Tetraquarks with exotic flavor quantum numbers at large Nc in QCD(AS)

It is shown that the large Nc limit of QCD with quarks in the two-index antisymmetric color representation [QCD(AS)] has narrow tetraquark states with exotic flavor quantum numbers. They decay into mesons with a width that is parametrically O(1/Nc2). Tetraquarks with nonexotic quantum numbers mix at leading order with mesons of the same overall quantum numbers. QCD(AS) at Nc=3 corresponds to ordinary QCD; its large Nc limit represents an alternative starting point for a 1/Nc expansion to the standard one with quarks in the fundamental color representation.