# Antinucleon-nucleon interaction at next-to-next-to-next-to-leading order in chiral effective field theory

## TL;DR

This paper presents high-precision antinucleon-nucleon interaction results at next-to-next-to-next-to-leading order in chiral EFT, using a new regularization scheme and an improved uncertainty estimation, achieving excellent agreement with experimental data.

## Contribution

It introduces a novel local regularization scheme and an alternative uncertainty estimation method for chiral EFT applied to $ar NN$ interactions, with comprehensive data fitting and analysis.

## Key findings

- Achieves excellent fit to $ar NN$ phase shifts and inelasticities.
- Accurately reproduces $ar pp$ observables up to 300 MeV.
- Describes differential cross sections and analyzing powers well up to 200-250 MeV.

## Abstract

Results for the antinucleon-nucleon ($\bar NN$) interaction obtained at next-to-next-to-next-to-leading order in chiral effective field theory (EFT) are reported. A new local regularization scheme is used for the pion-exchange contributions that has been recently suggested and applied in a pertinent study of the $NN$ force within chiral EFT. Furthermore, an alternative strategy for estimating the uncertainty is utilized that no longer depends on a variation of the cutoffs. The low-energy constants associated with the arising contact terms are fixed by a fit to the phase shifts and inelasticities provided by a phase-shift analysis of $\bar pp$ scattering data. An excellent description of the $\bar NN$ amplitudes is achieved at the highest order considered. Moreover, because of the quantitative reproduction of partial waves up to $J=3$, there is also a nice agreement on the level of $\bar pp$ observables. Specifically, total and integrated elastic and charge-exchange cross sections agree well with the results from the partial-wave analysis up to laboratory energies of $300$ MeV, while differential cross sections and analyzing powers are described quantitatively up to $200$-$250$ MeV. The low-energy structure of the $\bar NN$ amplitudes is also considered and compared to data from antiprotonic hydrogen.