Consequences of $$f(R)$$ f ( R ) theories of gravity on gravitational leptogenesis

Abstract

f (R)-theories of gravity are reviewed in the framework of the matter-antimatter asymmetry in the Universe. The asymmetry is generated by the gravitational coupling of heavy (Majorana) neutrinos with the Ricci scalar curvature. In order that the mechanism works, a time varying nonzero Ricci curvature is necessary. The latter is provided by f (R) cosmology, whose Lagrangian density is of the form L(R) ∼ f (R). In particular we study the cases f (R) ∼ R + αR n and f (R) ∼ R 1+ǫ . 98.80.Cq

Neutrino Coupling to Cosmological Background: A Review on Gravitational Baryo/Leptogenesis

“…The effects of washed out are avoided by considering the effective (five dimensional) operator violating the lepton number ∆L = 2, as before discussed. Notice that the baryon asymmetry is generated both for[86] n = 2 and n = 2 The case n < 0 is excluded because these f (R) models of gravity are affected by instability problems[7][8][9].…”

Baryo-Leptogenesis induced by modified gravities in the primordial Universe

“…In the last few decades different models of leptogenesis have been developed [1,2,[29][30][31][32][33][34][35]. In the following we will consider a theory that explains lepton asymmetry as a consequence of scalar curvature, similarly as we have proceeded for the gravitational baryogenesis [31,32,35].…”

“…In the last few decades different models of leptogenesis have been developed [1,2,[29][30][31][32][33][34][35]. In the following we will consider a theory that explains lepton asymmetry as a consequence of scalar curvature, similarly as we have proceeded for the gravitational baryogenesis [31,32,35]. In the model [31,32,35] the origin of lepton asymmetry is realized by a new lagrangian in which a coupling between Majorana Neutrinos and Ricci scalar.…”

“…These neutrinos, whose masses are described by the see-saw mechanism [36,37], are main actors in the model of leptogenesis studied hereafter. The above introduced interaction, which violates CP, and that it is even under C, and odd under P, is described by [31,35]:…”

Quantum viewpoint of quadratic f(R) gravity, constraints, vacuum-to-vacuum transition amplitude and particle content

“…, as generalizations of general relativity, from both the classical and the quantum view points. With the hope of compatibility with experimental data, correct Newtonian and post-Newtonian limits, and other consistency requirements, classically (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13]), the interest has been, for example, in developing alternatives to dark energy models in explaining the cosmic acceleration [9]. Quantum mechanically, the nonrenormalizable aspect of perturbative general relativity [14][15][16][17][18] has led, in turn, to introduce counterterms to the Einstein-Hilbert action involving higher-order derivatives, thus necessarily modifying Einstein's theory.…”