2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/27222We investigate whether or not Kondo insulators undergo a magnetic field induced metal-insulator transition in one dimension at half filling using both a density matrix formulation of the numerical renormalization group and a new analytical approach. Contrary to expectations, the quasiparticle gap never vanishes at any field and no metal-insulator transition is found. We discuss generalizing our result to three dimensions and to the asymmetric Anderson lattice. Our result is consistent with recent experiments.4 pages (using REVTEX), 2 figures in postscript. Submitted to Physical Review LettersCondensed Mattertext