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Magnetic Moment (G-2) and New Physics Magnetic moment (g − 2)µ and new physics Dominik Stöckinger Dresden Lepton Moments, July 2010 Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction exp SM A3σ deviation for aµ − aµ has been established! Currently: exp SM −11 aµ − aµ = (255 ± 63 ± 49) × 10 Expected with new Fermilab exp. (and th. progress): exp SM −11 aµ − aµ = (?? ± 16 ± 30) × 10 Which types of physics beyond the SM could explain this? What is the impact of aµ on physics beyond the SM? Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Outline 1 Introduction 2 Different types of new physics 3 aµ, parameter measurements and model discrimination SUSY could explain the deviation Littlest Higgs (T-parity) cannot explain the deviation Randall-Sundrum models could explain the deviation 4 Conclusions Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction Outline 1 Introduction 2 Different types of new physics 3 aµ, parameter measurements and model discrimination SUSY could explain the deviation Littlest Higgs (T-parity) cannot explain the deviation Randall-Sundrum models could explain the deviation 4 Conclusions Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction Muon magnetic moment Quantum field theory: Operator: aµ µ¯ σ qνµ mµ L µν R CP-, Flavour-conserving, chirality-flipping, loop-induced 2 Heavy particles contribute ∝ mµ Mheavy Sensitive to all SM interactions Sensitive to TeV-scale new physics in a unique way Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction Why new physics? Big questions EWSB, Higgs, mass generation? hierarchy MPl/MW ? Naturalness? Unification of the Coupling Constants in the SM and the minimal MSSM i i α 60 α 60 1/α 1/ 1/ 1 MSSM 50 50 40 40 α 1/ 2 30 30 20 20 10 10 α 1/ 3 0 0 0 5 10 15 0 5 10 15 10log Q 10log Q dark matter? Grand Unification? . point to the TeV scale. and to new physics Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction Why new physics? Big questions EWSB, Higgs, mass generation? hierarchy MPl/MW ? Naturalness? Unification of the Coupling Constants in the SM and the minimal MSSM i i α 60 α 60 1/α 1/ 1/ 1 MSSM 50 50 40 40 α 1/ 2 30 30 20 20 10 10 α 1/ 3 0 0 0 5 10 15 0 5 10 15 10log Q 10log Q dark matter? Grand Unification? Tevatron, LHC = era of TeV-scale physics Quest: discover new physics, solve big questions, understand EWSB Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction Why new physics? Big questions motivate radically new ideas — How can EWSB, light Higgs, MPl/MW be natural? Supersymmetry? Fermi-Bose symmetry ≈10 TeV strong dyn. ≈1 TeV Little Higgs? states WH , lH . ≈250 GeV Higgs=Pseudo SM, Higgs Goldstone Boson Randall-Sundrum? Warped extra dim. Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Introduction Why new physics? Big questions motivate radically new ideas — How can EWSB, light Higgs, MPl/MW be natural? Supersymmetry? Fermi-Bose symmetry ≈10 TeV strong dyn. ≈1 TeV Little Higgs? states WH , lH . ≈250 GeV Higgs=Pseudo SM, Higgs Goldstone Boson Randall-Sundrum? Warped extra dim. all these models predict aµ and are constrained by it Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Outline 1 Introduction 2 Different types of new physics 3 aµ, parameter measurements and model discrimination SUSY could explain the deviation Littlest Higgs (T-parity) cannot explain the deviation Randall-Sundrum models could explain the deviation 4 Conclusions Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Theory: g − 2 and chirality flips g − 2 = chirality-flipping interaction µR µL mµ = chirality-flipping interaction as well µR µL are the two related? Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Theory: g − 2 and chirality flips g − 2 = chirality-flipping interaction µR µL mµ = chirality-flipping interaction as well µR µL are the two related? New physics loop contributions to aµ, mµ related by chiral symmetry! [Czarnecki, Marciano ’01] 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) α C = O( ), Z ′, W ′, UED, Littlest Higgs (LHT). 4π (UED, LHT can mimic SUSY at the LHC) −11 δaµ ∼ 255 × 10 for M < 100GeV → very small! Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) α C = O( ), Z ′, W ′, UED, Littlest Higgs (LHT). 4π (UED, LHT can mimic SUSY at the LHC) −11 δaµ ∼ 255 × 10 for M < 100GeV → very small! such models already disfavoured by aµ, ruled out if deviation persists in new exp. Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) C = O(1), radiative muon mass generation technicolor, . [Czarnecki,Marciano ’01] −11 δaµ ∼ 255 × 10 for M > 1TeV → can be large! Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) C = O(1), radiative muon mass generation technicolor, . [Czarnecki,Marciano ’01] −11 δaµ ∼ 255 × 10 for M > 1TeV → can be large! lower mass bounds from aµ Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) α C = O(tan β ), supersymmetry 4π 1 C = O(nc 2 ), extra dimensions (Randall/Sundrum) 16π [Davoudiasl, Hewett, Rizzo ’00] large ED, unparticles,. [Park et al ’01] [Kim et al ’01] [Graesser,’00] [Cheung, Keung, Yuan ’07] −11 δaµ >, <, ∼ 255 × 10 possible → can fit well! Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics Classification of new physics 2 mµ δmµ(N.P.) generally: δaµ(N.P.)= O(C) , C = M mµ α Allows to classify new physics: C = O( 4π ), O(1), O(intermediate) α C = O(tan β ), supersymmetry 4π 1 C = O(nc 2 ), extra dimensions (Randall/Sundrum) 16π [Davoudiasl, Hewett, Rizzo ’00] large ED, unparticles,. [Park et al ’01] [Kim et al ’01] [Graesser,’00] [Cheung, Keung, Yuan ’07] −11 δaµ >, <, ∼ 255 × 10 possible → can fit well! strong constraints on model parameters and model building Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics g − 2 and new physics Different types of new physics can lead to very different contributions to aµ SUSY, RS, ADD, . : constrain parameters Z ′, UED, LHT, . : ruled out if deviation confirmed aµ can sharply distinguish between different types of new physics Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics g − 2 and new physics Different types of new physics can lead to very different contributions to aµ SUSY, RS, ADD, . : constrain parameters Z ′, UED, LHT, . : ruled out if deviation confirmed aµ can sharply distinguish between different types of new physics This will be even more the case with a new, improved measurement! Dominik Stöckinger Magnetic moment (g − 2)µ and new physics Different types of new physics g − 2 and new physics Different types of new physics can lead to very different contributions to aµ SUSY, RS, ADD, . : constrain parameters Z ′, UED, LHT, . : ruled out if deviation confirmed aµ can sharply distinguish between different types of new physics And even for models we haven’t yet thought of! Dominik Stöckinger Magnetic moment (g − 2)µ and new physics aµ, parameter measurements and model discrimination Outline 1 Introduction 2 Different types of new physics 3 aµ, parameter measurements and model discrimination SUSY could explain the deviation Littlest Higgs (T-parity) cannot explain the deviation Randall-Sundrum models could explain the deviation 4 Conclusions Dominik Stöckinger Magnetic moment (g − 2)µ and new physics aµ, parameter measurements and model discrimination SUSY could explain the deviation SUSY and the MSSM Big question: Why is there a Higgs scalar, why is it light? Answer: SUSY needs scalars, protects their masses, can even generate Higgs potential free parameters: p˜ masses and mixings, hH i tan β = 2 → structure of EWSB hH1i µ = H2 − H1 transition → SUSY parameter, much discussed Dominik Stöckinger Magnetic moment (g − 2)µ and new physics aµ, parameter measurements and model discrimination SUSY could explain the deviation g − 2 and SUSY g − 2 = chirality-flipping interaction aµ ν µ¯Lσµνq µR mµ How is this generated in SUSY? Dominik Stöckinger Magnetic moment (g − 2)µ and new physics aµ, parameter measurements and model discrimination SUSY could explain the deviation g − 2 and SUSY g − 2 = chirality-flipping interaction aµ ν µ¯Lσµνq µR mµ How is this generated in SUSY? chiral symmetry broken by λµ and mµ = λµhH1i hH2i two Higgs doublets: tan β = , µ = H2 − H1 transition hH1i ⇒ all terms ∝ λµ but two options: Dominik Stöckinger Magnetic moment (g − 2)µ and new physics aµ, parameter measurements and model discrimination SUSY could explain the deviation g − 2 and SUSY ∝ λµhH1i = mµ ∝ λµ µhH2i = mµ µ tan β potential enhancement ∝ λµ ∝ tan β = 1 .
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