We study gauge mediation of supersymmetry breaking in SU(5) supersymmetric grand unified theory with gauge fields as messengers. The generated soft supersymmetry breaking parameters lead to close to maximal mixing scenario for the Higgs mass and highly red
N=1vectormultipletVtransformsasanadjointofSU(5),thethreegenerationsofmatter eldsareinchiralmultiplets,3×(10+¯5),andtheHiggs eldsarein5+¯5.Besidesthese,wealsointroduceanadjointchiralmultipletΣ,andweassumethatbothitsscalarcomponent,whichwealsodenoteΣ,andtheauxiliarycomponent,FΣ,getvacuumexpectationvalues.TheVEVofFΣbreaksSUSYandtheSUSYbreakingiscommunicatedtogauginos,squarksandsleptonsthroughgaugeinteractions.ThemassivecomponentsofthegaugemultipletVandΣplaytheroleofmessengers.Thisistheminimal eldcontentweconsider.Inthiscase,thebetafunctioncoe cientoftheuni edgaugecouplingisbG=3andallsoftSUSYbreakingparametersattheGUTscalearecalculableintermsofbGandtheuni edgaugecoupling.
Itisalsopossibletoextendthemessengersectorandintroduce,forexample,apairof
5representationsofSU(5).Additionalmessengersusualmessenger eldsΦandΦcin5and¯
alsochangethebetafunctioncoe cient,bG=3andthespectrumisingeneralgivenintermsofthenumberofmessengers,Nmess,andbG.
Therefore,inthisscenariothemediationofsupersymmetrybreakingisacombinationoftwoe ects:
Gaugemessengercontribution:XandYgaugebosonsandgauginoscontributetothesoftsupersymmetrybreakingterms.TheybecomemassivebytheVEVofΣandgauginomassesgetsplitduetoFΣ.Therefore,themessengerscaleistheGUTscale.Theratio|FΣ
FΣ 4π
Inprincipleitispossibletointroduceanadditionalsingletsuper eld,whoseFcomponentisnon-zero,andwhichcouplestothevector-likemattermessengers.However,weconsideronlytheminimalversioninwhichΦandΦccoupletotheadjointΣbywhichgaugemessengersgottheirmasssplitting.3