D-brane anti-brane annihilation in an expanding universe

Abstract

The time-varying density of D-branes and anti-D-branes in an expanding universe is calculated. The D-brane anti-brane annihilation rate is shown to be too small to compete with the expansion rate of a FRW type universe and the branes over-close the universe. This brane problem is analogous to the old monopole problem. Interestingly however, it is shown that small dimension D-branes annihilate more slowly than high dimension branes. Hence, an initially brany universe may be filled with only low dimension branes at late times. When combined with an appropriate late inflationary theory this leads to an attractive dynamical way to create a realistic braneworld scenario.

Cosmological creation of D-branes and anti-D-branes

“…This force presumably leads to annihilation of some fraction of the branes in each Hubble volume. In a forthcoming article [46] these, and associated issues are addressed.…”

Linear Cosmological Perturbations in D-brane Gases

“…In [26] it is shown that the interaction rates of strings are not strong enough to sustain thermal equilibrium. Moreover, D-brane anti-D-brane annihilation rate turns out to be small compared to the expansion rate of a FRW universe including the higher dimensional D-branes [12]. Therefore, it seems that the dimensional counting argument of [1] is not sufficient alone for the annihilation process and it is plausible to have surviving branes other than strings or membranes.…”

S-duality in string gas cosmology

“…Note that the energy of the momentum mode should not depend on the tension (15). It should be measured in units of the corresponding angular coordinate parametrizing the circle and thus from (1) and (4) in terms of the string length l s .…”

“…The stringy T-duality invariance is the key symmetry which may resolve the initial big-bang singularity of standard cosmology. Moreover, the naive dependence of the tree level annihilation cross section of winding strings on the number of dimensions might explain the hierarchy between the observed three and internal directions [1] (however it seems there are some caveats in that argument [4][5][6][7] and a more complete understanding of string thermodynamics in an expanding universe is needed). In late times, SGC offers a natural mechanism to stabilize extra dimensions as a result of a balance between negative winding and positive momentum pressures [8].…”