2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54278Following a review of the dual description of the non-linear sigma model we investigate the one-loop quadratic divergences. We use the covariant background field method for the general case and apply the results to the important example of $SU(2)$.9 pages, LaTeX2e, no figures, uses axodraw package for Feynman diagrams. Axodraw available via anonymous ftp, ftp://ftp.nikhef.nl/pub/form/axodraw/export DVI version of preprint available via anonymous ftp or WWW; ftp://hep2.phys.soton.ac.uk/pub/preprints/rdsquad.dvi http://wwwhep.phys.soton.ac.uk/hepftp/pub/preprints/rdsquad.dviHigh Energy Physics - TheoryHigh Energy Physics - Phenomenologytext