Electric dipole moments: theory and experiment

Transcription

1 Electric dipole moments: theory and experiment EA Hinds Blois June 2002

2 Two motivations to measure EDMs EDM violates T symmetry Deeply connected to CP violation and the matter-antimatter asymmetry of the universe EDM is effectively zero in standard model but big enough to measure in non-standard models direct test of physics beyond the standard model

3 A bit of history Experimental Limit on d (e.cm) neutron: electron: Multi Higgs Left-Right Electromagnetic SUSY φ 1 φ α/π Standard Model

4 CP from particles to atoms (main connections) field theory CP model electron/quark level nucleon level nuclear level atom/molecule level Higgs SUSY Left/Right d e d q neutron thallium d c q Strong CP qgg% NNNN Schiff moment mercury

5 The Mercury EDM experiment University of Washington, Seattle M.V. Romalis, W.C. Griffith, J.P. Jacobs, E.N. Fortson Nuclear spin polarised 199 Hg vapor in a double cell B hw = mb ± + de - de E w ± measured optically

6 Difference of precession frequencies gives 199 Hg EDM 199 Hg EDM (10-27 e.cm) E = 9 kv/cm B = 15 µt stable to 0.4 pt T coherence ~ 100 s Hg edm result: Phys. Rev. Lett. 86, 2505 (2001) d Hg < e cm GSI992

7 The Neutron EDM Rutherford-Appleton Laboratory CA Baker, K Green, P Iaydjiev, S Ivanov Sussex University S Al-Ayoubi, PG Harris, JM Pendlebury, JD Richardson, D Shiers, K F Smith, M van der Grinten ILL P Geltenbort Ultracold neutrons in a bottle precess at frequency (m n B d n E)/h Reverse E to measure d n

8 E = 4.5 kv/cm B = 1 µt T coherence ~ 130 s Hg co-magnetometer (B is measured to 1 pt rms) Neutron edm result: Phys. Rev. Lett. 82, 904 (1999) d n < e cm GSI992

9 Neutron: longer range plans New moderators using liquid helium or solid deuterium Helium (ILL, LANL) Inside the helium Higher neutron density Higher E field Deuterium (PSI, TU-Munich) Outside the deuterium Higher neutron density Bigger volume (fast moderation) Aiming at e.cm over next decade

10 Implications of n and Hg for the theta parameter CP strong interaction induces neutron EDM Baluni Crewther Pospelov p - g d n θ n p n ॐ θ < q g s 2 ~ 32p 2GG Something N (Peccei-Quinn?) makes θ very small! N / induces mercury Schiff moment Henley & Haxton Pospelov p d Hg θ ॐ θ <

11 q squark gaugino q quark electric dipole moments g Implications of Hg and n for SUSY q squark gaugino g q quark color dipole moments 1 2 d q q (F µν σ µν iγ 5 ) q d q q (g s G µν σ µν iγ 5 ) q 1 c 2 c naturally ~ α/π d q, d q ~ (loop factor) scale of SUSY breaking naturally ~200 GeV m q 2 L CP phase from soft breaking naturally O(1) sin j CP c d u,d, d u,d ~ cm naturally n and Hg experiments give d u < d d < c d u < c d d < ϕ CP < ?? ~ 300 times less! Λ > 5 TeV??

12 CP from particles to atoms (main connections) field theory CP model electron/quark level nucleon level nuclear level atom/molecule level Higgs SUSY Left/Right d e d q neutron thallium d c q Strong CP qgg% NNNN Schiff moment mercury

13 And now for the electron..

14 Berkeley The Thallium EDM experiment B.C. Regan, E.D. Commins, C.J. Schmidt and D. DeMille polarise analyse 1st huge problem: motional interaction µ v E The solution: add 2 more Tl beams going down B E hw = mb ± ± de 2 nd huge problem: stray static magnetic fields polarise analyse 42 Tl atomic beams The solution: Add 4 Na beams for magnetometry

15 A beautiful feature of the method amplification (Sandars) E ηd e s Interaction energy -d e ηe s atom containing electron -585 for Tl electric field

16 Final Tl result: PRL 88, (2002) E = 123 kv/cm B = 38 µt T coherence = 2.4 ms Na co-magnetometer 585 Effective field = 72 MV/cm d Tl < e.cm 585 electron edm result: d e < e.cm

17 Theoretical consequences of electron EDM No direct contamination from θ problem - a pure new physics search selectron g e e SUSY electron edm d e ~ (loop) m e 2 L ~ cm sin j CP Once again, natural SUSY is too big by 300 ϕ CP < ?? Λ > 5 TeV??

18 The future for electron EDM experiments polar molecules potentially 1000 more sensitive The Sussex experiment uses ytterbium fluoride molecules JJ Hudson, BE Sauer, MR Tarbutt and EA Hinds, arxiv hep-ex (2002)

19 First advantage of YbF: 13 GV/cm Effective field ηe (GV/cm) Applied field E (kv/cm) Huge effective field ηe Parpia Quiney Kozlov Titov (in Tl experiment ηε was 72 MV/cm)

20 2nd advantage of YbF: No coupling s E v to motional magnetic field electron spin s is coupled to internuclear axis and internuclear axis is coupled to E Yb + s F - E \< s E > = 0 no motional systematic error

21 The Sussex molecular beam detect PMT analyse 1.5 m beam B and E polarise state select oven

22 Part of the optical setup

23 Measuring the edm cos 2 w - T cos 2 w + T Detector count rate - 4d e het/h df = 4d e het/h -B 0 B 0 Applied magnetic field

24 Projections for the future 2002 result cold YbF beam trapped molecules background 150kHz 640kHz 40kHz fringe height 1.5 khz 160 khz 10 khz coherence time 1.5 ms 1 ms 1 s d e in 1 day e cm e cm e cm long time = narrow fringes

25 Current status of EDMs neutron: electron: YbF expt d e.cm Multi Higgs Left-Right Electromagnetic SUSY φ 1 φ α/π d(muon) d(proton) d(neutron) cold molecules 26 d(electron)

26 Conclusion EDM measurements (especially cold moleules) have great potential to elucidate CP violation particle physics beyond the standard model matter/antimatter asymmetry of the universe some of the most fundamental issues in physics

27