Title: Sigma term physics

 

Speaker: Prof. Ulf-G. Meissner (Universit at Bonn & Forschungszentrum Julich)

 

Time: 3:00 PM, Jul. 16th (Tuesday), 2019 

Place: R319, Theoretical Physics Division  

Abstract : The pion-nucleon sigma term σπN is an important quantity in strong interaction phenomenology and in searches for physics beyond the Standard Model. After a broad introduction, I discuss its precise extraction from pion-nucleon scattering data based on Roy-Steiner equations. In this context, tensions with recent lattice determination of σπN are discussed. Then, I turn to the flavor decomposition of the sigma term and the question of strangeness in the nucleon. Using different variants of baryon chiral perturbation theory, I discuss our present understanding and future improvements.