T-duality and dimensional reduction of S-brane solutions

TL;DR

This paper investigates how T-duality and dimensional reduction apply to spacelike brane solutions in supergravity, highlighting conditions under which these procedures are well-defined and emphasizing the importance of static dilaton fields for their validity.

Contribution

It clarifies the conditions for consistent dimensional reduction and T-duality in spacelike brane solutions, emphasizing the role of static dilaton expectation values.

Findings

Dimensional reduction requires static dimensions for well-definedness.

T-duality is ill-defined when dilaton depends on time.

Supergravity solutions are valid low-energy limits only with time-independent dilaton values.

Abstract

We studied dimensional reduction and T-duality in spacelike brane solutions of 10 or 11 dimensional supergravity, including spacelike counterparts of wave and monopole solutions. Dimensional reduction is well-defined if, and only if, the solutions possess static dimensions. However, T-duality is ill-defined for some of these solutions where dilaton expectation values depend on time. This led us to conclude that supergravity solutions should be regarded as low-energy solutions of superstring theory only if dilaton expectation values are independent of time.