Making the small oblique parameters large

Abstract

We compute the oblique parameters, including the three new parameters $ V $, $ W $ and $ X $ introduced recently by the Montreal group, for the case of one scalar multiplet of arbitrary weak isospin $ J $ and weak hypercharge $ Y $. We show that, when the masses of the heaviest and lightest components of the multiplet remain constant, but $ J $ increases, the oblique parameter $ U $ and the three new oblique parameters increase like $ J^3 $, while $ T $ only increases like $ J $. For large multiplets with masses not much higher than $ m_Z $, the oblique parameters $ U $ and $ V $ may become much larger than $ T $ and $ S $.