Polarization observables in low-energy antiproton-proton scattering

TL;DR

This paper analyzes polarization effects in low-energy antiproton-proton scattering, providing new predictions for unmeasured observables based on an improved partial-wave analysis, and explores the feasibility of polarizing antiproton beams.

Contribution

It introduces a new energy-dependent partial-wave analysis for antiproton-proton scattering data below 925 MeV/c, predicting polarization observables and beam polarization feasibility.

Findings

Significant spin effects observed, especially in charge-exchange scattering.

Feasibility of polarizing antiproton beams using polarized proton targets.

Predictions for unmeasured polarization observables.

Abstract

We investigate the polarization parameters in low-energy antiproton-proton elastic ($\bar{p}p\rightarrow\bar{p}p$) and charge-exchange ($\bar{p}p\rightarrow\bar{n}n$) scattering. The predictions for unmeasured observables are based on our new energy-dependent partial-wave analysis of all antiproton-proton scattering data below 925 MeV/$c$ antiproton laboratory momentum, which gives an optimal description of the existing database. Sizable and remarkable spin effects are observed, in particular for charge-exchange scattering. These result from the spin dependence of the long- and medium-range one- and two-pion exchange antinucleon-nucleon potential and the state dependence of the parametrized short-range interaction. We study the possibility of polarizing a circulating antiproton beam with a polarized proton target by exploiting the spin dependence of the $\bar{p}p$ total cross section. It appears feasible to achieve a significant transverse polarization of an antiproton beam within a reasonable time.