标题： 动态和部分无味两味QCD中的标量介子：格点结果和手征环 显示英文标题

标题： Scalar meson in dynamical and partially quenched two-flavor QCD: lattice results and chiral loops

摘要： 这是一项在具有两个动态夸克的格点上对最轻的非单态标量$q\bar q$状态的探索性研究。 使用领域墙费米子处理海夸克和价夸克，在反格点间距为1.7 GeV的16^3*32格点上进行。 我们从动态关联函数的指数时间依赖性中提取标量介子质量为1.58(34) GeV，其中$m_{val}=m_{sea}$和 N_f=2。 由于来自动态关联函数的统计误差条较大，我们还分析了部分熄灭的格点关联函数，其中$m_{val}$不等于$m_{sea}$。 它们对于$m_{val}>=m_{sea}$是正的，对于$m_{val}<m_{sea}$是负的。 为了理解这种显著的部分熄灭效应，我们在部分熄灭的ChPT中推导了标量关联函数，并发现它能很好地描述格点关联函数。 部分淬火ChPT中的主要非物理贡献来自两个伪标量场的交换，在大t时对于$m_{val}>=m_{sea}$为正，对于$m_{val}<m_{sea}$为负。在从部分淬火格点关联函数中减去这一非物理贡献后，关联函数为正并且呈指数衰减。 从部分淬火关联函数得到的标量介子质量1.51(19) GeV与动力学结果一致，并且误差范围明显更小。 显示英文摘要

摘要： This is an exploratory study of the lightest non-singlet scalar $q\bar q$ state on the lattice with two dynamical quarks. Domain Wall fermions are used for both sea and valence quarks on a 16^3*32 lattice with an inverse lattice spacing of 1.7 GeV. We extract the scalar meson mass 1.58(34) GeV from the exponential time-dependence of the dynamical correlators with $m_{val}=m_{sea}$ and N_f=2. Since this statistical error-bar from dynamical correlators is rather large, we analyze also the partially quenched lattice correlators with $m_{val}$ not equal $m_{sea}$. They are positive for $m_{val}>=m_{sea}$ and negative for $m_{val}<m_{sea}$. In order to understand this striking effect of partial quenching, we derive the scalar correlator within the Partially Quenched ChPT and find it describes lattice correlators well. The leading unphysical contribution in Partially Quenched ChPT comes from the exchange of the two pseudoscalar fields and is also positive for $m_{val}>=m_{sea}$ and negative for $m_{val}<m_{sea}$ at large t. After the subtraction of this unphysical contribution from the partially quenched lattice correlators, the correlators are positive and exponentially falling. The resulting scalar meson mass 1.51(19) GeV from the partially quenched correlators is consistent with the dynamical result and has appreciably smaller error-bar.