2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/201383We give a simple general extension to all free bosonic and fermionic massless gauge fields of a recent proof that spin 2 is duality invariant in flat space. We also discuss its validity in (A)dS backgrounds and the relevance of supersymmetry.3 pagesHigh Energy Physics - TheoryGeneral Relativity and Quantum Cosmologytext