Speaker: Arkaitz Rodas Bilbao, Old Dominion University/JLab
Title: Studying non-ordinary resonances from first-principles QCD
Abstract: The non-perturbative nature of QCD prevents us from understanding the emergence of many hadrons in simple terms. From quark models to effective field theories, the unambiguous determination of several of the states in the QCD spectrum remains unsolved. The rigorous, theoretical approach to studying these states from first principles is lattice QCD. In this talk, we will review some lattice QCD determinations of different hadrons, focusing on the non-ordinary $\sigma$ resonance. The connection between two-to-two scattering amplitudes and more challenging reactions, aiming at extracting structure information on these states, is briefly summarized. Finally, we present the role that modern reaction-amplitude and dispersion relation techniques play in the model-independent determination of the $\sigma$ parameters and motivate future work on other scalar mesons.