Philip Harris EDM Experiments PPAP, Birmingham 15/7/09

P. Harris PPAP 15/7/09 Electric Dipole Moments EDMs are P, T odd Complementary study of CPv CPv mechanism not understood Need to test with other systems than K, B Clean system background free: SM predicts tiny EDMs, other models typically 10 6 larger Tight constraints on models of new physics SM can’t accommodate baryon asymmetry of U. E +

P. Harris PPAP 15/7/09 Standard Model EDM EDMs are zero-momentum limit of fermion-fermion-photon 3- point function: SM CPv related to single phase in CKM,  flavour change EDM is flavour conserving CPv,  “flavour change squared” In fact  3 loops; v. suppressed

P. Harris PPAP 15/7/09 Strong CP problem d n ~  e.cm   < 2  rads CPv phase  QCD in strong int. induces neutron EDM Why is  so small? Peccei-Quinn: Axions?

P. Harris PPAP 15/7/09 SUSY breaking introduces new CPv phases EDMs appear at 1-loop level For superpartner masses ~few 100 GeV & large phases, predicted nEDM is x too large – SUSY CP problem Supersymmetry

P. Harris PPAP 15/7/09 EDM candidates Neutron: Intrinsic EDM from CPv field thy (SUSY, L-R, add’l Higgs...); strong CPv Electron: Intrinsic EDM from CPv field thy Atomic: P, T violating nucleon-nucleon or nucleon-electron interaction (inc. strong CPv) - all sensitive to different physics beyond SM - each gives new window on CPv - must measure all to distinguish between CPv models

P. Harris PPAP 15/7/09 Measurement principle B0B0 E = + h/2 = - h/2 h (0) h (  ) h (  ) B0B0 B0B0 E Energy resolution typically< eV Use NMR on neutrons or atoms in B, E fields. Look for change in Larmor frequency induced by reversal of E: atomic clock

P. Harris PPAP 15/7/09 History: nEDM Factor 10 every 8-10 years CryoEDM Current limit |d n | < 2.9 x e.cm (90% CL) C.A. Baker et al., Phys. Rev. Lett. 97, (2006); hep-ex/ Nearly 500 cites

P. Harris PPAP 15/7/09 CryoEDM More neutrons N Higher electric field E Better polarisation  Longer NMR coherence time T 100-fold improvement in sensitivity C.f. room-temp vacuum, liquid He offers: ~25 people

P. Harris PPAP 15/7/09 CryoEDM overview Neutron beam input Transfer section Cryogenic Ramsey chamber

P. Harris PPAP 15/7/09 Current status Commissioning underway – all components shown to work (but need improvement) - OsC signoff Cryogenics are old and cause problems! B shielding not yet optimal, and electric field needs to increase; but we know how Finance difficult – costs in € - and staffing levels very tight (no ILL support) First results ~ at ~3E-27 level

P. Harris PPAP 15/7/09 Future plans : ILL wants to move expt to 6x brighter beamline Will need small increase in personnel, esp. during dismantling/reconstruction Potential new collaborators from EPSRC-land? Aim to submit proposal this autumn

P. Harris PPAP 15/7/09 Other nEDM expts: (a) SNS Concept by Golub & Lamoreaux, 1994 Large US collaboration: ~90 people, 20 institutions Anticipated sensitivity ~ e.cm Latest estimate: will start taking data in 2016

P. Harris PPAP 15/7/09 Other nEDM expts: (b) PSI 50 people, 15 insts. spallation target, D 2 O moderator apparatus tested for few ILL, now moved to PSI first neutrons late early 2010 sensitivity perhaps <1E-26 by ~2012

P. Harris PPAP 15/7/09 Other nEDM expts: (c) PNPI/ILL Serebrov group: tried to build multi-chamber spectrometer. n density not adequate Installed old (1990) PNPI apparatus Sensitivity ~1x e cm after ~2 years

P. Harris PPAP 15/7/09 Other nEDM expts... Japan (Masuda) – have achieved UCN production in LHe. Germany - talk of proposal using solid deuterium UCN source at FRM, Munich, but no immediate plans Solid-state using crystal diffraction: Incident plane wave split along/between lattice planes; components see different E fields. Sensitivity ~few x ecm now, perhaps ~ few x eventually

P. Harris PPAP 15/7/09 Summary of leading nEDM expts Group# peopleAnticipated sensitivity (ecm) By... UK: CryoEDM~25~3E CryoEDM (new beamline) ~30? * ~3E ?? SNS-EDM~90<1E-28?>2020?? PSI~50~1E PNPI/ILL~10-20?~1E * my guess

P. Harris PPAP 15/7/09 Electron EDM Standard Model eEDM (e.cm) Left - Right MSSM  ~  Multi Higgs MSSM  ~ result YbF molecule 2002 result Tl Atom 5-year YbF programme e.cm

P. Harris PPAP 15/7/09 Fluorescence Time of flight (ms) Time-of-flight profile The YbF eEDM experiment Pulsed YbF beam Pump A-X Q(0) F=1 Probe A-X Q(0) F=1 PMT 3K beam F=1 F=0 rf pulse B HV+ HV- Scanning the B-field B (nT) Fluorescence

Why heavy polar molecules are so sensitive E electric field de de  amplification (Sandars) atom or molecule containing electron For more details, see E. A. Hinds Physica Scripta T70, 34 (1997) Interaction energy -d e  E  F P F P Polarization factor ~1 Structure-dependent relativistic factor YbF ~ 26 GV/cm !

P. Harris PPAP 15/7/09 Leading alternative approaches to eEDM Atomic Thallium beam (Berkeley) Current world limit, but has gone as far as possible. Ultracold Cs in a lattice (Penn State). Probably 10 years from measurement. Solid state Spins in ferroelectric solids (Yale) Macroscopic sample. Low noise. Previous solid expts. had huge systematics potential accuracy unknown. Molecular YbF beam (Imperial) World-leading result in prep 1× e cm over 5 yrs. PbO* cell (Yale) Ending because of systematic errors. ThO beam (Harvard/Yale) “5 yrs from 1 st result aiming at e cm” PbF beam (Oklahoma) Just starting - “10 years from measurement” HfO + (Boulder) trap “Serious measurement far away”. Might reach 1× e cm

P. Harris PPAP 15/7/ Hg EDM Optically pumped 199 Hg atoms precess in B & E fields, modulating absorption signal. Multiple cells remove effects of B drift. Result: d( 199 Hg) < 3 x e cm Provides good limit on CPv effects in nuclear forces, inc.  QCD “Confirms” d n <6x ecm (our 1999 result).

P. Harris PPAP 15/7/09 Sidelines Muon EDM: 7x e.cm from g-2 (Suggestion to do similar on small ring, perhaps PSI: e.cm) Deuterium EDM: same principle; ~ e.cm achievable? Tau weak dipole moment: CP-odd observables in diff. x-sec at Z res., 6x e.cm from LEP data Sensitivity to physics BSM depends on source of CPv

P. Harris PPAP 15/7/09 Conclusions EDM physics of fundamental importance for CPv & BSM; complementary to accelerator PP Niche area but worldwide interest/competition UK currently leads the world with nEDM & (very shortly) with eEDM, despite tight resources 5-10 year plans to improve limits up to 2 orders of magnitude

P. Harris PPAP 15/7/09 spare slides

P. Harris PPAP 15/7/09 EDM measurement technique n or e spin vector frequency reference initial setup – systems in phase free Larmor precession (n, e in B and E fields) spin analysis: Phase diff. after long time t gives accurate frequency difference from reference clock Look for frequency change induced by reversal of E atomic clock

P. Harris PPAP 15/7/09 Electron EDM: Berkeley Final result: d e <1.6 x e.cm (systematics limited) Unpaired e - in neutral atom Pairs of Tl beams in opposite E fields Na beams as comagnetometer Up beam E field B field State preparation laser State analyser laser Down beam

P. Harris PPAP 15/7/09 UCN production in liquid helium 1.03 meV (11 K) neutrons downscatter by emission of phonon in liquid helium at 0.5 K Upscattering suppressed: Boltzmann factor e -E/kT means not many 11 K phonons present n = 8.9 Å; E = 1.03 meV Landau-Feynman dispersion curve for 4 He excitations Dispersion curve for free neutrons R. Golub and J.M. Pendlebury Phys. Lett. 53A (1975), Phys. Lett. 62A (1977)

P. Harris PPAP 15/7/09 Systematics B-field fluctuations Superconducting solenoid & shield will give much improved field shape and shielding SQUIDs give temporal variation (common-mode) Shielding not optimal at present: improvements foreseen Geometric phase n are ~40x less sensitive than Hg 1/B 2 : 5 x increase in B gives 25x protection overall 1000x improvement Other: Exv: 3E-29 e.cm Feedback from field coils: <1E-30 e.cm Electrostatic forces: < 1E-28 e.cm Leakage currents: 1 nA  5E-29 e.cm AC fields from HV: < 1E-29 e.cm Overall: no show-stoppers...

P. Harris PPAP 15/7/09 SM prediction

P. Harris PPAP 15/7/09 SUSY constraints – example Pospelov & Ritz, hep-ph/ M SUSY = 500 GeV tan  = 3

P. Harris PPAP 15/7/09 SUSY, cont’d Lebedev et al., hep-ph/

P. Harris PPAP 15/7/09 Ramsey method of Separated Oscillating Fields Free precession... Apply  /2 spin- flip pulse... “Spin up” neutron... Second  /2 spin-flip pulse 130 s 2 s

P. Harris PPAP 15/7/09 Ramsey resonance “2-slit” interference pattern Phase gives freq offset from resonance