On the Exotic Phases of M-theory

TL;DR

This paper explores new phases of M-theory through generalized dualities, analyzing brane solutions, intersection rules, and entropy behavior, revealing potential non-conservation of entropy under certain dualities.

Contribution

It introduces a framework for understanding brane configurations in new M-theory phases and examines their implications for black hole entropy and duality properties.

Findings

Intersection rules for branes in new M-theory phases

Conditions for regular extremal black holes after compactification

Entropy may vary with the radius of the timelike dimension, indicating non-conservation

Abstract

We study aspects of the new phases of M-theory recently conjectured using generalised dualities such as timelike T-duality. Our focus is on brane solutions. We derive the intersection rules in a general framework and then specialise to the new phases of M-theory. We discuss under which conditions a configuration with several branes leads to a regular extremal black hole under compactification. We point out that the entropy seems not to be constant when the radius of the physical timelike direction is varied. This could be interpreted as a non-conservation of the entropy (and the mass) under at least some of the new dualities.