2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/219324Using a recently constructed M5-brane world-volume action, we demonstrate that wrapping the M5-brane on K3 gives the heterotic string in seven dimensions. To facilitate the comparison, a new version of the world-sheet action for the Narain-compactified heterotic string, with manifest T duality invariance, is formulated.14 pages, latex, no figures; an error has been correctedHigh Energy Physics - Theorytext