2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/40429Recent results for charm quark mass effects in perturbative bottom quark mass determinations from $Υ$ mesons are reviewed. The connection between the behavior of light quark mass corrections and the infrared sensitivity of some bottom quark mass definitions is examined in some detail.Invited talk presented at RADCOR-2000, Carmel, CA, Sep. 2000; 15 pages, latex, 3 postscript figures; eliminated typo in Eq.(3)High Energy Physics - Phenomenologytext