Metric and coupling reversal in string theory

TL;DR

This paper explores how reversing the metric and string coupling sign in string theory results in four distinct universes, each with different brane configurations, revealing a novel symmetry structure in string theory landscapes.

Contribution

It introduces a new symmetry involving metric and coupling reversal, leading to four distinct universes with unique brane contents in string theory.

Findings

Four universes with different brane spectra identified

Reversal symmetry connects different string theory configurations

Conventional string theory is one of the four universes

Abstract

Invariance under reversing the sign of the metric G_{MN}(x) and/or the sign of the string coupling field H(x), where <H(x)> = g_s, leads to four possible Universes denoted 1,I,J,K according as (G,H) goes to (G,H), (-G,H), (-G,-H), (G,-H), respectively. Universe 1 is described by conventional string/M theory and contains all M, D, F and NS branes. Universe I contains only D(-1), D3 and D7. Universe J contains only D1, D5, D9 and Type I. Universe K contains only F1 and NS5 of IIB and Heterotic SO(32).