Radiative Enhancement of Stop Mixing

A supersymmetric extension of the Standard Model should rely on the mixing in the stop sector in order to accommodate the 125 GeV Higgs boson if the stops are around or below the multi-TeV, as would be required to avoid severe fine-tuning in the electroweak symmetry breaking and to achieve the gauge coupling unification. Using approximate analytic solutions to the renormalization group equations for the stop sector couplings, we examine how to enhance the stop mixing at low energy scales through radiative corrections. Sizable stop mixing can be obtained in the mediation scheme of supersymmetry breaking where the sum of the mass squareds for the scalar fields associated with the top quark Yukawa coupling is negative at the messenger scale. In addition, the gauginos can induce a considerable enhancement if they have non-universal masses at the unification scale, which is the case in the mixed mediation scheme where the relative strength of anomaly mediation is comparable to those of other flavor and CP conserving mediations, such as gauge and moduli mediation.