Naturalness And Supersymmetry (standard Model, Electroweak Symmetry, Gauge Mediation)

In the Standard Model of elementary particle physics, electroweak symmetry breaking is achieved by a Higgs scalar doublet with a negative (mass)$\sp2$. The Standard Model has the well known gauge hierarchy problem: quadratically divergent quantum corrections drive the Higgs mass and thus the weak scale to the scale of new physics. Thus, if the scale of new physics is say the Planck scale, then correct electroweak symmetry breaking requires a fine tuning between the bare Higgs mass and the quantum corrections. Supersymmetry, a symmetry between fermions and bosons, solves the gauge hierarchy problem of the Standard Model: the quadratically divergent corrections to the Higgs mass cancel between fermions and bosons. The remaining corrections to the Higgs mass are proportional to the supersymmetry breaking masses for the supersymmetric partners (the sparticles) of the Standard Model particles. The large top quark Yukawa coupling results in a negative Higgs (mass)$\sp2$..