# SPIN 2018

9-14 September 2018
University of Ferrara
Europe/Rome timezone
23RD INTERNATIONAL SPIN SYMPOSIUM

## The Pomeron spin-flip and its measurements

11 Sep 2018, 17:05
25m

### A8

Parallel Sessions Spin Physics in Nuclear Reactions and Nuclei

### Speaker

Michal Krelina (Universidad Técnica Federico Santa María)

### Description

We investigate the spin-flip component of the Pomeron using the single spin asymmetry, $A_N(t)$, arising from Coulomb-nuclear interference (CNI) in small-angle elastic scattering. The study of elastic proton-nucleus scattering is important because it suppresses or excludes the contributions from iso-vector Reggeons which are predominantly spin-flip, and might have a significant impact on the results of fixed-target experiments at RHIC. However, previous theoretical attempts fail to explain the recent data from the RHIC on polarized proton-gold scattering, exposing a nontrivial $t$-dependence of $A_N$, strongly contradicting theoretical predictions. We found that the absorptive corrections in the Coulomb amplitude of $pA$ elastic scattering play a significant role. Namely, interference of ultra-peripheral and central collisions leads to a dramatic change in $A_N(t)$. We also include less significant corrections from Gribov inelastic shadowing, $NN$ correlations, and Odderon. Finally, we present that the non-zero hadron spin-flip amplitude is required to describe the single spin asymmetry proton and nuclear data. This allows us to make conclusions about the spin-flip pomeron behavior and its impact.

### Primary author

Michal Krelina (Universidad Técnica Federico Santa María)

### Co-author

Prof. Boris Kopeliovich (UTFSM)

 Slides