Particle creation and bulk viscosity in Bianchi-I universe in Saez–Ballester theory with different deceleration parameters

Abstract

In Saez–Ballester gravitational theory, we studied the role of particle creation and bulk viscosity in the evolution of a spatially homogeneous and anisotropic Bianchi type I universe. We treated particle creation and bulk viscosity as two distinct irreversible processes, and we modified the energy momentum tensor to account for viscous and particle creation pressures. We employed constant and variable deceleration parameters to obtain average scale factor solutions for the Bianchi type I model. The use of constant deceleration parameter resulted in two unique scale factor solutions that led to singular and non-singular natures of the universe with power-law and exponential laws, respectively. Furthermore, the variable deceleration parameter yielded a de Sitter like solution representing a non-singular universe. We also explored the temporal evolution of the bulk viscosity coefficient in Eckart’s theory, truncated theory, and full causal theory for all three models.