Lattice QCD at non-zero isospin chemical potential (2013 ver.)

Systems of non-zero isospin chemical potential are studied from a canonical approach by computing correlation functions with the quantum numbers of N pi(+)\u27s (C-N pi). In order to reduce the number of contractions required in calculating C-N pi for a large N in the Wick\u27s theorem, we constructed a few new algorithms. With these new algorithms, systems with isospin charge up to 72 are investigated on three anisotropic gauge ensembles with a pion mass of 390 MeV, and with lattice spatial extents L similar to 2.0, 2.5, 3.0 fm. The largest isospin density of rho(I) approximate to 9 fm(-3) is achieved in the smallest volume, and the QCD phase diagram is investigated at a fixed low temperature at varying isospin chemical potentials, m(pi) \u3c mu(I) \u3c 4.5 m(pi). By investigating the behaviour of the extracted energy density of the system at different isospin chemical potentials, we numerically identified the conjectured transition to a Bose-Einstein condensation state at mu(I) \u3e= m(pi)