Mass spectra for the cc(b)over-bar(b)over-bar and bb(c)over-bar(c)over-bar tetraquark states

We have studied the masse spectra for the cc (b) over bar(b) over bar and bb (c) over bar(c) over bar tetraquark states with quantum numbers J(P) = 0(+/-), 1(+/-), and 2(+). We systematically construct the interpolating currents with various spin-parity quantum numbers and calculate their two-point correlation functions in the framework of QCD moment sum rule method. Our calculations show that the masses are about 12.3-12.4 GeV for the positive parity cc (b) over bar(b) over bar tetraquark ground states with J(P) = 0(+), 1(+), 2(+), while 12.8-13.1 GeV for the negative parity channels with J(P) = 0(-), 1(-). The mass predictions for the positive parity cc (b) over bar(b) over bar ground states are lower than the BcBc threshold, implying that these tetraquarks can only decay via weak interaction and thus are expected to be stable and narrow.