I=1/2 low-lying mesons in lattice QCD

Using conventional constituent-quark model, $I=1/2$ scalar $\kappa$, vector $K^\ast(892)$, and axial vector $K_1$ mesons are studied in the asqtad-improved staggered fermion with the wall-source and point-sink interpolators. The mass ratio of $m_{\kappa}/m_{K^\ast(892)}$ is numerically confirmed to vary apparently with quark mass, and the experimental ordering $m_{K^\ast(892)} > m_{\kappa}$ is elegantly hold when the light $u/d$ quark masses are sufficiently small, while the valence strange quarks are fixed to its physical values. We also get reasonable signals for $K_1$ meson suggested by SCALAR Collaboration from lattice QCD. The computations are conducted with the MILC $N_f=3$ flavor gauge configurations at three lattice spacings: $a\approx 0.15$, $0.12$, and $0.09$ fm.