Inflation from fermions with curvature-dependent mass

A model of inflation realization driven by fermions with curvature-dependent mass is studied. Such a term is derived from the covariant canonical gauge theory of gravity (CCGG) incorporating Dirac fermions. We obtain an initial de Sitter phase followed by a successful exit, and moreover we acquire the subsequent thermal history, with an effective matter era, followed finally by a dark-energy epoch. This behavior is a result of the effective “weakening” of gravity at early times, due to the increased curvature-dependent fermion mass. Investigating the scenario at the perturbation level, using the correct coupling parameter, the scalar spectral index and tensor-to-scalar ratio are obtained in agreement with Planck observations. Moreover the big bang nucleosynthesis constraints are satisfied too. The efficiency of inflation from fermions with curvature-dependent mass, at both the background and perturbation level, reveals the capabilities of the scenario and makes it a good candidate for the description of nature.

Figure 1

The effective potential from Eq. (30).

Figure 2

The evolution of the normalized effective Newton’s constant (upper graph), and of the normalized curvature-dependent fermion mass (lower graph), for various values of $\tilde{\xi }$, for ${\rho }_{f0}=0.3$ and $\mathrm{\Lambda }=0.7$, in units where ${\kappa }^2=1$.