Lee Wick Dark Energy

We consider the cosmological application of Lee-Wick theory where a field has a higher derivative kinetic operators. The higher derivative term can be eliminated by introducing a set of auxiliary fields. We investigate the cosmological evolutions of these fields as a candidate of dark energy. This model has the same structure as so called “quintom’ model except the form of potentials and the sign of the slope of the potentials. This model can give the stable late time phantom dominated scaling solution (ωDE < −1) or tracking attractors (ωDE = 0) depending on the choice of the slopes of the potential. In order to be a viable dark energy candidate, the present energy density contrast of dark energy (Ω (0) DE) should be close to an observed value (0.73) at the same time. However, a simple toy model of the theory can not satisfy both ω (0) DE ≃ −1 and Ω (0) DE = 0.73. This is also true for any quintom model in literatures unless we suffer from the fine tuning problem. We may need to consider more general potentials to get the realistic model which fits to the current observations.