Coulomb phase corrections to the transverse analyzing power $A_N(t)$ in high energy forward proton-proton scattering

TL;DR

This paper evaluates Coulomb phase corrections to the transverse analyzing power in high energy forward proton-proton scattering, highlighting their impact on interpreting spin-flip amplitudes in precision measurements.

Contribution

It provides a detailed calculation of Coulomb phase shifts for electromagnetic and hadronic amplitudes, clarifying their small but potentially significant effects on experimental analysis.

Findings

Small discrepancy between spin-flip and non-flip phases, negligible at high energies.

Electromagnetic corrections can significantly alter the hadronic spin-flip amplitude.

Coulomb phase shifts are crucial for accurate interpretation of polarization data.

Abstract

Study of polarized proton-proton elastic scattering in the Coulomb-nuclear interference region allows one to measure the forward hadronic single spin-flip amplitude including its phase. However, in a precision experimental data analysis, a phase shift correction $\delta_C$ due to the long distance Coulomb interaction should be taken into account. For unpolarized scattering, $\delta_C$ is commonly considered as well established. Here, we evaluate the Coulomb phase shifts for the forward elastic proton-proton single spin-flip electromagnetic and hadronic amplitudes. Only a small discrepancy between the spin-flip and non-flip phases was found which can be neglected in the high energy forward elastic $\mathit{pp}$ studies involving transverse spin. Nonetheless, the effective alteration of the hadronic spin-flip amplitude by the long distance electromagnetic corrections can be essential for interpretation of the experimental results.