Asymptotic symmetries and charges at null infinity: from low to high spins

¹ Institut für Theoretische Physik, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
² Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Piazza del Viminale 1, I-00184 Roma, Italy
³ Roma Tre University and INFN, Via della Vasca Navale 84, I-00146 Roma, Italy
⁴ Scuola Normale Superiore and INFN, Piazza dei Cavalieri 7, I-56126 Pisa, Italy

^* e-mail: campoleoni@itp.phys.ethz.ch
^** e-mail: dario.francia@roma3.infn.it
^*** e-mail: carlo.heissenberg@sns.it

Published online: 31 October 2018

Abstract

Weinberg’s celebrated factorisation theorem holds for soft quanta of arbitrary integer spin. The same result, for spin one and two, has been rederived assuming that the infinite-dimensional asymptotic symmetry group of Maxwell’s equations and of asymptotically flat spaces leave the S-matrix invariant. For higher spins, on the other hand, no such infinite-dimensional asymptotic symmetries were known and, correspondingly, no a priori derivation of Weinberg’s theorem could be conjectured. In this contribution we review the identification of higher-spin supertranslations and superrotations in D = 4 as well as their connection to Weinberg’s result. While the procedure we follow can be shown to be consistent in any D, no infinite-dimensional enhancement of the asymptotic symmetry group emerges from it in D > 4, thus leaving a number of questions unanswered.