2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190511It is possible to determine a propapagator for heavy quarks to order 1/m in any covariant gauge, which applies universally to all quarks, by using the gauge technique. The leading behaviour is given by a _0F_2 function and the result is reliable in the infrared limit, accounting for soft-gluon corrections to the quark in internal loops.12 pages, RevTex format. Typographical errors corrected (factors of 2 in eqs 25 and 26)High Energy Physics - Phenomenologytext