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Electric Dipole Moments

Electric Dipole Moments. EDMs and BSM (Beyond Standard Model) physics New CP violation - Baryogenesis ? How to identify origin of new CP violation Need data from multiple species Summary of experiments Short overview Sensitivities Focus on experiments potentially at Fermilab.

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Electric Dipole Moments

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  1. Electric Dipole Moments • EDMs and BSM (Beyond Standard Model) physics • New CP violation - Baryogenesis? • How to identify origin of new CP violation • Need data from multiple species • Summary of experiments • Short overview • Sensitivities • Focus on experiments potentially at Fermilab Brad Filippone PXPS12 - 6/15/12

  2. Why EDMs? (high on some people’s lists…) “…it may be that the next exciting thing to come along will be the discovery of a neutron or atomic or electron electric dipole moment.” S. Weinberg arXiv:hepph/9211298 Dec. 2011

  3. Why EDMs? CP Violation and the Matter/Antimatter Asymmetry in the Universe • Sakharov Criteria • Baryon Number Violation • CP & C violation • Departure from Thermal Equilibrium • Standard Model CP violation is insufficient • Must search for new sources of CP • B-factories, LHC, Neutrinos, EDMs

  4. Status of Electroweak Baryogenesis • Appeared to be “ruled out” several years ago • First order phase transition doesn’t work for Standard Model with MHiggs > 120 GeV • Recent work has revived EW baryogenesis • First order phase transition still viable • Resonance in MSSM during phase transition with new gauge degrees of freedom M. Carena, M. Quiros, A. Riotto, I. Vilja and C. E. Wagner, Nucl. Phys. B 503, 387 (1997) Li, Profumo, Ramsey-Musolf : arXiv:0811.1987 Cirigliano, Li, Profumo, Ramsey-Musolf: JHEP 1001:002,2010 a Note: Leptogenesis is also possible

  5. EDMs in Quantum Picture– Discrete Symmetries Charge Conjugation: Parity: Time Reversal: C P T Non-Relativistic Hamiltonian + + - J m - + - 123 123 C-even P-even T-even C-even P-odd T-odd B - + - - + - d Non-zero d violates T and CP (Field Theories generally preserve CPT) - - + E

  6. g W d,s,b Origin of elementary EDMs • Standard Model EDMs are due to CP violation in the quark weak mixing matrix CKM (e.g. the K0/B0-system) but… • e- and quark EDM’s are zero at 1 AND 2 loops • Need at least three “loops” to get EDM’s (electron actually requires 4 loops!) • Thus EDM’s are VERY small in standard model Neutron EDM in Standard Model is ~ 10-31 e-cm (=10-18 e-fm) Experimental neutron limit: < 3 x 10-26 e-cm

  7. CP How to characterize EDMs… • Elementary hadronicEDMs are from • qQCD(a special parameter in Quantum Chromodynamics – QCD) • or from the quarksthemselves Weinberg 3-gluon term qQCD quark color EDM (chromo-EDM) e-,quark EDM

  8. Origin of elementary EDMs Electric dipole moments as probes of new physics Maxim Pospelov, Adam Ritz Annals Phys.318:119-169,2005 Clearly, if EDM is found, we will need multiple systems to identify the origin of new CP violation (e.g. ….

  9. Example Calculation of EDMs Considerable model dependence remains in above

  10. Why do we care? • It characterizes the underlying theory • Origin of new CP violation influences its role in Electroweak Baryogenesis • e. g. qQCD much less effective in creating matter-antimatter asymmetry since effect on vacuum is suppressed

  11. Is there a “natural” source for new CP violation & EDMs? • New physics (e.g. SuperSymmety = SUSY) often has additional CP violating phases in added couplings • New phases: (fCP) should be ~ 1 (why not?) • Contribution to EDMs depends on masses of new particles Chargino Gluino • dn~ 10-24 e-cm x sinjCP(1 TeV/MSUSY)2 Note: experimental limit: dn < 0.03 x 10-24 e-cm Standard Model Prediction: dn < 10-31 e-cm

  12. Possible impacts of non-zero EDM V. Cirigliano et al., http://arxiv.org/abs/hep-ph/0603246 and private communication • Must be new Physics • Sharply constrains • models beyond the • Standard Model • (especially with • LHC data) • May account for matter- • antimatter asymmetry of • the universe LHC dn= 4 x 10-28 e-cm Higgs superpartner mass dn Large Hadron Collider gauge boson superpartner mass Much more EDM theory to come: S. Gardner, K. Blum, E. Mereghetti , E. Shintani, T. Bhattacharya

  13. Experimental EDMs • Atomic/Molecular EDMs for electron EDM (paramagnetic systems = unpaired electrons) • Atomic/Molecular EDMs for quark chromo-EDM (diamagnetic systems = paired electrons) • Storage ring experiments for muon and proton • Ultra-Cold neutron traps for neutron EDM

  14. Experimental EDMs • Present best limits come from atomic systems and the free neutron • 205Tl & YbF are primarily sensitive to de • 199Hg and the free neutron are primarily sensitive to • Future best limits may come from • Polar Molecules (ThO) • Liquids (129Xe) • Solid State systems (high density) • Storage Rings (Muon, Deuteron, Proton, 3He) • Radioactive Atoms (225Ra, 223Rn, 211Fr) • New Technology for Free Neutrons • PSI, ILL, SNS,FRMII,RCNP/TRIUMF

  15. Present n-EDM limit Proposed n-EDM limit 1997 “n-EDM has killed more theories than any other single experiment”

  16. Experimental EDM Summary Searching for New Physics beyond the Standard Model in Electric Dipole Moment Takeshi Fukuyama arXiv:1201.4252v3 [hep-ph] + p! Next Gen exps. : Improve sensitivity x10  x100

  17. What is the precision in EDM measurement? Using Uncertainty Principle: Precise energy measurement requires long measurement time, giving But must include counting statistics Often limited by spin coherence time or particle lifetime (intermittent beam possible) E – Electric Field tm– Time for measurement m – total # of measurements N – Total # of counts/meas. Ttot– Total measurement time Sensitivity:

  18. Often use Measurement of frequency • Best neutron limit used Ramsey separated-oscillatory field technique • Inject n • Rotate and precess for Dt • Spin rotates by wDt • Measure how many nh vs. ni

  19. Careful magnetometry is essential ! (systematics, systematics, systematics) ILL neutron EDM (Baker, et al) 10,000 x EDM limit E-field reversals Raw Frequency Corrected by199Hg Magnetometer

  20. EDMs in the Context of Project X • What experiments are possible at Fermilab? • Proton EDM in storage ring (Y. Semertzidis- tomorrow) • Uses infrastructure, expertise & high currents at Fermilab • Radioactive atom EDM (J. Nolen & M. Dietrich-tomorrow) • Isotope Separator On-Line (ISOL) production facility • Neutron EDM • High densities of Ultra-Cold Neutrons via spallation • … (T. Chupp- tomorrow)

  21. Storage Ring Proton EDM p = 0.7 GeV/c • Radial Electric Field stores protons • Long coherence time possible >103s • B = vxE causes longitudinal spin to precess in horiz. plane • At magic energy spin stays long. • EDM causes spin to precess into vertical plane • Polarimeter detects vertical spin component • Counter rotating p-beams monitor systematics • Vertical displacement of beams monitors false EDM (e.g. radial B-field)

  22. The proton EDM ring Statistical sensitivity potentially 10x better than new neutron EDM exps. YannisSemertzidis, BNL

  23. What’s needed for pEDM? • Infrastructure for small-scale (~ 100 m diam.) storage ring • HV & proton storage ring technology • High intensity low-energy proton beams

  24. Atomic EDMs • Schiff Theorem • Neutral atomic system of point particles in Electric field readjusts itself to give zero E field at all charges With E-field +Q -Q E

  25. But … • Magnetic and finite size effects can break the symmetry • Enhancement for de in paramagnetic atoms (unpaired electrons) • Suppression for hadronic EDMs in diamagnetic atoms (paired electrons) – but “Schiff Moment” is non-zero (due to finite size of nucleus) Thus dTl ~ -10 Z3a2de~ -585 de & |de| < 1.5 x 10-27 e-cm for 199Hg

  26. But,but, … Enhanced Atomic EDM via Octupole deformations p Diamagnetic Paramagnetic Big enhancements possible compared to e.g. 199Hg Note: Polar Molecules also have huge enhancement factors Small applied E-field (100V/cm) leads to huge local fields (100GV/cm)

  27. EDM in RnSpokesmen: Timothy Chupp2 and Carl Svensson1Sarah Nuss-Warren2, Eric Tardiff2, Kevin Coulter2, Wolfgang Lorenzon2, Timothy Chupp2John Behr4, Matt Pearson4, Peter Jackson4, Mike Hayden3, Carl Svensson1University of Guelph1, University of Michigan2, Simon Fraser University3, TRIUMF4 N2 pushes Rn into cell TRIUMF Neutralize and cool down Rn Rn + Rb B  E fields Analyze Rn Rn + Rb exchange g ray anisotrpy laser probing

  28. Oven: 225Ra (+Ba) Zeeman Slower EDM probe Optical dipole trap An Experiment to Search for EDM of 225RaI. Ahmad, R. J. Holt, Zheng-Tian Lu, E. C. Schulte, Physics Division, Argonne National Laboratory • Status and Outlook • First atom trap of radium realized; • Guest et al. PRL (2007) • Search for EDM of 225Ra in 2010 • Systematic improvements will follow 225Ra Nuclear Spin = ½ Electronic Spin = 0 t1/2 = 15 days Magneto-optical trap • Why trap 225Ra atoms • Large enhancement: • EDM (Ra) / EDM (Hg) ~ 200 – 2,000 • Efficient use of the rare 225Ra atoms • High electric field (> 100 kV/cm) • Long coherence times (~ 100 s) • Negligible “v x E” systematic effect

  29. What’s needed for radioactive atom EDM? • High intensity ISOL-type facility to separate isotopes with lifetimes ~ minutes to days • ~ 1 GeV proton spallation facility • Thermal extraction • Separator and neutralizer • Medium-scale AMO type lab space • Potential for > 100-1000 x radioactive atom yield

  30. Neutron EDM Worldwide

  31. Essentially all sensitive nEDM use Ultra-Cold Neutrons (UCN) • What are UCN ? • Very slow neutrons (v < 8 m/s ’l > 500 Å ) that cannot penetrate into certain materials • Governed by low-energy neutron-nucleus scattering length

  32. Higher Density UCN Sources • Use non-equilibrium system (aka Superthermal) • Superfluid4He • (T<1K minimizes n-reheating) (neutron) 11K (9Å) incident neutron produces phonon & becomes UCN • Solid deuterium (SD2) • Gollub& Boning(83) • Faster UCN production but more absorption • Small re-heating if T < 6K

  33. LANSCE SD2 UCN Source UCN Detector 0.8 GeV proton beam (~20 n/proton) at 5 mA average current Bottle 1000 800 UCN valves 600 400 200 0 0 5 10 15 20 25 Time (sec)

  34. New World Record UCN Density Previous record for bottled UCN = 41 UCN/cm3 (at ILL) Measurements of Ultra Cold Neutron Lifetimes in Solid Deuterium [PRL 89,272501 (2002)] Demonstration of a Solid Deuterium Source of Ultra-Cold Neutrons [Phys. Lett. B 593, 55 (2004)]

  35. Arguaby most ambitious new n exp. is nEDM@SNS • Load collection volume with polarized 3He atoms • Transfer polarized 3He atoms into the measurement cell • Illuminate measurement cell with polarized cold neutrons to produce polarized UCN • Apply a p/2 pulse to rotate spins perpendicular to B0 • Measure precession frequency • Remove reduced polarization 3He atoms from measurement cell • Flip E-field & Go to 1.

  36. 2 Independent Measurements • Capability for using two EDM measurement techniques is built into the apparatus. • Frequency measured via n-3He captureduring free precession • Polarized 3He as “co-magnetometer” (d3 <<< dndue to e- screening) • Detect precession of 3He magnetization via SQUIDS - directly measures variation of B-field averaged over measurement cells • Spin Dressing • RF field can make precession of 3He and n equal (at zero E-field) to minimize sensitivity to background B-fields 2 techniques provide critical cross-check of EDM result with different systematics and risks Statistical sensitivity < 4 x 10-28 e-cm

  37. What’s needed for nEDM? • Proton spallation target coupled to cold or “ultra-cold” moderator • 1 GeV proton spallation target with cold moderator & extracted, optimized cold neutron beam on SF LHe or • 1 GeV proton spallation target with Ultra-Cold moderator with extracted UCN “beam” • SuperfluidLHe or Solid D2 • Medium-size NP type lab space • Proven, statistics-limited experiment • Potential for x 50 higher UCN densities Beam for SNS type UCN source may be compatible with cold neutron source for n-n oscillation exp.

  38. Summary • Observation of CP-violating EDM in next decade would be NP (New Physics) • Single observation is insufficient to characterize origin of CP • Many experiments may be statistically limited and could benefit from Project X • pEDM, Radioactive atoms (Ra, Rn, Fr), nEDM

  39. Backup Slides

  40. EDM Experiment at SNS

  41. Simplified Measurement of EDM E-field 1. Inject polarized particle 2. Rotate spin by p/2 3. Flip E-field direction 4. Measure frequency shift B-field Must know B very well

  42. New Technique for n-EDM E-field • Inject polarized neutron • & polarized 3He 2. Rotate both spins by 90o 3. Measure n+3He capture vs. time (note: sih>>shh) 4. Flip E-field direction B-field 3He functions as “co-magnetometer” Since 3He EDM << nEDM due to atomic e-screening

  43. “Dressed” Spins • By applying a strong non-resonant RF field, the effective precession frequencies can be modified or “dressed” • For particular values of the dressing field, the neutron and 3He precession frequencies are equal

  44. Systematic Effects in nEDM • Variation of B-field • Co-magnetometer cancels B-field variations • Leakage currents from Electric Field • These may produce heating that changes with E-field (must be less than picoAmps) • effects are the largest sources of systematic error in previous ILL exp. • BE = v x E g changes precession frequency • Adds geometric phase when combined with B gradients

  45. Systematic Controls in SNSexperiment • Highly uniform E and B fields • Superconducting Magnetic Shield • Two cells with opposite E-field • Ability to vary influence of B0 field • via “dressed spins” • Study dependence on |B|, B, B-gradients & 3He density • Control of central temperature • Can vary 3He diffusion which changes geometric phase effect on 3He

  46. Spallation Neutron Source (SNS) at ORNL 1 GeV proton beam with 1.4 MW on spallation target

  47. If Neutron had degenerate state it would not violate T or CP u dd dd u But some molecules have HUGE EDMs! H20: d = 0.4 x 10-8 e-cm NaCl: d= 1.8 x 10-8 e-cm NH3: d = 0.3 x 10-8 e-cm But NH3 EDM is not T-odd or CP-odd since Ground state is actually a superposition

  48. Summary of Experimental Components • Cold Neutron Beam • Cryogenic system (77K, 4K, .35K) • Polarized 3He System • Must inject, transport and remove 3He • With minimal polarization loss • With high efficiency • Magnets and Magnetic Shielding • Central Detector • HV, Light collection, SQUID monitors, … Technically challenging!

  49. The nEDM Collaboration Mix of Low Temp, Atomic, Nuclear & Particle Physicists Engineers

  50. Example of future Neutron EDM Sensitivity

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