Electric dipole moments : a search for new physics E.A. Hinds Manchester, 12 Feb 2004 Imperial College London

Fundamental inversions C particle antiparticle Pposition inverted T time reversed (Q -Q) (r -r) (t -t)

Symmetries Weak interactions are not symmetric under P or C normal matter - n, ,  - readily breaks C and P symmetry. The combination CP is different normal matter respects CP symmetry to a very high degree. Time reversal T is equivalent to CP (CPT theorem) normal matter respects T symmetry to a very high degree.

Electric dipole moment (EDM) breaks P and T symmetry P - + elementary particle + - spin edm (P no big deal) + - T + - (CP big deal)

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

Experimental Limit on d (e.cm) neutron: electron: A bit of history

thallium atom/molecule level CP from particles to atoms (main connections) nuclear level NNNN Schiff moment mercury Higgs SUSY Left/Right Strong CP field theory CP model  GG neutron nucleon level electron/quark level dede dqdcqdqdcq ~

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 h  =  B + dE E - dE ± B  ± measured optically

199 Hg EDM ( e.cm) GSI992 Hg edm result : Phys. Rev. Lett. 86, 2505 (2001) |d Hg | < 2.1  e cm E = 9 kV/cm B = 1.5  T stable to 0.4 pT T coherence ~ 100 s Difference of precession frequencies gives 199 Hg EDM

The Neutron EDM Rutherford-Appleton Laboratory D Wark, P Iaydjiev, S Ivanov, S Balashov, M. Tucker Sussex University PG Harris, JM Pendlebury, D Shiers, M van der Grinten, K Zuber, K Green, m Hardiman, P Smith, J Grozier, J Karamath ILL P Geltenbort Ultracold neutrons in a bottle precess at frequency (  n B  d n E)/  Reverse E to measure d n OXFORD H. Kraus N Jelley H Yoshiki KURE

GSI992 Neutron edm result : Phys. Rev. Lett. 82, 904 (1999) |d n |< 6.3  e cm E = 4.5 kV/cm B = 1  T T coherence ~ 130 s Hg co-magnetometer (B is measured to 1 pT rms)

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

Implications of n and Hg for the theta parameter  gs2gs2 32   GG ~ CP strong interaction d n    6  nn  p   × induces neutron EDM Baluni Crewther Pospelov Henley & Haxton Pospelov induces mercury Schiff moment N/N/  × N d Hg    2  Something (Peccei-Quinn?) makes  very small! 

Implications of Hg and n for SUSY quark electric dipole moments d q q (F    i  5 ) q 2 1 qq  gaugino squark quark color dipole moments qq g gaugino squark d q q (g s G    i  5 ) q 2 1 c 2  mqmq d q, d q ~ (loop factor)  sin  CP c CP phase from soft breaking naturally O(1) scale of SUSY breaking naturally ~200 GeV naturally ~  d u,d, d u,d ~ 3  10  24 cm naturally c n and Hg experiments give d u < 2  10  25 d d < 5  10  26 d u < 3  10  26 d d < 3  10  26 c c ~ 100 times less!  CP < ??  > 2 TeV ??

thallium atom/molecule level CP from particles to atoms (main connections) nuclear level NNNN Schiff moment mercury Higgs SUSY Left/Right Strong CP field theory CP model  GG  neutron nucleon level electron/quark level dede dqdcqdqdcq

And now for the electron………..

The Thallium EDM experiment Berkeley B.C. Regan, E.D. Commins, C.J. Schmidt and D. DeMille 2 Tl atomic beams   =  B polarise analyse ± dE E ± B The solution: add 2 more Tl beams going down 4 analyse polarise The solution: Add 4 Na beams for magnetometry 1st huge problem: motional interaction   v  E 2 nd huge problem: stray static magnetic fields

A beautiful feature of the method E electric field Interaction energy -d e  E  de de  atom containing electron amplification -585 for Tl (Sandars)

Effective field = 72 MV/cm  585 ÷ 585 electron edm result : |d e |< 1.6  e.cm E = 123 kV/cm B = 38  T T coherence = 2.4 ms Na co-magnetometer Final Tl result: PRL 88, (2002) |d Tl |< 9.4  e.cm

Theoretical consequences of electron EDM SUSY electron edm ee  selectron 2  meme d e ~ (loop)  sin  CP No direct contamination from  problem - a pure new physics search ~ 5  10  25 cm This time natural SUSY is too big by 300  CP < 3  ??  > 4 TeV ??

potentially 1000  more sensitive The Imperial experiment uses ytterbium fluoride molecules E.A. Hinds, B.E. Sauer, J.J. Hudson, P Condylis, M.R. Tarbutt, R. Darnley The future for electron EDM experiments polar molecules

(in Tl experiment  was 72 MV/cm) 13 GV/cm First advantage of YbF: Huge effective field  E Parpia Quiney Kozlov Titov

2nd advantage of YbF: No coupling   v  E to motional magnetic field and internuclear axis is coupled to E E     E  = 0 no motional systematic error electron spin is coupled to internuclear axis  Yb + F-F-

1500K heater Mo crucible YbF beam mirror probe laser PMT Yb and AlF 3 mixture Forming and probing a YbF beam

The A-X 0-0 band bandhead at nm 174 P(8) 174 Q(0) 174 P(9) 174 Q(1) P(8) 174 Q(0) 174 P(9) 174 Q(1) GHz P(9) 174 Q(0) 172 P(8)

| -1  | +1  | 0  The lowest two levels of YbF in an electric field E -d e  E +d e  E Goal: to measure the splitting 2d e  E X 2  + (N = 0,v = 0) F=1 F=0 170 MHz

Interferometer to measure 2d e  E Phase difference = 2 (  B B+d e  E)T/  E B Pump A-X Q(0) F=1 0 | -1  | +1  | 0  Split | -1 | MHz  pulse Probe A-X Q(0) F=0 0 ? Recombine 170 MHz  pulse

B and E 1.5 m The Sussex molecular beam beam oven pump split recombine detect PMT

Part of the optical setup

The interferometer fringe Interference signal (kpps) Magnetic field B (nT) Phase difference = 2(  B B+d e  E)T/ 

Measuring the edm Applied magnetic field Detector count rate E B0B0 -E  = 4d e  ET/  -B 0  4d e  ET/ 

E = 8 kV/cm B = 6 nT T coherence ~ 1 ms First YbF result: PRL 89, (2002) background fringe height coherence time d e (24 hrs data) 150kHz 1.5 kHz 1.5 ms < e cm Effective field = 13 GV/cm Limited by counting statistics Systematic error eliminated….

PMT dye laser 550 nm Supersonic YbF beam 10 bar Ar solenoid valve targetskimmer YAG laser 1064 or 532 nm 20 mJ in 10 ns delay generator scan Labview control and DAQ

Laser offset frequency (MHz) 172 P(8) 176 P(9) 174 Q(0) 1500K thermal source 3  10 5 useful molecules per second Laser offset frequency (MHz) 174 Q(0) 172 P(8) 176 P(9) 10K supersonic source 3  10 7 useful molecules per second

Possible experiment with trapped molecules supersonic source decelerator pumpsplit trap  ~ 1s E B recombineprobe interferometer

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

d(muon)  7× Current status of EDMs d(neutron)  6× d(proton)  6× YbF expt cold molecules d(electron)  1.6×10 -27

Conclusion EDM measurements (especially cold molecules) 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