SPINOR FIELD IN BIANCHI TYPE-II UNIVERSE

Within the scope of Bianchi type-II cosmological model we have studied the role of spinor field in the evolution of the Universe. It is found that in this case the components of energy-momentum tensor of spinor field along the principal axis are different, i.e. T11 ≠ T22 ≠ T33, even in absence of spinor field nonlinearity. The presence of nontrivial non-diagonal components of energy-momentum tensor of the spinor field imposes severe restrictions both on geometry of space-time and on the spinor field itself. Depending on the choice of f(x3) the space-time might be either locally rotationally symmetric or isotropic. In this paper we considered the Bianchi type-II space-time both for a trivial and nontrivial b. It was found that while a positive λ1 in case of f′ ≠ 0 gives rise to oscillatory mode of evolution, in case of f′ = 0 it leads to accelerated mode of expansion. © 2023, Publishing House of the Romanian Academy. All rights reserved.