Towards a dynamical determination of parameters in the Minimal Supersymmetric Standard Model

In the M inim alSupersym m etric Standard M odel(M SSM ),the scale M SU SY ofsoft supersym m etry breaking is usually assum ed to be ofthe order ofthe electroweak scale.W e reconsiderhere the possibility oftreating M SU SY asa dynam icalvariable. Itsexpectation value should be determ ined by m inim izing the vacuum energy,after including M SSM quantum corrections. W e pointout the crucialrole ofthe cosm ologicalterm fora dynam icalgeneration ofthedesired hierarchies m Z ;M SU SY (cid:28) M P . Inspired by four-dim ensionalsuperstring m odels,we also considerthe Yukawa couplings as dynam icalvariables. W e (cid:12)nd that the top Yukawa coupling is attracted close to its e(cid:11)ective infrared (cid:12)xed point,corresponding to a top-quark m ass in the experim entally allowed range. A s an illustrative exam ple,we presentthe results of explicitcalculations fora specialcase ofthe M SSM .