Intermediate inflation with non-canonical scalar field in the low anisotropy Universe

Abstract

The behavior of a non-canonical scalar field within an anisotropic Bianchi type I, spatially homogeneous Universe in the framework of the intermediate inflation will be studied. It will be examined on the condition that both the anisotropy and non-canonical sources come together if there is any improvement in compatibility with the observational data originated from Planck 2015. Based on this investigation, it can be observed that automatically a steep potential which can manage inflation in a better way will be obtained. Additionally, as a common procedure for an inflationary study, we shall try to calculate the related inflationary observables such as the amplitude of the scalar perturbations, scalar and tensor spectral indices, tensor-to-scalar ratio, the running spectral index and the number of e-folds. As an exciting part of our results, we will find that our model has a good consistency compared to data resulting from CMB and different Planck results. To justify our claims, the well-known canonical inflationary scenario in an anisotropic Bianchi type I Universe will also be evaluated.

Inflation with non-canonical scalar fields revisited

“…Among their many advantages, non-canonical scalars satisfy in a more efficient way the slow-roll conditions of inflation, since the additional effective friction terms in the equations of motion of the inflaton slow down the scalar field for potentials which would otherwise be too steep. Hence, the resulting tensor-to-scalar ratio is significantly reduced [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. Moreover, models with non-canonical kinetic terms often allow for the kinetic term to play the role of dark matter and the potential terms to generate dark energy and inflation [50][51][52][53].…”

Cosmological aspects of unified theories

“…From the above analysis we deduce that non-canonical kinetic terms combined with deformed-steepness potentials can provide inflationary predictions in very good agreement with observations, compared to simple non-canonical models [68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85] as well as to canonical models with deformed-steepness potentials [96][97][98][99][100][101][102][103]. An additional significant advantage is that the above combination allows good predictions without the need to use unnaturally large values for α or n, or unnaturally tuned values for the non-canonicality and potential scales M and V 0 , as well as for the potential exponent λ.…”

“…Among their many advantages, non-canonical scalars satisfy in a more natural way the slow-roll conditions of inflation, since the additional effective friction terms in the equations of motion of the inflaton slow down the scalar field for potentials which would otherwise be too steep. Hence, the resulting tensor-to-scalar ratio is significantly reduced [68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85]. Moreover, models with non-canonical kinetic terms often allow for the kinetic term to play the role of dark matter and the potential terms to generate dark energy and inflation [86][87][88][89].…”

Warm inflation with non-comoving scalar field and radiation fluid

“…To find an explicit expression of the above equations, and without losing any generality, one can assume that a 3 (t) = a λ i (t), i = 1, 2, in which λ is a constant whose value should be obtained from the comparison with the observational data [170][171][172]. Since the scale factor for the x direction is the same as for the y one, so that a 1 (t) = a 2 (t), consequently, from Eqs.…”

“…To determine α we can use the generalized de Sitter scale factor, the so-called intermediate scale factor [168][169][170][171][172], and a power-law expression of the scale factor. As the first example we can consider a i (t) = a 0i e γ t n , while for the power-law case we will introduce the scale factor asā i (t) =ā 0i t m (see [173] and the references therein).…”