Lattice QCD investigation of a b-bar b-bar u d tetraquark resonance

我们的主要目的是利用格点QCD研究量子数为I（J^P）= 0（1^−）的b-棒b-棒u d四夸克态共振的存在性，并确定其质量和宽度.在以前的工作的基础上晶格QCD势和玻恩-奥本海默近似，我们发现存在这样的共振的迹象。然而，在那里，已经使用了几种近似，特别是b-条夸克被认为是无限重的，而轻和重的自由度被分开处理。由于有限质量的b-条夸克被认为会削弱四夸克系统的束缚，因此在不采用这种近似的情况下进行全格点QCD计算是很重要和有趣的。这样的计算将提供有关重-重-轻-轻四夸克态的进一步见解，这是近年来引起人们极大兴趣的一个课题，特别是由于带电Z_c和Z_B四夸克态的实验发现。

Our main objective is to study the existence and to determine mass and width of a b-bar b-bar u d tetraquark resonance with quantum numbers I(J^P) = 0(1^−) using lattice QCD. In previous work based on lattice QCD potentials and the Born-Oppenheimer approximation we found indication for the existence of such a resonance. There, however, several approximations have been used, in particular the b-bar quarks have been considered as infinitely heavy and the light and heavy degrees of freedom have been treated separately. Since b-bar quarks of finite mass are expected to weaken binding of the four-quark system, it is important and interesting to perform a full lattice QCD computation, where such approximations are not employed. Such a computation will provide further insights concerning heavy-heavy-light-light tetraquarks, a topic which received considerable interest in recent years, in particular due to the experimental discovery of the electrically charged Z_c and Z_b tetraquark states.