Double spin asymmetries ANN and ASS at

Abstract

We present the first measurements of the double spin asymmetries A N N and A SS at √ s = 200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy IonCollider (RHIC). The data were collected in the four momentum transfer t range 0.01 ≤ |t| ≤ 0.03 (GeV/c) 2 . The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes φ 2 and φ 4 at small |t| as well as on the difference ∆σ T between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations.PACS numbers: 13.85.Dz and 13.88.+e 2