de Sitter space from M-theory?

TL;DR

MM-theory is proposed, a massive extension of eleven-dimensional supergravity that introduces a conformal spin connection to realize de Sitter vacua, addressing long-standing no-go results in M-theory. The authors demonstrate explicit de Sitter solutions in ten and eleven dimensions via compactifications such as $M_{10}\times S^1$ with $k=m dy$ and direct-product ansatze $dS_D \times S^{(10-D)} \times S^1$ that lift to eleven dimensions, yielding a cosmological constant $\Lambda=576 m^2 e^{-2\phi}$. They argue no-go theorems are evaded because MM-theory lacks a conventional action and the Weyl-like structure intermingles supersymmetry with conformal transformations, so there is no globally conserved supercharge. The work also shows de Sitter can occur on eight-brane worldvolumes via a dualized ten-form $F_{10}$, leading to a domain-wall picture and a truncated action, suggesting a natural inflationary scenario within a supersymmetric but nonstandard moduli sector.

Abstract

In this note we study a massive IIA supergravity theory obtained in hep-th/9707139 by compactification of M-theory. We point out that de Sitter space in arbitrary dimensions arises naturally as the vacuum of this theory. This explicitly shows how de Sitter space can be embedded into eleven-dimensional supergravity. In addition we discuss the novel way in which this theory avoids various `no-go theorems' which assert that de Sitter space is not a consistent vacua of eleven-dimensional supergravity theory. We also point out that the eight-branes of this theory, which couple electrically to the ten-form, can sweep out de Sitter world-volumes.