Electric Dipole Moments of Fundamental Particles

Yannis K. SemertzidisBrookhaven National Lab

SIGHAD03Pisa, 8-10 October 2003

•Motivation•Experimental Techniques•Prospects•New Method•Summary

A Permanent EDM Violates both T & P Symmetries:

+

-

T-Violation CP-Violation(Could Explain Matter-Antimatter Asymmetry of Universe)

+

-

+

-T

P

CPT

EDM Searches are Excellent Probes of Physics Beyond the SM:

1. One CP-Violating Phase (CKM), Needs loops with all quark families for a non-zero result (Third Order Effect).

2. No Coupling to r.h. Fermions

SM:

1. 42 CP-Violating Phases, Needs one loop for a non-zero result (First Order Effect).

2. There is Coupling to r.h. Fermions

SUSY:

la Fortson

Current EDM Limits

• Neutron: n (-7.0<dn<5.0)10-26e·cm (90%CL) PRL 82, 904 (1999)

• Paramagnetic Atoms or Molecules, 205Tl: electron |de| < 1.610-27e·cm (90%CL)

PRL 88, 071805 (2002)

• Diamagnetic Atoms, 199Hg: |d(199Hg)| < 2.110-28e·cm (95%CL)

PRL 86, 2505 (2001)

“More Theoretical Models have been killed by the EDM Experiments than any other Experimental Method”

EdBdtsd

Experimental Methods

+-

Small Signal

Carrier Signal

Compare the Zeeman FrequenciesWhen E-field is Flipped:

dE421

la Fortson

la Fortson

la Fortson

d(muon) < 710-19

Left-Right

10-20

10-22

10-24

d e.cm

MultiHiggs SUSY

Electro-magnetic

neutron:electron:

1960 1970 1980 1990 2000 2010 2020 2030

10-28

10-29

Current status of EDMs

d(electron) < 1.6 10-

27

d(neutron) < 6 10-

26

d(proton) < 6 10-23

la Sauer

d(199Hg) < 2.1 10-28

Future Prospects:

• Neutron: Ultra-Cold Neutrons & Polarized 3He stored together in a superfluid 4He. 100-1000 within 5-years, S.K. Lamoreaux et al.

• Electron: YbF Ultra-cold molecules. ~1000 within ~5-years, B.E. Sauer et al.

• Electron: PbO*, ~1000 within 3-years, ~10 within 1-year, D. DeMille et al.

It’s a Horse Race!

Where is the EDM?

• Neutron?

• Electron?

• Muon (2nd Generation)?

• T-odd Nuclear Forces (199Hg)?

We don’t Know!

Muon and Deuteron Electric Dipole Moments in Storage Rings

• Revolutionary New Way of Probing EDMs.

EdBdtsd

Spin Precession in g-2 Ring(Top View)

Bmeaa

Momentumvector

Spin vector

Spin Precession in EDM Ring(Top View)

0a

Momentumvector

Spin vector

The muon spin precesses vertically (Side View)

BVdEddtsd

B

The muon spin precesses vertically (Side View)

BVdEddtsd

B

Radial E-field to Cancel the g-2 Precession

• Radial E-Field: 2aBcER

The method works well for particles with small anomalous magnetic moment a, e.g. Muons (a = 0.0011), Deuterons (a = -0.143), etc.

cEaBa

me

a

11

2

Predictions in Specific Models

The predicted value for the electron is 10 times lessthan the current experimental limit.

50 effect at 10-24 ecm Exp. Sensitivity!

Parameter Values of Muon EDM Experiment

• Radial E-Field:• E=2MV/m• Dipole B-field: B ~ 0.25T , R ~ 10m• Muon Momentum:

• Need NP2=1016 for 10-24e.cm. Muon EDM LOI: (http://www.bnl.gov/edm) to J-PARC, <one year of running.

• F. Farley et al., hep-ex/0307006

2aBcE

5 MeV/c,500 P

Deuteron EDM Signal:

• Radial E-Field:

Rd

R

EadaBdc

BcEddtsd

1

,2 aBcaBcER for γ~1

e.g. for ER = 3.5MV/m, d = 10-27e·cm; ωd = 0.4µrad/s

Sources of Deuteron Systematic Errors:

• Out of Plane Electric Field

• Tensor Polarization (not a Problem-Smaller is Better)

Effect of Vertical Component of E0)( vv ruBEeF

cE

uEBr

vv

cEB

cEBB

cEBcBEE

Bmeg

zr

zrr

zrrzz

r

**

*

*

0

2

EcE

meg

cE

meg

22

v

22

• Deuterons β=0.2, γ=1.02, ω=13105 θE rad/s

Effect of Vertical Component of E• Clock Wise and Counter-Clock Wise Injection:

Background: Same Sign Signal: Opposite Sign

• Protons β=0.15, γ=1.01, ω=115105 θE rad/s• Deuterons β=0.2, γ=1.02, ω= 13105 θE rad/s• Muons β=0.98, γ=5, ω= 2105 θE rad/s

• Other Diagnostics Include Injecting Forward vs Backward Polarized Beams as well as Radially Pol.

Parameter Values of a Deuteron EDM Experiment

• Radial E-Field:

ER=3.5MV/m

• Dipole B-field: B~0.13T; Ring Radius: R~32m

• Deuteron Momentum:• YkS et al., hep/ex-0308063

2aBcER

5.0 GeV/c, 1 dP

Deuteron Statistical Error:

TotcRpd fTNAPaE

a2

2

15.6

p : Polarization Lifetime (Coherence Time)A : The left/right asymmetry observed by the polarimeterP : The beam polarizationNc : The total number of stored particles per cycleTTot: Total running timef : Useful event rate fractionER : Radial electric field

Coherence Time Limitations:• E, B field stability

• Multipoles of E, B fields

• Vertical (Pitch) and Horizontal Oscillations

• Finite Momentum Acceptance ΔP/P

At this time we believe we can do p~3s

Deuteron Statistical Error:

TotcRpd fTNAPaE

a2

2

15.6

p : 3s. Polarization Lifetime (Coherence Time)A : 0.3. The left/right asymmetry observed by the polarimeterP : 0.55. The beam polarizationNc : 1011d/cycle. The total number of stored particles per cycleTTot: 107s. Total running timef : 0.1. Useful event rate fractionER : 3.5MV/m. Radial electric field

cme103 28 d

Possible Locations for a Deuteron EDM Experiment:• Brookhaven National Laboratory

• KVI/The Netherlands

• Indiana University Cyclotron Facility

Proposal Early Next Year…

Deuteron EDM to 10-27 ecm Sensitivity Level is 100 times better than 199Hg

• T-odd Nuclear Forces: dd =210-22 ξ e·cm with the best limit for ξ<0.5 10-3 coming from the 199Hg EDM limit (Fortson, et al., PRL 2001), i.e. dd < 10-25 e·cm.

(Sushkov, Flambaum, Khriplovich Sov. Phys. JETP, 60, p. 873 (1984) and Khriplovich and Korkin, Nucl. Phys. A665, p. 365 (2000)).

dd = dp + dn (I. Khriplovich)

It Improves the Current Proton EDM Limit by a Factor of ~100,000 and a Factor 60-100 on Neutron.

Possible Improvements:

• Higher ER Fields: 14MV/m with gas to slow down free electrons.

• Longer Storage Time than 3s while Maintaining Polarization (Coherence Time).

We Need to Study

• Target and Polarimetry (deuteron case)

• E-field Directional Stability

• Beam and Spin Dynamics

Electric Dipole Moment Searches:

• Exciting Physics, Forefront of SUSY Search.

• Revolutionary New Way of Probing EDMs.

• Sensitive EDM Experiments will bring the Next Breakthrough in Elementary Particle Physics.

Summary