Accelerating Cosmologies and Inflation From M/Superstring Theories

Abstract

We review the recent developments in obtaining accelerating cosmologies and/or inflation from higher-dimensional gravitational theories, in particular superstring theories in ten dimensions and M-theory in eleven dimensions. We first discuss why it is difficult to obtain inflationary behavior in the effective low-energy theories of superstring/M-theory, i. e. supergravity theories. We then summarize interesting solutions including S-branes that give rise to accelerating cosmologies and inflationary solutions in M-theory with higher order corrections. Other approaches to inflation in the string context are also briefly discussed.

MAXIMAL SUPERGRAVITIES AND THE E10 COSET MODEL

“…This solution is known to have phases of accelerated and decelerated expansion, 55,56 and is identical in form to the SM2-brane solution, see Ref. 57 and references therein. Similar BPS solutions and their properties in the context of E 11 were discussed earlier in Refs.…”

A new handle on de sitter compactifications

“…3 As in flux compactifications on spheres (familiar in recent years for their role in the AdS/CFT correspondence), the tadpoles arising from the curvature in the geometry are cancelled by forces introduced by other ingredients arising at higher orders in the expansion 1 Many important works have appeared recently in the area of moduli stabilization and the discretuum, including for example [4 -34]. The works for example [35,36] considered compactification on hyperbolic spaces, and the work [37] considered compactifications of field theories on Riemann surfaces.…”

Group theoretical interpretation of the modified gravity in de Sitter space

“…Among alternative proposed models the so-called extended theory of gravitation and, in particular, the gravity theories stem from nonlinear actions or higher-order theories of gravity have provided interesting results [7][8][9][10][11][12][13][14][15][16][17][18][19]. These models are based on gravitational…”