How the Z(c)(3900) reveals the spectra of charmonium hybrids and tetraquarks.

The recently discovered Z(c)(3900) meson is a flavor-exotic tetraquark whose constituents consist of a charm quark and antiquark and a light quark and antiquark. We identify such heavy tetraquark mesons as analogs of quarkonium hybrids, with the gluon field replaced by an isospin-1 excitation of the gluon and light-quark fields. Given the identification of Y(4260) as a ground-state charmonium hybrid, lattice QCD calculations of the charmonium spectrum by the Hadron Spectrum Collaboration can be used to estimate the masses of the four lowest spin-symmetry multiplets of charmonium hybrids. We make the assumption that the isospin-1 Born-Oppenheimer potentials, whose energy levels are tetraquarks, have the same shapes as the flavor-singlet Born-Oppenheimer potentials, whose energy levels are hybrids. Given the identification of Z(c)(3900) as a charmonium tetraquark, lattice QCD calculations of the charmonium hybrid spectrum can then be used to estimate the masses of the four lowest spin-symmetry multiplets of charmonium tetraquarks.