$\Lambda(1405)$ observations in p+p and K$^-$-induced reactions

TL;DR

This paper investigates the production and spectral properties of the $ ext{Lambda}(1405)$ resonance in proton-proton and kaon-induced reactions, highlighting discrepancies with theoretical models and previous experiments, and emphasizing the need for further experiments.

Contribution

It presents new measurements of $ ext{Lambda}(1405)$ in p+p collisions at 3.5 GeV and discusses spectral shifts not explained by existing theories or prior data.

Findings

Spectral function shift in p+p reactions differs from theoretical predictions.

Discrepancies observed between p+p and K$^-$-induced reaction results.

Calls for new experiments with stopped and in-flight K$^-$ to clarify the initial state.

Abstract

The $\Lambda(1405)$ production in p+p collisions at 3.5 GeV and K$^-$-induced reactions is discussed. The shift of the measured spectral function of the $\Lambda(1405)$ in p+p reactions does not match either theoretical calculations for p+p reactions or experimental observation in previous K$^-$-induced reactions. New experiments with stopped and in-flight $K^-$ are needed to study this initial state more in detail. The state of the art of the analysis is discussed.