In this work we investigate the existence of bound states for doubly heavy tetraquark systems $ \bar{ Q}\bar{ Q}'qq' $ in a full lattice-QCD computation, where heavy bottom quarks are treated in the framework of non-relativistic QCD. We focus on three systems with quark content $ \bar{ b}\bar{ b}ud $, $ \bar{ b}\bar{ b}us $ and $ \bar{ b}\bar{ c}ud $. We show evidence for the existence of $ \bar{ b}\bar{ b}ud $ and $ \bar{ b}\bar{ b}us $ bound states, while no binding appears to be present for $ \bar{ b}\bar{ c}ud $. For the bound four-quark states we also discuss the importance of various creation operators and give an estimate of the meson-meson and diquark-antidiquark percentages.
Categories: hep-lat