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
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Figure4:Allowedregionofparameterspaceandthedegreeof netuningintheMSUSY cHuplaneforgaugemediation,Nmess=0andbG=3,withacontributionfromgravitymediationintheHiggssector.We xtanβ=25andcHd=50.0.Themeaningofexcludedregionsisthesame
1andτasinFig.2.Theblackdashedlineseparatesregionswheret 1areNLSP.
SofarwehavediscussedonlythecasewithNmess=0andbG=3.InFig.5we
alsopresentplotsofrenormalizationgrouprunningofsoftSUSYbreakingparametersforNmess=0andsmallervaluesofbGwhichcorrespondtoaddingmorecontenttotheminimalGUTscenario.Andforcompleteness,inthesame gurewealsoincludeNmess=1,bG=2casewhichcorrespondstotheminimalGUTcontentwithonepairofadditionalvector-likemessengersin5and¯5ofSU(5).InallcasesMSUSYandtanβare xedtothesamevaluewhichallowsustoseetrendsinthespectrumfromchangingthecontentofamodel.Forexactlythisreasonwedonotrequirethatalltheexperimentallimitsaresatis edinallmodels.Detailedinformationaboutthese vepointsisgiveninthelast vecolumnsinTable1.Thebasicfeaturesofallpresentedcasesareverysimilar.LoweringbGresultsinlightersquarkandsleptonspectrumbutslightlylargerstopmixing.Asaresult,theHiggsmassisdecreasingveryslowly.Addingadditionalpairofmessengerleadstolighterspectrumbecauseofthecancelationbetweencontributionsfromgaugemessengersandvector-likemessengersandthusinorderforthisscenariotobeviable,largerMSUSYisneeded.Wedonotdiscusspossibleadditionofgravitymediationforthesescenarios.
4.4LSPandNLSP
WhenthereisasizablecontributiontotheHiggssoftparametersfromgravitymediation,neutralinocanbeLSPorNLSPdependingonthegravitinomass.Inthisregion,neutralino
50606070708090 (GeV)SUSY