论文标题
参数狭窄的四夸克状态，其中包含一个重的夸克和一个重型古夸克
Parametrically narrow tetraquark states containing one heavy quark and one heavy antiquark
论文作者
论文摘要
本文着重于四夸克人，其中包含一个沉重的夸克和一个沉重的古夸克，在重量夸克群体进入无穷大的情况下。它扩展了针对四夸克开发的理论框架，该框架基于半古典分析和Born-oppenheimer近似。结果表明，对于足够小的夸克质量，参数狭窄的$ q \ bar {q}'q \ bar {q} $ tetraquarks必须以任意大型夸克质量的正式极限存在。该分析是独立的。它不需要对状态的结构或其衰减机制的假设，而不是直接从QCD推导的东西。这里的形式分析仅直接适用于具有较大角动量的四夸克人，因此不直接适用于实验观察到的四夸克候选者。我们还讨论了分析版本申请低角度动量状态所需的条件。是否可以通过晶格计算探索这种情况。当前的晶格计算表明未满足该条件。如果确认了这些初步计算，则对所观察到的包含$ \ bar {c} c $或$ \ bar {b} b $ pairs的四夸克共振的性质有很大的影响。它提高了观察到的四夸克人存在的可能性，不是因为魅力和底部夸克非常重，而是因为它们足够轻。
This paper focuses on tetraquarks containing one heavy quark and one heavy antiquark in the formal limit where the heavy quark masses go to infinity. It extends the theoretical framework developed for tetraquark containing two heavy quarks based on semi-classical analysis and the Born-Oppenheimer approximation. It is shown that for sufficiently small light quark masses, parametrically narrow $q\bar{q}'Q\bar{Q}$ tetraquarks must exist in the formal limit of arbitrarily large heavy quark masses. The analysis is model-independent; it requires no assumptions about the structure of the state or the mechanism of its decay beyond what can be deduced directly from QCD. The formal analysis here is only directly applicable to tetraquarks with large angular momentum and hence does not directly apply to experimentally observed tetraquark candidates. We also discuss the condition needed for a version of the analysis to apply for low angular momenta states. Whether this condition holds can be explored via lattice calculations. Current lattice calculations suggest that the condition is not met. If these preliminary calculations are confirmed, there are strong implications for the nature of the observed tetraquark resonances containing $\bar{c}c$ or $\bar{b}b$ pairs. It raises the possibility that the observed tetraquarks exist and are narrow not because the charm and bottom quarks are extremely heavy, but because they are sufficiently light.
