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

We discuss possible destinations from the chromomagnetic instability in color superconductors with Fermi surface mismatch deltaµ. In the two-flavor superconducting (2SC) phase we calculate the effective potential for color vector potentials A_alpha which are interpreted as the net momenta q of pairing in the Larkin-Ovchinnikov-Fulde-Ferrel (LOFF) phase. When 1/sqrt(2)<deltaµ/Delta<1 where Delta 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 deltaµ/Delta=1/sqrt(2) the magnitude of q continuously increases from zero as the effective potential has negative larger curvature at vanishing A_alpha that is the Meissner mass squared. In the gapless 2SC (g2SC) phase, in contrast, the effective potential has a minimum at gA_alpha~deltaµ~Delta 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~deltaµ.

©2006 The American Physical Society