Electric dipole moment searches E.A. Hinds Birmingham 11 th July 2011 Centre for Cold Matter Imperial College London

YbF atom/molecule level EDM: from particles to atoms and molecules 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 ~

P. Harris IoP 2011 Measurement principle BE BB Measure Larmor spin precession freq in parallel & antiparallel B and E fields d makes precession faster... Reverse E relative to B, look for freq shift.... or slower.

Pulsed YbF beam Pump A-X Q(0) F=1 Probe A-X Q(0) F=0 PMT 3K beam F=1 F=0 rf pulse B HV+ HV- eEDM in practice (Imperial) Ch 15 Cold Molecules, eds. Krems, Stwalley and Friedrich, (CRC Press 2009)

P. Harris IoP 2011 nEDM in practice N S Magnetic shielding Storage cell Magnet & polarizing foil Ultracold neutrons (UCN) UCN detector Approx scale 1 m Magnetic field coil B High voltage lead E /analysing foil

Status of eEDM and nEDM d e = (-2.4  5.7  1.5) × e.cm 68% statistical systematic - limited by statistical noise New eEDM result – YbF – Hudson et al. (Nature 2011) Previous eEDM result - Tl atoms d e < 2.0 × e.cm with 90% confidence Regan et al. (PRL 2002) Nataraj et al. (PRL 2011) d e < 1 × e.cm with 90% confidence d n < 3 × e.cm with 90% confidence Current upper limits

Left - Right MSSM  ~  Multi Higgs MSSM  ~ eEDM (e.cm) Imperial eEDM starting to explore this region Standard Model d e < 1.0 x e.cm Imperial eEDM (2011) Excluded region e.g. Pospelov and Ritz arXiv:hep-ph/ (2005)

P. Harris IoP 2011 Constraints on SUSY parameters Pospelov & Ritz, hep-ph/ M SUSY = 500 GeV tan  = 3 e

P. Harris IoP 2011 SUSY again Lebedev et al., hep-ph/ n Tl YbF (2011) n (2006)

Where do we go from here? nEDM Better polarisation Higher E field Longer spin coherence time More neutrons 10 x better CryoEDM eEDM Better field control Longer spin coherence time More YbF molecules 10 x better CryoYbF

Cryogenic YbF experiment (Imperial) YbF beam YAG ablation laser 3K He gas cell Yb+AlF 3 target New J. Phys (2009) Physical Review A (2011) S. M. Skoff et al. Uses new molecular beam source

eEDM prospects with new source 15  more molecules 3  longer interaction time => access to few x e.cm range => 10  better signal:noise ratio will improve systematics as well as statistics

garnet E squid magnetometer GGG (LANL), GIG (Amherst) Gadolinium Garnets Huge number of electrons Other electron EDM searches E Cs atoms Fountain (LBL), Trapped (Penn State), Trapped (Texas) Long coherence time Molecules Large effective E field PbF beam (Oklahoma) similar to YbF Metastable ThO beam (Yale/Harvard) similar to YbF Trapped HfF + ions (JILA) 1 molecule; very long coh.time none competitive with YbF in the immediate future

P. Harris IoP 2011 Cryogenic nEDM experiment Neutrons produced, transported, & stored. Need lower losses. 10 kV/cm applied; aiming for kV/cm Polarisation observed, but must improve Detector efficiency set to improve significantly Magnetic field stability to be improved by factor 1000 Sussex, RAL, Oxford, ILL,Kure

P. Harris IoP 2011 Other nEDM experiments PSI (50 people) aim by 2015 ORNL (90 people) construction 2017; aims eventually for e.cm ILL: Russian group. Reinstating system from 1990 measurement. Perhaps e.cm eventually. FRM, Munich: hoping to install UCN source. Nothing firm yet Masuda, Japan: observed resonance, but very low stats. Move to TRIUMF?

P. Harris IoP and other particles Muon EDM: from g-2 (7E-19 e.cm; proposed upgrades could reach ~ e.cm by ~2020) Deuterium EDM: similar principle (claimed potential reach ~ e.cm) Tau weak dipole moment – look for CP- odd observables in diff. x-sec at Z res. (6E-18 e.cm from LEP data) Sensitivity to physics BSM depends on source of CPv

Conclusions These place strong constraints on CP-violation beyond std model d e < 1 × e.cm d n < 3 × e.cm Current upper limits UK leads the world in both Will continue to do so if projects funded.