Born-Oppenheimer Approximation for the XYZ Mesons

Understand

Many of the XYZ mesons discovered in the last decade can be identified as bound states in Born-Oppenheimer (B-O) potentials for a heavy quark and antiquark.

• They include quarkonium hybrids, which are bound states in excited flavor-singlet B-O potentials, and quarkonium tetraquarks, which are bound states in flavor-nonsinglet B-O potentials.
• We present simple parameterizations of the deepest flavor-singlet B-O potentials.
• We infer the deepest flavor-nonsinglet B-O potentials from lattice QCD calculations of static adjoint mesons.