Including heavy spin effects in the prediction of a (b)over-bar (b)over-bar ud tetraquark with lattice QCD potentials

We investigate spin effects in four-quark systems consisting of two heavy antibottom quarks and two light up/down quarks. To this end, we use the Born-Oppenheimer approximation. We utilize potentials of two static antiquarks in the presence of two quarks of finite mass computed via lattice QCD and solve a coupled-channel Schrodinger equation for the antibottom-antibottom separation. Without taking heavy quark spins into account, this approach predicted a ud (b) over bar (b) over bar tetraquark bound state with quantum numbers I(J(P)) =0(1(+)). We now extend this Born-Oppenheimer approach with coupled-channel Schrodinger equations, allowing us to incorporate effects due to the heavy (b) over bar spins. We confirm the existence of the ud (b) over bar (b) over bar tetraquark.