Masses of doubly heavy tetraquarks QQq̄n̄ with JP=1+.

In this paper, we apply the method of QCD sum rules to study the doubly heavy tetraquark states Q Q q ̄ n ̄ with spin-parity J P = 1 + and strangeness S = 0 , − 1 using careful estimates of the Borel and threshold parameters involved. Masses of the doubly bottom and charmed tetraquarks with isospin I = 0 , 1 / 2 , 1 are computed precisely via taking into account multifarious condensates up to dimension 10. Compared with the two-heavy meson thresholds, we find that all nonstrange doubly-bottom tetraquarks and a doubly-charmed tetraquarks associated with J 3 with J P = 1 + are stable against strong decay into two bottom mesons while a doubly-charmed tetraquark associated with current J 2 is unstable against strong decay. By the way, weak decay widths of the doubly bottom tetraquarks are also given. [ABSTRACT FROM AUTHOR]