Corrections to the Elastic Proton-Proton Analyzing Power Parametrization at High Energies

TL;DR

This paper refines the parametrization of proton-proton analyzing powers at high energies by evaluating corrections due to electromagnetic form factors and spin-flip amplitudes, impacting precise polarization measurements.

Contribution

It introduces necessary corrections to the analyzing power parametrization used in high-energy proton-proton elastic scattering studies.

Findings

Corrections due to form factors and spin-flip amplitudes are comparable to experimental uncertainties.

Proposed corrections influence the determination of the real-to-imaginary amplitude ratio .

Alterations may affect interpretations of elastic scattering data and polarization measurements.

Abstract

The HJET Polarized Atomic Hydrogen Gas Jet Target polarimeter (HJET) polarimeter was designed to measure the absolute polarization of the proton beams at the Relativistic Heavy Ion Collider. In these measurements, the small scattering angle elastic $pp$ single $A_N(t)$ and double $A_{NN}(t)$ spin analyzing powers can be precisely determined. The experimental accuracy achieved at HJET requires corrections to the $A_N(t)$ parametrization, conventionally used for such studies. In this paper we evaluate the corrections to the analyzing powers due to (i) the differences between the electromagnetic and hadronic form factors and (ii) the $m_p^2/s$ terms in the elastic spin-flip $pp$ electromagnetic amplitude. The corresponding alterations of the evaluated hadronic spin-flip amplitudes are about the same as the experimental uncertainties of the HJET measurements. The proposed corrections may have implications for the elastic $pp$ forward real-to-imaginary amplitude ratios $\rho$ determined in unpolarized $pp$ experiments.