QQ(s)over-bar(s)over-bar tetraquarks in the chiral quark model

The low-lying S-wave QQ (s) over bar(s) over bar (Q = c, b) tetraquark states with 1(J(P)) = 0(0(+)), 0(1(+)) and 0(2(+)) are systematically investigated in the framework of complex scaling range of chiral quark model. Every structure including meson-meson, diquark-antidiqualk and K-type configurations, and all possible color channels in four-body sector are considered by means of a commonly extended variational approach, Gaussian expansion method. Within the studied mass region, several narrow and wide resonance states arc obtained for cc (s) over bar(s) over bar and bb (s) over bar(s) over bar tetraquarks with I(J(P)) = 0(0(+)) and 0(2(+)). Meanwhile, narrow resonances for cb (s) over bar(s) over bar tetraquarks arc also found in I(J(P)) = 0(0(+)), 0(1(+)) and 0(2(+)) states. The possibility of fmding tetraquark structures with masses similar to 0.6 GeV above the non-interacting hadron-hadron thresholds (and not close to them) is a feature related with the absence of the one-pion exchange interaction in the QQ (s) over bar(s) over bar sector and thus it could deserve experimental confirmation.