Search

We present a leptogenesis scenario associated with inflationary models involving non-Abelian gauge fields within the standard model (SM) of particle physics. We show that this class of inflationary models generates intrinsic birefringent gravitational waves that following Alexander, Peskin, and Sheikh-Jabbari [Phys. Rev. Lett. 96, 081301 (2006)], through the gravitational chiral anomaly in the SM, can naturally create a net lepton number density. The CP-violating interaction is produced by tensor fluctuations of the gauge field, while the efficiency of this process is determined by the effective background value of the gauge field. We demonstrate that this mechanism can create the observed value of baryon to photon number density in a natural range of parameters of these models. [ABSTRACT FROM AUTHOR]

We present an exhaustive analysis on the background inflationary solutions of the chromo-natural model. We show that starting from an arbitrary axion field value xo ε (0, f π), it is possible to have slowroll inflation with enough number of e-folds and determine the allowed region of the parameters corresponding to each xo value. Having the available parameter space, we then study the behavior of the solutions with respect to the initial value of the axion field [ABSTRACT FROM AUTHOR]

We introduce an axion-inflation model embedded in the left-right symmetric extension of the Standard Model in which WR is coupled to the axion. This model merges three milestones of modern cosmology, i.e., inflation, cold dark matter, and baryon asymmetry. Thus, it can naturally explain the observed coincidences among cosmological parameters, i.e., ηB ≈ Pζ and ΩDM ≃ 5ΩB. The source of asymmetry is spontaneous CP violation in the physics of inflation, and the lightest right-handed neutrino is the cold dark matter candidate with mass mN1 ∼ 1 GeV. The introduced mechanism does not rely on the largeness of the unconstrained CP-violating phases in the neutrino sector or fine-tuned masses for the heaviest right-handed neutrinos. It has two unknown fundamental scales, i.e., scale of inflation Λinf = √HMPl and left-right symmetry breaking ΛF. Sufficient matter asymmetry demands that Λinf ≈ ΛF. Baryon asymmetry and dark matter today are remnants of a pure quantum effect (chiral anomaly) in inflation, which, thanks to flavor effects, has been memorized by cosmic evolution. [ABSTRACT FROM AUTHOR]

SU(2) gauge fields and axions can have a stable, isotropic and homogeneous configuration during inflation. However, couplings to other matter species lead to particle production, which in turn induces backreaction on and destabilization of the non-Abelian and axion background. In this paper, we first study the particle production by a SU(2) gauge field coupled to a massive Dirac doublet. To carry out this calculation we have made two technical improvements compared to what has been done in the literature. First, we apply the antisymmetrization of the operators to treat particles and antiparticles on equal footing; second, to deal with the UV divergences, we apply instantaneous subtraction. We find that the backreaction of produced fermions on the SU(2) background is negligible for model parameters of observational interest. Next, we consider production of fermions due to coupling to the axion. The tree-level backreaction on the gauge fields, as well as on the axion, is vanishingly small. We also provide an estimate for the loop effects. [ABSTRACT FROM AUTHOR]

We present an exhaustive analysis on the background inflationary solutions of the chromo-natural model. We show that starting from an arbitrary axion field value 0∈(0,fπ), it is possible to have slow-roll inflation with enough number of e-folds and determine the allowed region of the parameters corresponding to each 0 value. Having the available parameter space, we then study the behavior of the solutions with respect to the initial value of the axion field. [ABSTRACT FROM AUTHOR]