Two-field Models of Dark Energy with Equation of State Across -1
  In this paper, we study the possibility of building two-field models of dark energy with equation of state across -1. Specifically we will consider two classes of models: one consists of two scalar fields (Quintessence+Phantom) and another includes one scalar (Phantom) and one spinor field (Neutrino). Our studies indicate to some extent that two-field models give rise to a simple realization of the dynamical dark energy model with the equation of state across $w = -1$. 
Xiao-fei Zhang, Hong Li, Yun-Song Piao and Xinmin Zhang