Big bang nucleosynthesis constraints on universal extra dimensions and varying fundamental constants

Abstract

The successful prediction of light element abundances from Big Bang Nucleosynthesis (BBN) has been a pillar of the standard model of Cosmology. Because many of the relevant reaction rates are sensitive to the values of fundamental constants, such as the fine structure constant and the strong coupling constant, BBN is a useful tool to probe and to put constraints on possible cosmological variations of these constants, which arise naturally from many versions of extra-dimensional theories. In this paper, we study the dependences of fundamental constants on the radion field of the universal extra dimension model, and calculate the effects of such varying constants on BBN. We also discussed the possibility that the discrepancy between BBN and the Wilkinson Microwave Anisotropy Probe (WMAP) data on the baryon-to-photon ratio can be reduced if the volume of the extra dimensions was slightly larger -by O(10 −3 ) -at the BBN era compared to its present value, which would result in smaller gauge couplings at BBN by the same factor.

Varying Constants, Gravitation and Cosmology

“…An analysis of most cosmological data (BBN, CMB, quasar etc..) assuming that the extra-dimension scales as R 0 (1 + ∆t −3/4 ) and R 0 [1+∆](1−cos ω(t−t 0 ) concluded that ∆ has to be smaller tha 10 −16 and 10 −8 respectively [304], while Ref. [328] assumes that gauge fields and matter fields can propagate in the bulk. Ref.…”

Minimal universal extra dimensions inCalcHEP/CompHEP

“…[6][7][8][9][10][11] for the case of two universal extra dimensions). This particular scenario has recently been studied in relation to collider phenomenology [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], indirect low-energy constraints [30][31][32][33][34][35][36][37][38][39][40][41][42][43], dark matter and cosmology [67][68][69][70][71][72][73]. It is therefore of great interest to have an implementation of the Minimal UED model (reviewed below in Section 2) in the most popular general purpose computer programs for collider and astroparticle phenomenology.…”

Brane isotropization in an extra-dimensional Tolman-Bondi universe

“…Of course our model does not directly apply to our 4d Universe. Strong constraints on isotropy during big bang nucleosynthesis should be taken into account [23,24]. Moreover, the dynamics would be certainly changed by the presence of matter on the brane.…”