K-π interaction in finite volume and the K^* resonance

Firstly, the K-π interaction in P-wave in a finite volume using the chiral unitary approach was studied, to find an efficient strategy to obtain K-π phase shifts and thus the K^* meson properties from energy levels could be obtained in lattice calculations. This method has been applied to provide K-π shifts in infinite space very successfully. Secondly, the energy levels, which are functions of the cubic box size and the pion mass, were evaluated, and the K-π phase shifts were evaluated based on the physical properties of K^* meson. Finally, in order to compare with the lattice quantum chromodynamics (QCD) results, non-physical pion masses were adopted to calculate energy levels of the K^* meson. Comparison shows that results from approach mentioned above agree well with those from lattice QCD: using pion mass 266 MeV, we obtain two energy levels, 924.0 MeV and 1 483.0 MeV respectively, which accord well with the lattice QCD results, 915.6 MeV and 1 522.3 MeV respectively.