We investigate the spin-flip component of the Pomeron using the single spin asymmetry, $A_N(t)$ in polarized elastic $pp$ scattering, arising from Coulomb-nuclear interference (CNI) in small-angle elastic scattering.
The previous analyses have missed the absorptive corrections to the Coulomb amplitude of $pp$ elastic scattering, which plays an important role. Namely, interference of ultra-peripheral and central collisions leads to significant changes in $A_N(t)$.
We found that the absorptive corrections considerably affect the results of the analysis of the single spin asymmetry data from
STAR data for $A_N(t)$ at $\sqrt{s}=200$ GeV. At such high energy, the Reggeon contribution is expected to be small so that one can study the Pomeron spin-flip component.