $A_N$ in Polarized Proton-Proton Elastic Scattering at $\sqrt{s}=200$ GeV

We report a high precision measurement of the transverse single spin asymmetry AN at the center of mass energy s=200 GeV in elastic proton–proton scattering by the STAR experiment at RHIC. The AN was measured in the four-momentum transfer squared t range 0.003⩽|t|⩽0.035 (GeV/c)2 , the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of AN 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 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.

Note:

12 pages, 6 figures

13.88.+e
13.85.Dz
Polarization
Elastic scattering
spin: asymmetry
pomeron: exchange
p p: elastic scattering
polarized beam: transverse
precision measurement
scattering amplitude

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