Brane inflation revisited after WMAP five-year results

Abstract

In this paper, we revisit brane inflation models with the WMAP five-year results.The WMAP five-year data favor a red-tilted power spectrum of primordial fluctuations at the level of two standard deviations, which is the same as the WMAP three-year result qualitatively, but quantitatively the spectral index is slightly greater than the three-year value. This result can bring impacts on brane inflation models.According to the WMAP five-year data, we find that the KKLMMT model can survive at the level of one standard deviation, and the fine-tuning of the parameter β can be alleviated to a certain extent at the level of two standard deviations.

Confronting brane inflation with Planck and pre-Planck data

“…The prototype of the brane inflation model discussed above is not a realistic model, because the distance between the brane and the antibrane would be larger than the size of the extra-dimensional space if the inflaton is slowly rolling in this scenario [20,23]. It indicates that this model is not really reliable from the viewpoint of theory itself.…”

“…The parameter n has to satisfy n 4 because the transverse dimension has to be less or equal to 6. The e-folding number N e at the horizon exit before the end of inflation is related to the field value as [20,23] N ¼ ½N e M 2 pl n nðn þ 2Þ 1=ðnþ2Þ :…”

“…When the brane and antibrane collide and annihilate, the inflation ends and the hot big-bang epoch is initiated. The annihilation of the brane and antibrane makes the universe settle down to the string vacuum state that describes our Universe [19,20]. For extensive studies on the KKLMMT model and other types of slow-roll brane inflation models, see Refs.…”

“…For extensive studies on the KKLMMT model and other types of slow-roll brane inflation models, see Refs. [11,[20][21][22][23][24][25][26][27].…”

Non-minimal warm inflation and perturbations on the warped DGP brane with modified induced gravity

“…For an inflationary model driven by just one scalar field, the running of the spectral index constraint by the WMAP5 + SDSS + SNIa combined data is α s ≡ d n s d ln k = −0.032 +0.021 −0.020 , with 1σ CL (see for instance [81] and references therein). In our case, we see that dissipative effects, modified induced gravity and the non-minimal coupling of the scalar field and induced gravity have the potential to produce a variety of spectra ranging between red and blue (see [5,8,28,37,62,71,72] for realization of these spectral index in different scenarios).…”