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arXiv 1111.2404hep-lathep-th
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Wilson手征微扰理论低能常数的限制

Constraint on the Low Energy Constants of Wilson Chiral Perturbation Theory

Maxwell T. Hansen, Stephen R. Sharpe

摘要:

Wilson手征微扰理论(WChPT)是描述含有Wilson或扭曲质量费米子的格点量子色动力学长距离性质的有效场论。在这里,我们考虑WChPT的理论与两个轻口味的威尔逊费米子或一个单一的轻扭曲质量费米子。离散化误差将三个低能常数(LEC)引入到O(a^2)处的部分猝灭的WChPT中,通常称为W '_6、W'_7和W '_8。在非零α下,理论的相结构依赖于2 W '_6 + W'_8的符号,而格点Hermitian Wilson-Dirac算符的谱依赖于所有三个常数。有人认为,基于固定拓扑电荷的配分函数的正性,以及在ChPT的ε-区域中出现的分次群积分的收敛性,存在对LEC的约束,该约束产生于基础晶格理论。特别地,对于W '_6 = W'_7 = 0,找到的约束是W '_8 \le 0。在这里,我们提供了一个替代线的论点,基础上的部分淬火理论的质量不等式。我们发现W '_8 \le 0,与W'_6和W '_7的值无关。我们的约束意味着2 W '_6>| W'_8|如果相图是由一阶情景描述的,正如最近的模拟所表明的那样,对于一些行动的选择是这样的。

英文摘要:

Wilson chiral perturbation theory (WChPT) is the effective field theory describing the long- distance properties of lattice QCD with Wilson or twisted-mass fermions. We consider here WChPT for the theory with two light flavors of Wilson fermions or a single light twisted-mass fermion. Discretization errors introduce three low energy constants (LECs) into partially quenched WChPT at O(a^2), conventionally called W'_6, W'_7 and W'_8 . The phase structure of the theory at non-zero a depends on the sign of the combination 2W'_6 + W'_8, while the spectrum of the lattice Hermitian Wilson-Dirac operator depends on all three constants. It has been argued, based on the positivity of partition functions of fixed topological charge, and on the convergence of graded group integrals that arise in the epsilon-regime of ChPT, that there is a constraint on the LECs arising from the underlying lattice theory. In particular, for W'_6 = W'_7 = 0, the constraint found is W'_8 \le 0. Here we provide an alternative line of argument, based on mass inequalities for the underlying partially quenched theory. We find that W'_8 \le 0, irrespective of the values of W'_6 and W'_7. Our constraint implies that 2W'_6 > |W'_8| if the phase diagram is to be described by the first-order scenario, as recent simulations suggest is the case for some choices of action.

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