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

我们的主要目的是利用晶格QCD研究量子数为I(J^P) = 0（1^−）的b-bar b-bar u - d四夸克共振的存在性，并确定其质量和宽度。在先前基于晶格QCD势和Born-Oppenheimer近似的工作中，我们发现了这种共振存在的迹象。然而，这里使用了几种近似，特别是b-棒夸克被认为是无限重的，轻自由度和重自由度被分开处理。由于有限质量的b-bar夸克被认为会削弱四夸克体系的结合，因此在不采用这种近似的情况下进行全晶格QCD计算是重要而有趣的。这样的计算将提供有关重-重-轻-轻四夸克的进一步见解，这是近年来引起相当大兴趣的主题，特别是由于带电的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.