The $\Lambda(1405)$ in resummed chiral effective field theory

TL;DR

This paper investigates the $ ext{Lambda}(1405)$ resonance using a Lorentz-invariant chiral effective field theory, revealing its two-pole structure through unitarized meson-baryon scattering analysis.

Contribution

It introduces a Lorentz-invariant formulation with off-shell effects and subtractive renormalization to study the $ ext{Lambda}(1405)$ resonance in detail.

Findings

Confirmed the two-pole structure of $ ext{Lambda}(1405)$

Demonstrated the importance of higher-order terms

Provided a renormalized scattering amplitude analysis

Abstract

We study the unitarized meson-baryon scattering amplitude at leading order in the strangeness $S=-1$ sector using time-ordered perturbation theory for a manifestly Lorentz-invariant formulation of chiral effective field theory. By solving the coupled-channel integral equations with the full off-shell dependence of the effective potential and applying subtractive renormalization, we analyze the renormalized scattering amplitudes and obtain the two-pole structure of the $\Lambda(1405)$ resonance. We also point out the necessity of including higher-order terms.