标题： 动力学Wilson费米子的手征性质 显示英文标题

标题： Chiral properties of dynamical Wilson fermions

摘要： 我们考虑用改进的威尔逊费米子在格点正则化下的双味QCD。 在这个表述中，手征对称性在O(a)阶被显式破坏，因此若要使同位旋矢量轴向流满足直到O(a^2)阶格点修正的小的连续Ward-Takahashi恒等式，它们也需要改善以及有限的重整化。 讨论了在粗格点间距处的算法困难，在这种情况下HMC受到扭曲的Dirac谱的影响。 这被证明是一种截断效应，随着格点间距的减小，它会迅速消失。 发现多项式混合蒙特卡洛算法在存在特别小的本征值时表现显著更好。 通过扩展先前使用的方法，轴向流的改善和重整化均以非微扰的方式实现，这些方法是在施罗丁格函数框架下制定的相关函数。 在这两种情况下，都是通过在有限格点间距下强制实施连续Ward恒等式来实现的。 两者结合，这在格点间距的平方阶上恢复了同位旋手征对称性。 几乎不需要额外的努力，局部矢量流的归一化因子也可以得到。 显示英文摘要

摘要： We consider two-flavor QCD in the lattice regularization with improved Wilson fermions. In this formulation chiral symmetry is explicitly broken at order a and hence the isovector axial currents require improvement as well as a finite renormalization if they are to satisfy continuum Ward--Takahashi identities up to small lattice corrections of O(a^2). Algorithmic difficulties at coarse lattice spacings, where HMC suffers from a distorted Dirac spectrum, are discussed. This is shown to be a cutoff effect, which disappears rapidly as the lattice spacing is decreased. An alternative algorithm, the polynomial hybrid Monte Carlo algorithm, is found to perform significantly better in the presence of exceptionally small eigenvalues. Extending previously used methods both the improvement and the renormalization of the axial current are implemented non--perturbatively in terms of correlation functions formulated in the framework of the Schroedinger functional. In both cases this is achieved by enforcing continuum Ward identities at finite lattice spacing. Together, this restores the isovector chiral symmetry to quadratic order in the lattice spacing. With little additional effort the normalization factor of the local vector current is also obtained.