Clean test of electroweak quantum effects independent of low-energy neutral-current processes

Electroweak quantum effects are studied in the ${\mathit{M}}_{\mathit{W}}$-${\mathit{M}}_{\mathit{Z}}$ relation by using recent data of ALEPH, DELPHI, L3, OPAL, and Mark II Collaborations on ${\mathit{M}}_{\mathit{Z}}$, and those of CDF and UA2 Collaborations on ${\mathit{M}}_{\mathit{W}}$. It is shown that these data demand the existence of a ${\mathit{G}}_{\mathit{F}}$ ${\mathit{m}}_{\mathit{t}}^2$-type correction in addition to the well-known logarithmic terms, which gives new phenomenological support to the electroweak theory independent of the neutral-current data.