Two-pole structure of the $\Lambda(1405)$: A Lattice QCD study of the coupled-channel $\pi\Sigma-\bar{K}N$ (2/5)

by Ms Bárbara Cid-Mora (University of Darmstadt)

Monday 13 May 2024, 13:15 → 14:15 Europe/Berlin

1.207 (IRIS)

This talk presents the results of the first coupled-channel meson-baryon $\pi\Sigma-\bar{K}N$ calculation from lattice QCD in the $\Lambda(1405)$ region. The relevant methods to compute correlation functions and extract finite-volume energy spectra are presented, as well as the method to study scattering amplitudes. This study was carried out using a single ensemble with pion mass $m_{\pi}=200$ MeV and kaon mass $m_K = 487$ MeV, and included additional sets of multi-hadron operators. Once the stationary-state energy levels were reliably extracted, the Lüscher formalism was employed to study scattering amplitudes. The final results are consistent with the two-pole picture, where every parametrization of the two-channel $\textit{K}$-matrix exhibits two poles in the complex energy plane. The location of these poles corresponds to a virtual bound state below the $\pi\Sigma$ threshold and a resonance pole below the $\bar{K}N$.