Radiatively induced light right-handed stop

A right-handed stop not much heavier or even lighter than the Z boson has today desirable phenomenological consequences. We study how it can result within the usual radiative scenario of electroweak symmetry breaking. A restriction on the gaugino mass parameters, M_2 < 0.3 m_10, arises if soft terms satisfy relations suggested by unification theories. Moreover, requiring to get a light stop without unnatural fine-tunings below the per-cent level, we obtain another more interesting upper bound on the chargino mass, M_chargino < M_Z, and we derive interesting conclusions about the masses of the gluino, M_3 \sim (150-300) GeV, of the heavy stop, M_stop \sim (250-500) GeV, and of the left/right mixing angle in the stop sector, |\theta_stop| < 0.3.