标题： 两体有限体积矩阵元的一致性检查：I. 守恒流和束缚态 显示英文标题

标题： Consistency checks for two-body finite-volume matrix elements: I. Conserved currents and bound states

摘要： 最近，已经开发出一个框架来研究由外部电流探测的两个强子态的流形因子。 该方法基于将使用数值格点QCD计算的有限体积矩阵元与相应的无限体积可观测量联系起来。 由于该形式化过程较为复杂，提供最终结果的非平凡检验以及探索可以提取更直接预测的极限情况非常重要。 在本工作中，我们在这两个方面都提供了例子。 首先，我们表明，在守恒矢量电流的情况下，该形式化确保守恒电荷的有限体积矩阵元与体积无关，并等于两粒子态的总电荷。 其次，我们研究了两粒子束缚态的含义。 我们证明无限体积极限再现了预期的矩阵元，并推导了对于标量电流的这一结果的领先有限体积修正。 最后，我们提供了对未来格点QCD计算氘核标量电荷的体积效应大小的数值估计。 我们发现，这些效应在现实格点体积下完全主导了无限体积结果，并且应用当前形式化以解析地去除一系列领先的体积修正，对于可靠地提取状态的无限体积电荷至关重要。 显示英文摘要

摘要： Recently, a framework has been developed to study form factors of two-hadron states probed by an external current. The method is based on relating finite-volume matrix elements, computed using numerical lattice QCD, to the corresponding infinite-volume observables. As the formalism is complicated, it is important to provide non-trivial checks on the final results and also to explore limiting cases in which more straightforward predications may be extracted. In this work we provide examples on both fronts. First, we show that, in the case of a conserved vector current, the formalism ensures that the finite-volume matrix element of the conserved charge is volume-independent and equal to the total charge of the two-particle state. Second, we study the implications for a two-particle bound state. We demonstrate that the infinite-volume limit reproduces the expected matrix element and derive the leading finite-volume corrections to this result for a scalar current. Finally, we provide numerical estimates for the expected size of volume effects in future lattice QCD calculations of the deuteron's scalar charge. We find that these effects completely dominate the infinite-volume result for realistic lattice volumes and that applying the present formalism, to analytically remove an infinite-series of leading volume corrections, is crucial to reliably extract the infinite-volume charge of the state.