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

TL;DR

This study extends lattice QCD-based predictions of a $u d ar b ar b$ tetraquark by including heavy spin effects, confirming its bound state with quantum numbers $I(J^P)=0(1^+)$.

Contribution

It introduces a coupled-channel Schrödinger equation approach to incorporate heavy quark spin effects into lattice QCD potentials for tetraquark prediction.

Findings

Confirmed the existence of the $u d ar b ar b$ tetraquark with heavy spin effects.

Extended previous models by including heavy quark spins in the analysis.

Validated the bound state prediction with more comprehensive spin considerations.

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 Schr\"odinger equation for the anti-bottom-anti-bottom separation. Without taking heavy quark spins into account this approach predicted a $u d \bar b \bar b$ tetraquark bound state with quantum numbers $I(J^P) = 0(1^+)$. We now extend this Born-Oppenheimer approach with coupled channel Schr\"odinger equations allowing us to incorporate effects due to the heavy $\bar b$ spins. We confirm the existence of the $u d \bar b \bar b$ tetraquark.