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Another Route to CP Violation Beyond the SM – Particle Dipole Moments

Another Route to CP Violation Beyond the SM – Particle Dipole Moments. Dave Wark Imperial/RAL. WIN05 Delphi June 10, 2005. WIN05. June 10 ’05. nEDM…. ⇀. Would lead to a non-zero value for d n , either parallel or anti-parallel to s. ⇀. …and CP. Particle Electric Dipole Moment. _.

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Another Route to CP Violation Beyond the SM – Particle Dipole Moments

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  1. Another Route to CP Violation Beyond the SM –Particle Dipole Moments Dave Wark Imperial/RAL WIN05 Delphi June 10, 2005

  2. WIN05 June 10 ’05 nEDM… ⇀ Would lead to a non-zero value for dn, either parallel or anti-parallel to s ⇀ …and CP Particle Electric Dipole Moment _ ⇀ s + ⇀ dn would be: P odd T odd CP odd! Dave Wark Imperial College/RAL

  3. WIN05 June 10 ’05 nEDM… neutron …and CP electron Dave Wark Imperial College/RAL 10-20 10-22 10-24 10-26 Range of d (e cm) in various models 10-28 10-30 10-32 10-34 Standard Model 10-36 10-38

  4. WIN05 Strong CPV  dn ~ 10-16 ecm June 10 ’05 nEDM… …and CP Electro- 10-20 magnetic 10-22 10-24 Multi Range of d (e cm) in various models SUSY Higgs f ~ 1 f ~ a/p Left-Right 10-30 neutron 10-32 10-34 Standard Model 10-36 electron Dave Wark 10-38 Imperial College/RAL

  5. WIN05 Strong CPV  dn ~ 10-16 ecm June 10 ’05 Electro- 10-20 10-20 magnetic electron: 10-22 neutron: nEDM… 10-24 Experimental Limit on d (e cm) Multi SUSY Higgs f ~ 1 f ~ a/p Left-Right 10-30 10-30 1960 1970 1980 1990 2000 10-32 10-34 …and CP Standard Model 10-36 Dave Wark 10-38 Imperial College/RAL Range of d (e cm) in various models neutron Relative value of neutron and electron EDM is model- dependent, must pursue both electron

  6. WIN05 Strong CPV  dn ~ 10-16 ecm June 10 ’05 Electro- 10-20 10-20 magnetic electron: 10-22 neutron: nEDM… 10-24 Experimental Limit on d (e cm) Multi SUSY Higgs f ~ 1 f ~ a/p Left-Right 10-30 10-30 1960 1970 1980 1990 2000 10-32 Cited >200 times already 10-34 …and CP Standard Model 10-36 10-38 Range of d (e cm) in various models neutron electron Dave Wark Imperial College/RAL

  7. WIN05 June 10 ’05 nEDM… …and CP +e Dx -e If neutron were the size of the earth... ... current EDM limit would correspond to charge separation of Dx  10 . Dave Wark Imperial College/RAL

  8. WIN05 June 10 ’05 nEDM… B E mB dn ?? …and CP Basic Idea of the Measurement Dave Wark Imperial College/RAL

  9. WIN05 June 10 ’05 nEDM… …and CP Basic Idea of the Measurement B E mB dn ?? Look for a shift in the Larmor frequency of 2·E·dn as E is flipped relative to B Dave Wark Imperial College/RAL

  10. WIN05 June 10 ’05 nEDM… “Spin up” neutron... 1. …and CP Apply /2 spin flip pulse... 2. Free precession... 3. Second /2 spin flip pulse. 4. The Ramsey Separated Oscillator Method Dave Wark Imperial College/RAL

  11. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL

  12. WIN05 B June 10 ’05 nEDM… …and CP n s n s n >> interatomic spacing; neutrons see Fermi potential VF Critical velocity for reflection: ½mvc2 = VF Ultracold neutrons (UCN): v 6 m/s: total internal reflection possible. vc depends on orientation of neutron spin, so can polarise by transmission. Dave Wark Imperial College/RAL

  13. WIN05 June 10 ’05 nEDM… …and CP Prepare neutrons in polarisation state 1, execute Ramsey cycle and measure the number left in states 1 and 2, repeat with B and E fields parallel () and anti-parallel (), then: With the resulting “statistical” sensitivity: Must add any systematics to this to determine the sensitivity of the experiment. Dave Wark Imperial College/RAL

  14. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL The Institute Laue-Langevin

  15. WIN05 Four-layer mu-metal shield June 10 ’05 High voltage lead nEDM… Quartz insulating cylinder Coil for 10 mG magnetic field Upper electrode …and CP Main storage cell Dave Wark Imperial College/RAL Hg u.v. lamp PMT to detect Hg u.v. light Vacuum wall Mercury prepolarising cell RF coil to flip spins Hg u.v. lamp Magnet S N UCN guide changeover UCN polarising foil Ultracold neutrons (UCN) UCN detector Current Room- Temperature nEDM Experiment

  16. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL

  17. 1999 Results (PG Harris et al, PRL 82, 904 (1999)) WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL dn = (1.9  5.4)1026 e cm dn  6.3 1026 e cm (90% c.l.)

  18. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL Recall: Published Data Current Room-Temp Cryogenic Experiment α 0.7 0.5 E 4.5 kV/cm 12 kV/cm T 130 s 130 s N 13000 14000

  19. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL How will we do better? • Need a new source of UCN…. • To use this we need…. 1.03 meV

  20. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL Next Generation Experiment

  21. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL Ramsey Cell and SF Vessel

  22. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL Recall: Published Data Current Room-Temp Cryogenic Experiment α 0.7 0.9 0.5 E 40 kV/cm 4.5 kV/cm 12 kV/cm T 130 s 130 s 300 s N 13000 14000 700000

  23. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL

  24. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL 199Hg Electric Dipole Momenthep-ex/0012001 • Optically pumped 199Hg atoms precess in B, E fields, modulating absorption signal • Dual cells remove effect of drifts in B • Result: d(199Hg) < 2.1 x 10-28 e cm • Provides good limit on CPv effects in nuclear forces, inc. qQCD • If from valence neutron, corresponds to dn<2x10-25 ecm, because of electrostatic shielding.

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  31. WIN05 June 10 ’05 nEDM… …and CP Dave Wark Imperial College/RAL Conclusions • Particle EDMs are sensitive probes of CP violation both within (qs < 2-6 x 10-10) and in models beyond the SM (The natural scale for the nEDM is SUSY is 10-23, already stressed). • Experiments are in progress to improve sensitivities by factors 100-1000. • There are other competing experiments for both neutrons (PSI, US) and electrons that I have no time to discuss. • There are also plans to push limits on the muon EDM at future facilities (JPARC). • The two CP violation communities seem completely separate, which is a pity….

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