Cosmology in Nonlinear Born-Infeld Scalar Field Theory With Negative Potentials

The cosmological evolution in Nonlinear Born-Infeld(hereafter NLBI) scalar field theory with negative potentials was investigated. The cosmological solutions in some important evolutive epoches were obtained. The different evolutional behaviors between NLBI and linear(canonical) scalar field theory have been presented. A notable characteristic is that NLBI scalar field behaves as ordinary matter nearly the singularity while the linear scalar field behaves as "stiff" matter. We find that in order to accommodate current observational accelerating expanding universe the value of potential parameters $|m|$ and $|V_0|$ must have an {\it upper bound}. We compare different cosmological evolutions for different potential parameters $m, V_0$.