BPS Saturation from Null Reduction

TL;DR

This paper demonstrates that null reductions of higher-dimensional pure gravity solutions inherently satisfy the BPS bound under certain conditions, linking higher-dimensional gravity to lower-dimensional BPS states.

Contribution

It establishes a connection between null reduction of higher-dimensional gravity and BPS saturation, providing conditions under which the bound is saturated.

Findings

Null reduction solutions must saturate the BPS bound.

The BPS saturation is consistent with the field equations.

Applicable to asymptotically Minkowskian solutions in $d \\ge 4$."

Abstract

We show that any $d$-dimensional strictly stationary, asymptotically Minkowskian solution $(d\ge 4)$ of a null reduction of $d+1$-dimensional pure gravity must saturate the BPS bound provided that the KK vector field can be identified appropriately. We also argue that it is consistent with the field equations.