Characterizing the Larkin-Ovchinnikov-Fulde-Ferrel phase induced by the chromomagnetic instability

Abstract

We discuss possible destinations from the chromomagnetic instability in color superconductors with Fermi surface mismatch $δμ$. In the two-flavor superconducting (2SC) phase we calculate the effective potential for color vector potentials $A_α$ which are interpreted as the net momenta $q$ of pairing in the Larkin-Ovchinnikov-Fulde-Ferrel (LOFF) phase. When $1/\sqrt{2}<δμ/Δ<1$ where $Δ$ is the gap energy, the effective potential suggests that the instability leads to a LOFF-like state which is characterized by color-rotated phase oscillations with small $q$. In the vicinity of $δμ/Δ=1/\sqrt{2}$ the magnitude of $q$ continuously increases from zero as the effective potential has negative larger curvature at vanishing $A_α$ that is the Meissner mass squared. In the gapless 2SC (g2SC) phase, in contrast, the effective potential has a minimum at $gA_α\simδμ\simΔ$ even when the negative Meissner mass squared is infinitesimally small. Our results imply that the chromomagnetic instability found in the gapless phase drives the system toward the LOFF state with $q\simδμ$.