Light Mesons
Dr. José R. Peláez (Universidad Complutense, Madrid)

I will review the status and recent developments on light scalar meson spectroscopy. After explaining why these particles are of interest in several fields of physics, and what are the longstanding controversies about their existence and nature. Next, I will explain the developments in the precise determination of these meson properties, their spectroscopic classification, and also those suggesting that these states--contrary to ordinary mesons---are not predominantly made of a quark and an antiquark. In particular I will introduce Chiral Perturbation Theory as the Effective Lagrangian of QCD and how, together with other non-perturbative techniques like dispersion relations and unitarization techniques and the \(N_c\) behavior give strong support for this emerging picture.