Stop-Stop-Higgs Production at future Linear Collider(2)

In the Minimal Supersymmetric Standard Model, the cross section for the associated production of the lightest neutral Higgs boson with the lightest top squark pairs can be rather substantial at high energies. We summarize the properties of this production

notconsiderotherHiggsproductionprocesseswithe.g.theheavyHorAbosonsproducedinassociationwithtopsquarks.Forlargemasses,theseprocesseswillbesuppressedbyphase–spacewellbeforethedecouplingregimeisreached.2

Associatedproductionate+e colliders

Atfuturelineare+e colliders,the nalstate t

1t 1hmaybegeneratedinthreeways:(i)two–bodyproductionofamixedpairoftopsquarksandthedecayoftheheavieststoptothelighteste+e annihilatione+e oneandaHiggsboson,(ii)thecontinuumproductionin

1γγ→ t

1t 1h.→t

t 1hand(iii)thecontinuumproductioninγγcollisions2.1Two–bodyproductionanddecay

Thetotalcrosssection11fortheprocess(i)should,inprinciple,belargeforthe nalstatetobecopiouslyproduced.However,σ(e+e 1 enough

t2)involvestheZ t1t 2coupling,proportionaltosin2θt,whilethe|ght →t

theparameterspaceisproportionaltocos2θ1t

2t,suchthatthe|couplingcrosssectioninmosttimesofbranchingratiowillbeverysmallinthenomixing[|θt [θt2smaller|～π/4]thancases.the t

[In2decayaddition,widthstheintodecaycharginowidtht

11and→～0]neutralinos].ht 1andisinmaximalgeneralmixing

muchNevertheless,thereareregionsoftheMSSMparameterspacewherethecombinationsin2θtcos2θtcanbelarge;thisoccurstypicallyforanottoosmallmt ×moderateA L–mt

Rsplittingandtvalues.5Inthiscase,whichisoftenrealizedinthemSUGRAscenario,thismechanismisvisiblefortheexpectedhighluminosities12

Ldt～500fb 1ThisisillustratedinFig.1,wherethecrosssectione+ branching√ratioBR( e 1 .

t2timesthet

2→t 1h)isshownasafunctionofthet →t

1massatac.m.energyof