Signature of the $\Lambda(1405)$ resonance in neutron spectra from the $K^-+d$ reaction

TL;DR

This study uses advanced three-body calculations to identify the signature of the $ ext{Lambda}(1405)$ resonance in neutron spectra from $K^-$ interactions with deuterons, revealing the resonance's features through deviation spectrum analysis.

Contribution

It demonstrates that the deviation spectrum method can effectively isolate the $ ext{Lambda}(1405)$ resonance signature in neutron spectra, despite kinematic masking in direct spectra, using coupled channel Faddeev equations.

Findings

Kinematic effects mask the resonance in direct spectra.

Deviation spectrum method isolates the $ ext{Lambda}(1405)$ signature.

Different $ar{K}N- ext{pi}\Sigma$ models affect the neutron spectra.

Abstract

Neutron spectra from the reaction $K^-+d\rightarrow \pi+\Sigma+n$ were calculated in the energy range $E^{cm}_{K^-}= 0-50\ MeV$ using coupled channel Faddeev equations for the description of the $\bar KNN-\pi\Sigma N$ three-body system. The aim was to trace the signature of the $\Lambda(1405)$ resonance in the spectra. We found, that while in the direct spectra kinematic effects mask completely the peak corresponding to the resonance, the deviation spectrum method [1] is able to eliminate kinematics and differentiate between different models of $\Lambda(1405)$. Four different phenomenological $\bar{K}N-\pi\Sigma$ interactions were used in order to study the effect of their pole positions on the neutron spectra.