A lattice investigation of exotic tetraquark channels

We perform an n_f=2+1 lattice study of a number of channels where past claims exist in the literature for the existence of strong-interaction-stable light-heavy tetraquarks. We find no evidence for any such deeply-bound states, beyond the J^P=1^+, I=0 udb̅b̅ and I=1/2 lsb̅b̅ states already identified in earlier lattice studies. We also describe a number of systematic improvements to our previous lattice studies, including working with larger m_π L to better suppress possible finite volume effects, employing extended sinks to better control excited-state contamination, and expanding the number of operators used in the GEVP analyses. Our results also allow us to rule out several phenomenological models which predict significant tetraquark binding in channels where no such binding is found.