Nonlinear Spinor Fields in Bianchi type-VI spacetime

TL;DR

This paper investigates how nonlinear spinor fields influence the evolution of the Universe within Bianchi type-VI spacetime, revealing restrictions on the fields and metric, and showing potential for late-time acceleration or oscillatory behavior.

Contribution

It demonstrates that in Bianchi type-VI spacetime, spinor fields with nonlinearity and mass terms are not eliminated by geometric restrictions, unlike in other Bianchi models, and explores their impact on cosmic evolution.

Findings

Spinor field energy-momentum tensor has non-diagonal components due to affine connections.

Restrictions on spinor or metric functions arise from non-diagonal energy-momentum components.

The model can produce late-time acceleration or oscillations depending on self-coupling sign.

Abstract

Within the scope of Bianchi type-VI cosmological model we study the role of spinor field in the evolution of the Universe. It is found that due to the spinor affine connections the energy-momentum tensor of the spinor field possesses non-diagonal components. The non-triviality of non-diagonal components of the energy-momentum tensor imposes some severe restrictions either on the spinor field or on the metric functions or on both of them. But unlike in cases of Bianchi type-I or $VI_0$, in case of Bianchi type-VI model it does not lead to the elimination of spinor field nonlinearity or mass term in the spinor field Lagrangian. It is also found that depending on the sign of self-coupling constant the model can give rise to late time acceleration or generate oscillatory mode of evolution.