Old Tools for New Puzzles: From Toponium Physics to the Exotic Nature of X(3872)

Davide Germani discusses how established field-theory techniques help interpret precise ATLAS and CMS measurements of heavy-quark systems. The first case concerns top–antitop states near their production threshold, drawing on recent calculations by Paolo Nason and collaborators. Topics include threshold resummation, nonperturbative QCD corrections, and the way the top quark’s short lifetime controls the formation and decay of quasi-bound states at collider energies. The second case examines whether X(3872) is a compact exotic hadron or a weakly bound neutral D-meson molecule. A comparison of the conventional Flatté parametrization with an effective field theory containing a reversed-sign kinetic term clarifies the physical meaning of that term and its relationship to a negative effective range. The seminar shows how adapting established methods can address new anomalies and structures in hadron spectroscopy.