$\theta$-dependence of QCD at Finite Isospin Density
  We probe the $\theta$-dependence of QCD at finite isospin chemical potential $\mu_I$ using the effective chiral Lagrangian approach. The phase diagram in the $\theta$, $\mu_I$ plane is constructed and described in detail in terms of chiral and pion condensates. The physics at $\theta ~ \pi$ is investigated in both the normal and superfluid phase. Finally, the behaviour of the gluon condensate at finite $\mu_I$ is computed. 
Max A. Metlitski and Ariel R. Zhitnitsky