M-theory preons cannot arise by quotients

Abstract

M-theory preons -- solutions of eleven-dimensional supergravity preserving 31 supersymmetries -- have recently been shown to be locally maximally supersymmetric. This implies that if preons exist they are quotients of maximally supersymmetric solutions. In this paper we show that no such quotients exist. This is achieved by reducing the problem to quotients by cyclic groups in the image of the exponential map, for which there already exists a partial classification, which is completed in the present paper.