Mediation of Supersymmetry Breaking in Gauge Messenger Model(14)

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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Figure2:Allowedregionofparameterspaceandthedegreeof netuningintheMSUSY tanβplaneforpuregaugemediation,Nmess=0andbG=3.TheshadedregionsareexcludedbydirectsearchesforSUSYandHiggsparticles.WeusethelimitsonthemassofthelightestHiggsboson,mh0>114.4GeV,thelighteststop,mt >95.7GeV,thelighteststau,mτ >81.9GeV,andthelightestchargino,mχ±>117GeV.Theregiondenotedas“tachyon”isexcludedduetotachyonicspectrum.TheblackdashedlineseparatesregionswheresneutrinoorstauisNLSP.

Sincethereareonlytwoparametersinthismodel,itiseasytoexplorethewhole

parameterspace.InFig.2weshowallowedparameterspaceinMSUSY–tanβplane,togetherwithregionsexcludedbydirectsearchesforSUSYandHiggsparticles.Moderatetolargetanβisallowedand,asusual,assmallMSUSYwhichstillsatis esthelimitontheHiggsmassispreferredbynaturalness.InmostregionoftheparameterspacesneutrinoisNLSPforsmalltanbeta(gravitinoistheLSP)andstauisNSLPforlargetanbetaduetolargemixingoftheleftandright-handedstau.Arepresentativepointfromthisregionisgiveninthe rst(stauNLSP)andthethirdcolumn(sneutrinoNLSP)ofTable1.Aswewilldiscusslater,smallcontributionsfromgravitymediationcaneasilypushsneutrinoorstauabovethelightestneutralinoleadingtoalargeregionwhereneutralinois(N)LSP.

4.2GaugemediationwithgravitycontributionintheHiggssector

Addingacontributionfromgravitymediationopensapossibilityofgeneratingtheµhttp://www.77cn.com.cnparableinsizesoftmassessquaredforHuandHdarealsogenerated.WeparameterizeadditionalcontributiontotheHiggssoftmasses

22squaredby:cHuMSUSYandcHdMSUSY.Anexampleoftherenormalizationgrouprunning

ofsoftSUSYbreakingparametersinthiscaseisgiveninFig.3anddetailedinformationaboutthisscenariocanbefoundinthesecondcolumnofTable1.Addinggravitycontribu-tiontosoftHiggsmassessquareddoesnotsigni cantlya ectrunningofothersoftSUSY

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