Born-Oppenheimer Effective Field Theory as a unified framework for all the XYZ exotics

Abstract

We discuss some recent applications of the Born-Oppenheimer effective field theory (BOEFT) formalism, directly derived from QCD and grounded in scale separation and symmetries, to hadronic systems containing two heavy quarks. This formalism provides a unified description of both ordinary and exotic quarkonium states (i.e., hybrids, tetraquarks, pentaquarks, ...) dynamics via coupled Schr\"odinger equations, whose potentials are computable on the lattice. The aim is to unveil the elusive pattern of the XYZ exotic hadrons. Here, we apply the BOEFT formalism to the $\chi_{c1}(3872)$, $T_{cc}(3875)^+$, and their bottom counterparts. Moreover, we assess the threshold effects on the quarkonium spectrum and discuss the inclusive production cross section for $\chi_{c1}(3872)$.