Expanding and contracting Bianchi type-I cosmologies in f(R, ϕ, X) theory

Kirezli P., ULU DOĞRU M., TAŞER D., Eraslan E.

Modern Physics Letters A, vol.41, no.11, 2026 (SCI-Expanded, Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 41 Issue: 11
  • Publication Date: 2026
  • Doi Number: 10.1142/s0217732326500550
  • Journal Name: Modern Physics Letters A
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, INSPEC, MathSciNet, zbMATH
  • Keywords: Bianchi type-I, f(R, ϕ, X), perfect fluid
  • Çanakkale Onsekiz Mart University Affiliated: Yes

Abstract

f(R; ϕ; X) theory, a combination of scalar-tensor and f(R)-class gravity, is examined for perfect fluids in Bianchi Type-I spacetime. A hybrid model of Starobinsky-like and k-essence is used. Two different forms of solutions are obtained and discussed in Bianchi Type-I cosmology. Effective energy densities, effective pressures and necessary statements of energy conditions for both solutions are analyzed. It is discussed whether f(R; ϕ; X) theory allows expanding or contracting cosmologies for the obtained two forms of Bianchi Type-I spacetime.