Reexamination of antinucleon-nucleon interactions in covariant chiral effective field theory

TL;DR

This paper develops a relativistic covariant chiral effective field theory approach to antinucleon-nucleon interactions, comparing it with heavy baryon methods and identifying potential bound states near the threshold.

Contribution

It introduces a hybrid covariant chiral EFT model for antinucleon-nucleon interactions and demonstrates its effectiveness in describing phase shifts and inelasticities, with implications for observed states.

Findings

Relativistic approach shows faster convergence than non-relativistic methods.

Phase shifts and inelasticities are well described up to J≤1.

Potential bound states near the N̄N threshold are identified.

Abstract

Motivated by the recent progress in developing high-precision relativistic chiral nucleon-nucleon interactions, we study the antinucleon-nucleon interaction in a hybrid approach where the real part of the potential is constructed in the leading-order covariant chiral effective field theory, and the imaginary part is described following the procedure adopted in the heavy baryon chiral effective field theory. The phase shifts and inelasticities with $J\leq 1$ are obtained and compared to those calculated in the next-to-leading order heavy baryon chiral effective field theory. For most partial waves, the descriptions of phase shifts and inelasticities in the hybrid approach are comparable to those in the next-to-leading order heavy baryon chiral effective field theory, confirming the relatively faster convergence of the relativistic approach observed in the nucleon-nucleon sector. In addition, we search for bound states/resonances near the $\bar{N}N$ threshold and find several structures that can be associated with those states recently observed by the BESIII Collaboration.