Supersymmetryand other theories of Dark Matter CandidatesOverviewObligatory Standard Model SlideHierarchy ProblemHow does SUSY Help?Basics of SuSyThe MathematicsEliminating Quadratic DivergencesNaming SchemeA typical SuSy decay modeHow could we see it?Common Types of SuSyWhy is this a Dark Matter Candidate?What are the Candidates?What if we don’t see SUSY?Other theories that provide DMCSummaryReferences798G 3/1/07798G 3/1/07 11SupersymmetrySupersymmetryand other theories of and other theories of Dark Matter CandidatesDark Matter CandidatesEllie LocknerEllie Lockner798G Presentation798G Presentation3/1/073/1/07798G 3/1/07798G 3/1/07 22OverviewOverviewWhy bother with a new theory?Why bother with a new theory?Why is Why is SupersymmetrySupersymmetrya good a good solution?solution?Basics of Basics of SupersymmetrySupersymmetryWhy this leads to Dark Matter Why this leads to Dark Matter CandidatesCandidatesOther theoretical basis for Dark Other theoretical basis for Dark Matter CandidatesMatter Candidates798G 3/1/07798G 3/1/07 33Obligatory Standard Model SlideObligatory Standard Model Slide3 categories of particles:3 categories of particles:••QuarksQuarks••LeptonsLeptons••Bosons (force mediating)Bosons (force mediating)LagragianLagragianfor 3 of 4 for 3 of 4 fundamental forcesfundamental forcesBeen supported by Been supported by SIGNIFICANT experimental SIGNIFICANT experimental datadataRequires Scalar Boson Requires Scalar Boson (Higgs) as a mechanism to (Higgs) as a mechanism to explain why Z, W massiveexplain why Z, W massive798G 3/1/07798G 3/1/07 44Hierarchy ProblemHierarchy ProblemQuadratic Quadratic divergence in divergence in Higgs loopsHiggs loopsCan’t renormalize Can’t renormalize Higgs mass without Higgs mass without significant significant cancelationscancelationsElectroweak scale Electroweak scale vs. Planck scalevs. Planck scale798G 3/1/07798G 3/1/07 55How does SUSY Help?How does SUSY Help?Unification of ForcesUnification of Forces••Energy dependent Energy dependent coupling coupling parameters meet parameters meet with SUSYwith SUSYHiggs MassHiggs Mass••Divergences cancel Divergences cancel due to opposite due to opposite sign contributionssign contributionsAbundance of matter Abundance of matter over antimatter, size over antimatter, size and age of universe, and age of universe, proton decay, …proton decay, …798G 3/1/07798G 3/1/07 66Basics of Basics of SuSySuSyWhat is a symmetry?What is a symmetry?••LagrangianLagrangianremains unchanged under a remains unchanged under a transformation of the fieldstransformation of the fields••Ex: SM Ex: SM LagrangianLagrangiandoesn’t change if fields are doesn’t change if fields are “boosted” (transformed to moving frame using “boosted” (transformed to moving frame using Spec. Spec. RelRel.).)What is a SUPER symmetry?What is a SUPER symmetry?••Transformation of fields include fields of Transformation of fields include fields of opposite natureopposite nature••Terms cancel in Terms cancel in LagrangianLagrangianwhen all fields when all fields transformed, leaving it changed by only a transformed, leaving it changed by only a derivativederivative798G 3/1/07798G 3/1/07 77The MathematicsThe MathematicsWessWess--ZuminoZuminoModelModel798G 3/1/07798G 3/1/07 88Eliminating Quadratic DivergencesEliminating Quadratic Divergences798G 3/1/07798G 3/1/07 99Naming SchemeNaming SchemeFermions get Fermions get an “s” in an “s” in frontfrontBosons get Bosons get an “an “--inoino” at ” at the endthe endSymbols get Symbols get a “~” on top.a “~” on top.798G 3/1/07798G 3/1/07 1010A typical A typical SuSySuSydecay modedecay mode798G 3/1/07798G 3/1/07 1111How could we see it?How could we see it?The Lightest The Lightest SupersymmetricSupersymmetricParticle (LSP) Particle (LSP) neutral, so only neutral, so only interact via weak interact via weak forceforceVery hard to Very hard to detect, so seen as detect, so seen as Missing Transverse Missing Transverse Energy in decaysEnergy in decays798G 3/1/07798G 3/1/07 1212Common Types of Common Types of SuSySuSyMSSMMSSM••Minimal Minimal SupersymmetricSupersymmetricModelModel••Adds fewest number of new particlesAdds fewest number of new particles••Adds new conserved quantum number: Adds new conserved quantum number: R = (R = (--1)1)3(B3(B--L)+2SL)+2SmSUGRAmSUGRA••Minimal Minimal SupergravitySupergravity••Decreases # of parameters from >100 to 5 by Decreases # of parameters from >100 to 5 by grouping some together and requiring they be grouping some together and requiring they be equalequal798G 3/1/07798G 3/1/07 1313Why is this a Dark Matter Why is this a Dark Matter Candidate?Candidate?Dark matter must interact only via the Dark matter must interact only via the weak forceweak force••If electrically or color charged would see it in If electrically or color charged would see it in Nuclear effects such as anomalously heavy Nuclear effects such as anomalously heavy ions, “Very hard to hide Baryons.”ions, “Very hard to hide Baryons.”If R quantum # conserved the Lightest If R quantum # conserved the Lightest SupersymmetricSupersymmetricParticle (LSP) would be Particle (LSP) would be stablestableLSP must be relatively massive since LSP must be relatively massive since hasn’t been detected yethasn’t been detected yet798G 3/1/07798G 3/1/07 1414What are the Candidates?What are the Candidates?GravitinoGravitino••Very difficult to Very difficult to confirm or excludeconfirm or excludeSneutrinoSneutrino••In MSSM has been In MSSM has been excluded by direct excluded by direct and indirect and indirect searchessearchesNeutralinoNeutralinoCould be Could be photinophotino, , binobino, or , or HiggsinosHiggsinos798G 3/1/07798G 3/1/07 1515What if we don’t see SUSY?What if we don’t see SUSY?There must be modifications to SMThere must be modifications to SMSUSY provides an EXTENSION of SM, SUSY provides an EXTENSION of SM, leaving most of it intactleaving most of it intactTime to scrap SM and start over?Time to scrap SM and start over?New theories that avoid quadratic New theories that avoid quadratic divergences (renormalization?), divergences (renormalization?), explain hierarchy problem,