Gießen 2024 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Hadron Structure and Spectroscopy IV

HK 25.3: Talk

Tuesday, March 12, 2024, 18:15–18:30, HBR 14: HS 1

Spacelike electromagnetic form factors of Lambda- and Sigma-baryons — •Langtian Liu and Christian S. Fischer — Institut für Theoretische Physik, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany

An important goal of ongoing and future experiments is to explore spectra and transition form factors of baryons with non-zero strangeness. Of particular interest is the transition form factor γ^(*) Σ⁰ → Λ and γ^(*) Σ⁰(1382) → Λ in the time-like momentum region that can be extracted from Dalitz decays. On the road towards a theoretical description of these form factors we extend a covariant dynamical quark-diquark model for the baryon Faddeev equation to the strange-quark sector. Based on an excellent description of the mass spectrum of selected baryon octet and decuplet states and reasonable results for the nucleon form factors we determine the elastic electromagnetic form factors of Λ and Σ⁺, Σ⁰, Σ⁻, Σ⁰(1382) hyperons in the space-like region as well as the ones for the octet transition γ^(*) Σ⁰ → Λ. We discuss qualitative and quantitative features of the diquark-quark picture and compare systematically with previous results from a three-body Faddeev approach and lattice data where available.

Keywords: Hyperon; Quark-diquark Faddeev equation; Mass spectrum; Electromagnetic form factors; Transition form factors