Statefinder Diagnostic for Born--Infeld Type Dark Energy Model

Using a new method cafled the statefinder diagnostics which can make one dark energy model differ from the others, we investigate the dynamics of Born-Infeld （B-I） type dark energy model. The evolution trajectory of B-I type dark energy with Mexican hat potential model with respect to e-folding time N is shown in the r（s） diagram. When the parameter of noncanonical kinetic energy term η→0 or kinetic energy φ^2 →0, the B-I type dark energy （K-essence） model reduces to the quintessence model or the ACDM model corresponding to the statefinder pair （r, s） = {1, 0} respectively. As a result, the evolution trajectory of our model in the r（s） diagram in Mexican hat potential is quite different from those of other dark energy models. The current values of parameters Ωφ and wφ in this model meet the latest observations WMAP5 well.     

Euclidean non-vacuum wormholes in Brans－Dicke theory

The Brans－Dicke theory is investigated in which the Pauli metric is identified to be a physical spacetime metric. The solutions of a wormhole are obtained in Brans－Dicke theory with a relativistic radiation field for ω>-3/2. However, it is found that one cannot construct a wormhole in the presence of a 3-form axion field.