Where new gravitational physics comes from: M-theory?

TL;DR

This paper proposes that modifications to General Relativity arising from string/M-theory compactifications could explain cosmic acceleration without dark energy, linking fundamental physics to cosmological observations.

Contribution

It demonstrates that hyperbolic compactifications of string/M-theory naturally produce gravity modifications with negative curvature terms, potentially explaining cosmic acceleration.

Findings

Effective 4D gravity includes negative power curvature terms

Hyperbolic compactifications lead to modified gravity models

Models may eliminate the need for dark energy

Abstract

It is suggested \cite{CDTT} that current cosmic acceleration arises due to modification of General Relativity by the terms with negative powers of curvature. We show that time-dependent (hyperbolic) compactifications of string/M-theory lead to the effective 4d gravity which naturally contains such terms. The same may be achieved in braneworld by the proper choice of the boundary action. Hence, such a model which seems to eliminate the need for dark energy may have the origin in M-theory.