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Low Energy Electroweak Precision Tests

Low Energy Electroweak Precision Tests. Perspective Motivations Precision program WNC experiments Universality EDMs, g-2 FCNC. Motivations. WNC, Z, W established SU(2) X U(1) SM Z pole most precise (0.1%) and excluded many BSM scenarios

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Low Energy Electroweak Precision Tests

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  1. Low Energy Electroweak Precision Tests • Perspective • Motivations • Precision program • WNC experiments • Universality • EDMs, g-2 • FCNC P. Langacker ICHEP2004 (8/16/04)

  2. P. Langacker ICHEP2004 (8/16/04)

  3. Motivations • WNC, Z, W established SU(2) X U(1) SM • Z pole most precise (0.1%) and excluded many BSM scenarios • However, Z pole is blind or less sensitive to many types of new physics (Z’, SUSY loops, RPV, new operators, exotics, leptoquarks, LED) • Running sin2qW (new physics) • Precision low energy WNC (few percent) still important • FCNC, g-2, EDMs complementary to WNC, Z pole and collider P. Langacker ICHEP2004 (8/16/04)

  4. A Heavy Z’? • Strings, GUTs, LED, DSB, Little Higgs (best motivated after SUSY) • Solution to m problem • Highly nonstandard Higgs (doublet-singlet mixing) and neutralino sectors • Chiral exotics • Electroweak baryogenesis • Cold dark matter • Family nonuniversality: tree level contribution to rare B decays P. Langacker ICHEP2004 (8/16/04)

  5. Weak Neutral Current below the Z-pole • Z-pole insensitive to effects not directly involving Z • Loop effects from new physics: (/)(M/Mnew)2 (Shufang Su) • muon g-2: M=m , new  2x10-9, exp < 10-9 • -decay, -decay: M=mW , new  10-3, exp  10-3 • parity-violating electron scattering: M=mW , new  10-3 • Also, suppression QWe,p 1-4 sin2W  0.1 P. Langacker ICHEP2004 (8/16/04)

  6. (Shufang Su) P. Langacker ICHEP2004 (8/16/04)

  7. RPV 95% CL MSSM loop Kurylov, Ramsey-Musolf, Su (2003) P. Langacker ICHEP2004 (8/16/04)

  8. (Run I) SLAC E158 Moller Scattering e-e- polarization asymmetry, P = 85% I + II prelim: Ds2=0.0021 Compositeness scale: 10 TeV; Z’ ~0.8 TeV Run III (summer 04): 0.0015 (Kolomensky talk on E158 website) P. Langacker ICHEP2004 (8/16/04)

  9. P. Langacker ICHEP2004 (8/16/04)

  10. P. Langacker ICHEP2004 (8/16/04)

  11. P. Langacker ICHEP2004 (8/16/04)

  12. Qweak (Jlab) Ds2~0.0007 Complementary to Moller Form factors can be measured P. Langacker ICHEP2004 (8/16/04)

  13. Atomic Parity Violation • Very sensitive to Z’, leptoquarks, RPV • Washington: thallium (optical rotation) 1%, but theory 2.7% • Boulder: cesium (Stark) • QW = -72.69(48) (SM: -73.19(3)) • “turbulent 2 yr” (Breit, vacuum pol., aZ vertex, nuclear skin) • Anapole: discrepancy with nuclear physics expectations • Future • Paris cesium- may become competitive • Berkeley: Yb isotopes (wave functions cancel, but nuclear radius; reduced sensitivity to new physics) • Washington: Ba+ ions (0.1% may be possible) • KVI: Ra+ considered P. Langacker ICHEP2004 (8/16/04)

  14. NuTeV NC/CC; n and n-bar 3s discrepancy in RnN P. Langacker ICHEP2004 (8/16/04)

  15. Beyond standard model strained • Not SUSY loops or RPV • Hard to fit leptoquark • Designer Z’ possible • Mixing of n- nheavy + more miracles • Radiation from final lepton in cc (needs checking) • NLO QCD: suppressed by sin4qW but may be important • New analysis very important • Nuclear effects unlikely • 30% s-sbar asymmetry possible (controversial) • 5% isospin breaking possible, but naively expect 0.5% • NOMAD, Qweak, other JLAB P. Langacker ICHEP2004 (8/16/04)

  16. NOMAD • nm -> nt, ne oscillations • Deep inelastic scattering (CC and NC) • Expect 1% sin2qW P. Langacker ICHEP2004 (8/16/04)

  17. Outlook • NOMAD • QWEAK • Possible APV • Possible reactor ne-bar, in conjunction with oscillation experiment (D s2W~0.001) • Near detectors for long baseline? • Neutrino factory? P. Langacker ICHEP2004 (8/16/04)

  18. CKM Universality • |Vud|2 + |Vus|2 + |Vub|2~ |Vud|2 + |Vus|2  1 – D • PDG 2002: D = 0.0042 ± 0.0019 • New physics? Constrains n-nheavy explanations of NuTeV • Problem in Vud? • Superallowed: |Vud|=0.9740(5), many checks • Neutron: 0.9745 (16) (common structure-independent rad corr) • Pion beta decay: 0.9716(39) (new) • Problem in Vus? P. Langacker ICHEP2004 (8/16/04)

  19. PDG value mainly from old Ke3. Radiative corrections? • New BNL865 K+, KTEV KL, KLOE KS consistent with D=0. • Not CERN NA48. • Also hyperon decay data (theory errors) (C. Quigg) P. Langacker ICHEP2004 (8/16/04)

  20. P. Langacker ICHEP2004 (8/16/04)

  21. The BNL g-2 experiment

  22. P. Langacker ICHEP2004 (8/16/04)

  23. P. Langacker ICHEP2004 (8/16/04)

  24. Discrepancy between e+e- and t decay • New e+e- data • Work on isospin violation • Hadronic light by light • If real discrepancy then SUSY with large tan b and low masses is possibility: tan b/(MSUSY/100 GeV)2~2 • Proposal to improve experimental error by 2 • Can theory error keep up? P. Langacker ICHEP2004 (8/16/04)

  25. S d P T Electric Dipole Moments • New probe of T (CP) violation • New phases needed for baryogenesis • EDMs small in SM, large in most BSM, e.g. SUSY • MSSM: 62 new real parameters and 43 new phases • Universal soft breaking => two new phases • fA = arg(A* m1/2), fB = arg(B* m m1/2) • (300 GeV/m)2 sin fA,B < 10-2 P. Langacker ICHEP2004 (8/16/04)

  26. e e Electron EDM in various SM extensions not renormalizable  loop diagrams Experimental limit: |de| < 1.610-27 ecm B. Regan, E. Commins, C. Schmidt, D. DeMille, PRL 88, 071805 (2002) Models assume new physics at ~100 GeV & CP-violating phases ~1 (D. DeMille)

  27. P. Langacker ICHEP2004 (8/16/04)

  28. Current status of ALL EDM searches (D. DeMille) Best limits on “natural” parameters from 3 complementary experiments: P. Langacker ICHEP2004 (8/16/04)

  29. A new generation of electron EDM searches (D. DeMille) P. Langacker ICHEP2004 (8/16/04)

  30. Flavor Violation • Lepton flavor almost conserved in SM (up to mn) • Violated in SUSY, multi-Higgs, heavy n, leptoquark, non-universal Z’, compositeness • MECO (BNL): (mN->eN)/(mN->nN) to 2 x 10-17 • Sensitive to many BSM • SINDRUM: 6.1 x 10-16 • Future: PRIME at PRISM: 10-18 • also, m->eg at PSI: 10-13 (2 orders) • Rare B, K decays? E.g., B-> fKs (Belle, not BaBar), pK; K -> p n n-bar • (Tree level Z’ vs SM and SUSY loops.) P. Langacker ICHEP2004 (8/16/04)

  31. P. Langacker ICHEP2004 (8/16/04)

  32. TWIST Left/Right Mixing constraints – Anticipated TWIST Sensitivity • Measure m decay electron spectrum/angular distribution precisely • Sensitive to new couplings, including RHC (eg, WR) • 2 x 10-4 in 05/06 Mixing angle  P. Langacker ICHEP2004 (8/16/04)

  33. Summary • Intellectual prospects in high energy physics have never been higher • Theoretical opportunities for standard model of everything, but must make connections • Experimental exploration of TeV scale and beyond • Collider searches: LHC is likely to be a rich but complicated discovery machine • Precision, rare/suppressed, neutrino experiments will give complementary constraints • 10 yr ago: almost every extension of SM yields neutrino masses/mixings at some level • Now: almost every extension of SM yields EDMs, FCNC at some level, and may be other surprises P. Langacker ICHEP2004 (8/16/04)

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