Gauss–Bonnet braneworld and WMAP three year results

Abstract

We compare predictions for the spectral index and tensor-scalar ratio in models of patch inflation with the WMAP three year data. There are three cases of these models of inflation, which arise in the Gauss-Bonnet braneworld scenario: Gauss-Bonnet (GB), Randall-Sundrum (RS), and 4D general relativity (GR). We consider the large-field potential V ∝ φ p in both commutative and noncommutative spacetimes, and find that in the cases of the GB and GR patch cosmologies, the quadratic potential is observationally favored, while the quartic potential is ruled out in most patches. Strong noncommutative inflation is excluded in all cases because it leads to a blue-tilted scalar spectral index.

Strong Planck constraints on braneworld and non-commutative inflation

“…The RS braneworld was compared against WMAP3 [61,62] and WMAP5 data [63]: the potentials with small-field variations turned out to be favored [62] and the quartic potential excluded [61]. The quartic potential was also excluded in the GB braneworld by WMAP3 data [61]. Planck data were recently used also in [64], but on a DGP brane model different from the present ones.…”

“…Planck data were recently used also in [64], but on a DGP brane model different from the present ones. Reference [61] also studied non-commutative inflation in the IR limit, using the patch formalism of [40] and WMAP3 data, which led to the exclusion of quadratic and quartic potentials in the σ = 6 model. These potentials have been ruled out also by Planck data, but only in the UV mild non-commutative regime [65].…”

Intermediate inflation in Gauss–Bonnet brane world

“…For modes with a wavelength much larger than the horizon (k ≪ aH), where k is the comoving wave number. The scalar q-spectral index is given by [22], and in our case becomes…”

“…This kind of theory has been applied to possible resolution of the initial singularity problem [13], to the study of Black-Hole solutions [14], accelerated cosmological solutions [15], among others (see Refs. [16][17][18][19][20][21][22]). In particular, very recently, it has been found that for a dark energy model the GB interaction in four dimensions with a dynamical dilatonic scalar field coupling leads to a solution of the form a = exp At f [23], where the universe starts evolving with a decelerated exponential expansion.…”

Closed inflationary universe in patch cosmology

“…In fact, all versions of string theory (except type II) in 10 dimensions include this term. Therefore, it could be interesting to make study the effects of the Gauss-Bonnet term on inflationary brane world models [18][19][20][21][22][23][24].…”