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/
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:
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 + + -
123
123 m - + -
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. 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
~ e-cm (=10-18 e-fm) g
d,s,b W
Experimental neutron limit: < 3 x e-cm

7. How to characterize EDMs…
Elementary hadronic EDMs are from
qQCD (a special parameter in Quantum Chromodynamics – QCD)
or from the quarks themselves
qQCD
Weinberg
3-gluon term CP
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: ,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
System
Dependence n
dn ~ (3x10-16)qQCD + p
dp ~ (-3x10-16)qQCD + Tl
dTl ~ 585de - e(40GeV)CS
199Hg
dHg ~ (0.007x10-16)qQCD -
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
Gluino
Chargino
dn ~ e-cm x sinjCP(1 TeV/MSUSY)2
Note: experimental limit: dn < 0.03 x e-cm
Standard Model Prediction: dn < e-cm

12. Possible impacts of non-zero EDM
V. Cirigliano et al., 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 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. “n-EDM has killed more theories than any other single experiment”
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: v3
[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
Careful magnetometry is essential ! (systematics, systematics, systematics)
ILL neutron EDM (Baker, et al)
10,000 x EDM limit
E-field reversals
Raw Frequency
Corrected by 199Hg 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
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)
p = 0.7 GeV/c

22. Yannis Semertzidis, BNL
The proton EDM ring
Statistical sensitivity
potentially 10x better
than new neutron EDM exps.
Yannis Semertzidis, 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 e-cm
for 199Hg

26. Enhanced Atomic EDM via Octupole deformations
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 Rn Spokesmen: Timothy Chupp2 and Carl Svensson1 Sarah Nuss-Warren2, Eric Tardiff2, Kevin Coulter2, Wolfgang Lorenzon2, Timothy Chupp2 John Behr4, Matt Pearson4, Peter Jackson4, Mike Hayden3, Carl Svensson1 University of Guelph1, University of Michigan2, Simon Fraser University3, TRIUMF4
TRIUMF
N2 pushes
Rn into cell
Neutralize and cool down Rn
Rn + Rb
B  E fields
Analyze Rn
Rn + Rb
exchange
g ray
anisotrpy
laser
probing
211Rn (I=1/2; 15h)
223Rn (I=7/2; 23 m)
Rate
d (√day)
TRIUMF
2x109
6x10-29
1x107
2x10-27
RIA
1x1010 1
3x10-29
5x108
1x10-28

28. An Experiment to Search for EDM of 225Ra I. Ahmad, R. J
An Experiment to Search for EDM of 225Ra I. 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
Oven:
225Ra (+Ba)
Zeeman
Slower
Optical
dipole trap
EDM
probe
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 > x radioactive atom yield

30. Neutron EDM Worldwide Exp UCN source cell Measurement techniques sd
(10-28 e-cm)
ILL
CryoEDM
Superfluid 4He
4He
Ramsey technique for w
External SQUID magnetometers
Phase1 ~ 50 Phase 2 < 5
PNPI – ILL
ILL turbine
PNPI/Solid D2
Vac.
E=0 cell for magnetometer
Phase1<100
< 10
ILL Crystal
Cold n Beam
solid
Crystal Diffraction
< 100
PSI EDM
Solid D2
Ramsey for w, external Cs & 3He magnetom.Possible Xe or Hg comagnetometer
Phase1 ~ 50
Phase 2 < 5
SNS EDM
3He capture for w
3He comagnetometer
SQUIDS & Dressed spins
< 5
RCNP/TRIUMF
Small vol., Xe co-mag.
JPARC
Under Development
Munich FRMII
Room Temp. , Co-mag.
NIST
Crystal
Solid
R & D
~ 5 ?

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)
Superfluid 4He
(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 Bottle UCN valves
0.8 GeV proton beam (~20 n/proton) at 5 mA average current
1000
800
UCN
Detector
Bottle
UCN valves
600
400
200 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, (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 capture during free precession
Polarized 3He as “co-magnetometer” (d3 <<< dn due 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 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”
Superfluid LHe 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 SNS experiment
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. 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
If Neutron had degenerate state
it would not violate T or CP u dd
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
ILL
SNS
NUCN
1.3 x 104
4 x 105
|E|
10 kV/cm
70 kV/cm Tm
130 s
500 s
m (cycles/day)
270 30
sd (e-cm)/day
3 x 10-25
4 x 10-27

51. Why so many nEDM?? Science remains compelling even with LHC data
“PPAN was pleased to note that the consultation panel broadly confirmed the prioritisation order … The top priority projects (ATLAS, CMS, nEDM) were confirmed in this status and were graded alpha 5. “
Particle Physics, Astronomy and Nuclear Panel - UK
Superthermal UCN sources promise higher densities
Exciting opportunity for new/existing facilities
New = FRMII,JPARC,SNS; Existing = ILL,PSI,TRIUMF

52. Baryogenesis Plausibility Argument (GUTS Baryogenesis)
Consider very heavy boson X (MX ~ 1019 GeV)
Baryon number violation:
C & CP violation
Out of Thermal Equilibrium
If in Equilibrium then the reverse reactions
(e.g ) will smooth out any matter/antimatter excess

53. EDM from qQCD This is the strong-CP problem in QCD
qQCD should be naturally about ~ 1
This gives a neutron EDM of

54. EDM from qQCD Small qQCD does not provide any new symmetry for LQCD
Elegant solution is new symmetry (Peccei-Quinn symmetry) – new term in LQCD
Requires new pseudoscalar particle
No Axions observed yet
Extra dimensions might suppress qQCD
Remains an unsolved theoretical “problem”

55. Status of Experiment Active R&D efforts are underway
Encouraged by recent NSAC subcommittee
E.g. HV in Superfluid, Magnets and shielding, 3He transport
Demonstration of Electric Field strength is one remaining “Critical R&D”
Construction can begin after successful demonstration of Critical R&D
Cost Range: 40-50M$