Abstarct: In this thesis, we present a model of inflation containing the inflaton field and a triplet of U(1) gauge fields. In addition to the local U(1) symmetries, the gauge fields enjoy an internal O(3) symmetry supporting the isotropic FRW solution. With an appropriate coupling between the gauge fields and the inflaton field, the system reaches an attractor regime in which the gauge fields furnish a small constant fraction of the total energy density. We decompose the scalar perturbations into the adiabatic and entropy modes and calculate the contributions of the gauge fields into the curvature perturbations power spectrum. We also calculate the entropy power spectrum and the adiabatic-entropy cross correlation. In addition to the metric tensor perturbations, there are tensor perturbations associated with the gauge field perturbations which also source the primordial gravitational wave perturbations. Moreover, we add the pseudoscalar invariant F_{\mu \nu }^( a )F^~_( a )^{\mu \nu } to our model in order to violate the parity symmetry. Indeed, this term gives us more freedom in tuning the amplitude of the vector fields at the end of the inflation. By decomposing the scalar perturbations into the adiabatic and entropy modes, we calculate the curvature perturbations power spectrum, the entropy power spectrum and the mixed of them. The results show that the parity violating term leads to enhance the cross-correlation between entropy perturbation and the scalar mode.