Density Induced Quantum Phase Transitions in Triplet Superconductors
  We consider the possibility of quantum phase transitions in the ground state of triplet superconductors where particle density is the tunning parameter. For definiteness, we focus on the case of one band quasi-one-dimensional triplet superconductors but many of our conclusions regarding the nature of the transition are quite general. Within the functional integral formulation, we calculate the electronic compressibility and superfluid density tensor as a function of the particle density for various triplet order parameter symmetries and find that these quantities are non-analytic when a critical value of the particle density is reached. 
R. W. Cherng, C. A. R. S\'a de Melo