The metric and strong coupling limit of the M5-brane

TL;DR

This paper explores the propagation properties, energy conditions, and strong coupling limit of the M5-brane, revealing a conformally invariant theory with infinite conservation laws at strong coupling.

Contribution

It introduces the analogue of the Boillat metric for the M5-brane and analyzes its properties, including the strong coupling limit and conformal invariance.

Findings

Propagation cone of all 5-brane degrees is determined by the analogue of the Boillat metric.

The energy-momentum tensor satisfies the Dominant Energy Condition.

The strong coupling limit yields a conformally invariant theory with infinite conservation laws.

Abstract

We find the analogue of the Boillat metric of Born-Infeld theory for the M5-brane. We show that it provides the propagation cone of {\sl all} 5-brane degrees. In an arbitrary background field, this cone never lies outside the Einstein cone. An energy momentum tensor for the three-form is defined and shown to satisfy the Dominant Energy Condition. The theory is shown to be well defined for all values of the magnetic field but there is a limiting electric field strength. We consider the strong coupling limit of the M5-brane and show that the corresponding theory is conformally invariant and admits infinitely many conservation laws. On reduction to the Born-Infeld case this agrees with the work of Bia{\l}nicki-Birula.