Lattice QCD Study of Hadronic Matrix Elements by Numerical Simulations

用大尺度格子QCD模拟计算了K介子袋参数B_K和B介子衰变常数f_B和f_K等重要的强子矩阵元。<BS>为了估计连续介质理论中矩阵元的值，我们系统地研究了有限格子间距引起的各种离散误差的影响。取连续极限后，得到B_K=0.628（42），f_B=173（4）MeV，f_K <BS>=199（3）MeV。我们还进行了格点QCD模拟，计算了夸克质量、强子谱、静态夸克势和K^+-pi^+ pi ^0衰变振幅，并研究了2味和3味QCD有限温度手征相变的性质。

Large scale lattice QCD simulations have been made to calculate phenomenologically important hadronic matrix elements such as the K meson bag parameter B_K and the B meson decay constant f_B and f_<BS>, To estimate the values of the matrix elements in the continuum theory, we systematically study the effects of various discretization errors caused by finite lattice spacing. After taking continuum limit, we obtain B_K=0.628(42), f_B=173(4)MeV and f_<BS>=199(3) MeV.Lattice QCD simulations have also been made to calculate quark masses, hadron spectrum, static quark potential and K^+-pi^+pi^0 decay amplitude and to study the nature of the finite temperature chiral phase transition of 2 and 3 flavors QCD.