Including heavy spin effects in the prediction of a $\bar{b}\bar{b}ud$ tetraquark with lattice QCD potentials

Abstract

We investigate spin effects in four-quark systems consisting of two heavy anti-bottom 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 Schrödinger equation for the anti-bottom-anti-bottom separation. Without taking heavy quark spins into account this approach predicted a $ud\bar{b}\bar{b}$ tetraquark bound state with quantum numbers $I(J^P)=0(1^{+})$. We now extend this Born-Oppenheimer approach with coupled channel Schrödinger equations allowing us to incorporate effects due to the heavy $\bar{b}$ spins. We confirm the existence of the $ud\bar{b}\bar{b}$ tetraquark.

Comments: 9 pages, 4 figures, 1 table