Brane gases in the early Universe

By S. Alexander, Robert Brandenberger, D. Easson. 2000

206 citations recorded by the source corpus.

Over the past decade it has become clear that fundamental strings are not the only fundamental degrees of freedom in string theory. D-branes are also part of the spectrum of fundamental states. In this paper we explore some possible effects of D-branes on early Universe string cosmology, starting with two key assumptions: firstly that the initial state of the Universe corresponded to a dense, hot gas in which all degrees of freedom were in thermal equilibrium, and secondly that the topology of the background space admits one-cycles. We argue by t duality that in this context the cosmological singularities are not present. We derive the equation of state of the brane gases and apply the results to suggest that, in an expanding background, the winding modes of fundamental strings will play the most important role at late times. In particular, we argue that the string winding modes will only allow four space-time dimensions to become large. The presence of brane winding modes with p>1 may lead to a hierarchy in the sizes of the extra dimensions.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/510b74fc5a36a2d33ab70c05f14b9750901490f6

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Citations in the corpus

String gas cosmology and structure formation (2006, background): “String gas cosmology (SGC) [1, 2] (see also [3] for early work, [4, 5] for recent overviews, and [6] for a critical review) is an approach to string cosmology, based on adding minimal but crucial inputs from string theory, namely new degrees of freedom - string oscillatory and winding modes - and ne”
Chern-Simons Modified General Relativity (2009, background): “In fact, there are other models that suggest the CS correction could be enhanced, due to non-perturbative instanton corrections [5], interactions with fermions [6], large intrinsic curvatures [7] or small string couplings at late times [8,9,10,11,12,13,14,15,16,17].”
D‐branes in Standard Model building, gravity and cosmology (2003, background): “They cannot fluctuate, (10)A reduced version of a universe containing branes has been advocated in [42].”
Modified Gravity and Cosmology (2011, background): “Note that this result is not spoilt by the inclusion of branes wrapping compact directions, as these happen to fall out of equilibrium before the strings [21].”
String gas cosmology (2005, background): “…focusing on cosmic strings in (Sakellariadou, 1996) (see also (Cleaver and Rosenthal, 1995) ) and later extended to the case of branes in (Alexander et al., 2000), where it was argued that the strings remain the important objects, since branes fall out of equilibrium sooner than strings,…”
On the Spectrum of Fluctuations in an Effective Field Theory of the Ekpyrotic Universe (2001, background): “state, with all degrees of freedom, including winding strings [23] and branes [25], excited.”