Order ρ²Corrections to Randall-Sundrum I Cosmology

Abstract

We derive the corrections to the Friedmann equation of order ρ 2 in the RandallSundrum (RS) model, where two 3-branes bound a slice of five-dimensional Anti-deSitter space. The effects of radion stabilization by the Goldberger-Wise mechanism are taken into account. Surprisingly, we find that an inflaton on either brane will experience no order ρ 2 corrections in the Hubble rate H due to its own energy density, although an observer on the opposite brane does see such a correction. Thus there is no enhancement of the slow-roll condition unless inflation is simultaneously driven by inflatons on both branes. Similarly, during radiation domination, the ρ 2 correction to H on a given brane vanish unless there is nonvanishing energy density on the opposite brane. During the electroweak phase transition the correction can be large, but is has the wrong sign for causing sphalerons to go out of thermal equilibrium, so it cannot help electroweak baryogenesis. We discuss the differences between our results and exact solutions in RS-II cosmology.

CMB anisotropies in the presence of extra dimensions

“…This behaviour was observed in one-brane scenarios [19] but was shown to hold in two-brane scenarios as well (see in particular [20] and [21]). However, for densities much less than the brane tension, the usual law H ∝ √ ρ can be recovered, albeit with some corrections coming from the scalar fields associated with the bulk dynamics.…”

Scalar kinks in warped extra dimensions

“…(32) and (34) to form a well-posed problem. Note that the above boundary value problem consists of a system of coupled nonlinear differential equations.…”

“…The possibility of extra spatial dimensions [1,2], hidden from our current experiments and observations through compactification or warping, has opened up a wealth of options for particle physics model building [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and has allowed entirely new approaches for addressing cosmological problems [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. In many implementations, standard model (SM) fields can be confined to a submanifold, or brane, while in others they populate the entire extradimensional space.…”

Brane Worlds Cosmology

“…Moreover the result depends upon whether the expansion of the universe is measured at the Planck brane (y = 0) or the TeV brane (y = 1). At the TeV brane, the leading correction was found to be [9] …”