On inflation and axionic dark matter in a scaled gravity

• Published in: European physical journal plus Vol. 139; no. 2; p. 147
• Main Authors: Belhaj, A., Ennadifi, S. E., Lamaaoune, M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 09.02.2024; Springer Nature B.V
• Subjects: Applied and Technical Physics; Atomic; Complex Systems; Condensed Matter Physics; Dark matter; Decay rate; Gravity; Hypothetical particles; Investigations; Mathematical and Computational Physics; Mathematical models; Molecular; Optical and Plasma Physics; Parameters; Physics; Physics and Astronomy; Regular Article; String theory; Theoretical
• ISSN: 2190-5444; 2190-5444
• DOI: 10.1140/epjp/s13360-024-04965-y

Motivated by the modified gravity theories F ( R ) ≠ R and inflationary physics, we first propose and investigate an inflation model in a scaled gravity F ( R ) = R + β R , where β is a dimensionless scaling parameter. The latter is also implemented in a particular potential V ( ϕ ) = M 4 1 - cos ϕ μ β being considered to drive the inflation via a parameter coupling scenario. Using the slow-roll approximations, the gravity scale parameter β is approached with respect to the range of the associated computed cosmological observables n s and r according to the recent Planck and BICEP/Keck data. Then, we discuss the axionic dark matter in the suggested gravity model by considering the case where the inflaton is taken to be identified with an axion-like field ϕ = f a θ with the decay constant f a = μ . Referring to the known data, the underlying inflation scale M is constrained to be much lower than the corresponding axion scale M ≪ f a .