Electric dipole moments: a search for new physics

E.A. Hinds

Manchester, 12 Feb 2004

Imperial College London

Fundamental inversions

C particle antiparticle

P position inverted

T time reversed

(Q -Q)

(r -r)

(t -t)

Symmetries

Weak interactions are not symmetric under P or C

normal matter - n, , - readily breaks C and P symmetry.

The combination CP is different

normal matter respects CP symmetry to a very high degree.

Time reversal T is equivalent to CP (CPT theorem)

normal matter respects T symmetry to a very high degree.

Electric dipole moment (EDM) breaks P and T symmetry

P -+

elementary particle +-

spin

edm

(P no big deal)

+- T +

-(CP big deal)

Two motivations to measure EDMs

EDM is effectively zero in standard modelbut

big enough to measure in non-standard models

direct test of physics beyond the standard model

EDM violates T symmetry

Deeply connected to CP violation and the matter-antimatter asymmetry of the universe

Left-Right

10-32

10-20

10-22

10-24

10-30

MultiHiggs SUSY

Standard Model

Electro-magnetic

10-34

10-36

10-38

Exp

erim

enta

l Lim

it o

n d

(e.

cm)

1960 1970 1980 1990

neutron:

electron:

2000

10-20

10-30

10-22

10-24

10-26

10-28

A bit of history

thallium

atom/moleculelevel

CP from particles to atoms (main connections)

nuclearlevel

NNNNSchiff

momentmercury

HiggsSUSY

Left/Right

StrongCP

field theoryCP model

GG

neutron

nucleonlevel

electron/quark level

de

dq

dcq

~

The Mercury EDM experiment

University of Washington, SeattleM.V. Romalis, W.C. Griffith, J.P. Jacobs, E.N. Fortson

Nuclear spin polarised 199Hg vapor in a double cell

h = B

+ dEE

- dE±

B

± measured optically

199 H

g E

DM

(10

-27 e

.cm

)

GSI992

Hg edm result: Phys. Rev. Lett. 86, 2505 (2001)

|dHg| < 2.110-28 e cm

E = 9 kV/cm

B = 1.5 T stable to 0.4 pT

Tcoherence ~ 100 s

Difference of precession frequencies gives 199Hg EDM

The Neutron EDM

Rutherford-Appleton LaboratoryD Wark, P Iaydjiev, S Ivanov, S Balashov, M. Tucker

Sussex UniversityPG Harris, JM Pendlebury, D Shiers, M van der Grinten, K Zuber, K Green, m Hardiman, P Smith, J Grozier, J Karamath

ILL

P Geltenbort

• Ultracold neutrons in a bottleprecess at frequency (nB dnE)/

• Reverse E to measure dn

OXFORD

H. KrausN Jelley

H Yoshiki

KURE

GSI992

Neutron edm result: Phys. Rev. Lett. 82, 904 (1999)

|dn|< 6.310-26 e cm

E = 4.5 kV/cm

B = 1 T

Tcoherence ~ 130 s

Hg co-magnetometer

(B is measured to 1 pT rms)

Aiming at 3 10-28 e.cm over next decade

Neutron: longer range plans

Helium (ILL, LANL)Inside the heliumHigher neutron densityHigher E field

New moderators using liquid helium or solid deuterium

Deuterium (PSI, TU-Munich)Outside the deuteriumHigher neutron densityBigger volume (fast moderation)

Implications of n and Hg for the theta parameter

gs2

32GG~

CP strong interaction

dn 10-16

610-10n n

p

×

induces neutron EDMBaluniCrewtherPospelov

Henley & HaxtonPospelov

induces mercury Schiff moment

N/

×N

dHg 1 10-18

210-

10

Something(Peccei-Quinn?)

makes very small!

Implications of Hg and nfor SUSY

quark electric dipole moments

dq q (F i5 ) q21

q q

gaugino

squark

quark color dipole moments

q q

g

gaugino

squark

dq q (gs Gi5 ) q21 c

2mqdq, dq ~ (loop factor) sin CP c

CP phase from soft breaking naturally O(1)

scale of SUSY breaking naturally ~200 GeV

naturally ~

du,d, du,d ~ 31024 cm naturallyc

n and Hg experiments give du< 2 1025

dd< 5 1026

du< 3 1026

dd< 3 1026

c

c

~ 100 times less!

CP < 10-2 ??

> 2 TeV ??

thallium

atom/moleculelevel

CP from particles to atoms (main connections)

nuclearlevel

NNNNSchiff

momentmercury

HiggsSUSY

Left/Right

StrongCP

field theoryCP model

GG

neutron

nucleonlevel

electron/quark level

de

dq

dcq

And now for the electron………..

The Thallium EDM experimentBerkeley B.C. Regan, E.D. Commins, C.J. Schmidt and D. DeMille

2 Tl atomic beams

= B

polarise

analyse

± dEE±B

The solution:add 2 more Tl beams going down

4

analyse

polarise

The solution:Add 4 Na beams for magnetometry

1st huge problem:motional interaction v E

2nd huge problem:stray static magnetic fields

A beautiful feature of the method

E

electric field

Interaction energy

-de E•

de

atom containing electron

amplification

-585 for Tl

(Sandars)

Effective field = 72 MV/cm 585

÷ 585electron edm result:

|de|< 1.6 10-27 e.cm

E = 123 kV/cm

B = 38 T

Tcoherence = 2.4 ms

Na co-magnetometer

Final Tl result: PRL 88, 071805 (2002)

|dTl|< 9.4 10-25 e.cm

Theoretical consequences of electron EDM

SUSY electron edm

e e

selectron

2mede ~ (loop) sin CP

No direct contamination from problem

- a pure new physics search

~ 5 1025 cm

This time natural SUSY is too big by 300

CP < 310-3 ?? > 4 TeV ??

potentially 1000 more sensitive

The Imperial experiment uses ytterbium fluoride molecules

E.A. Hinds, B.E. Sauer, J.J. Hudson, P Condylis, M.R. Tarbutt, R. Darnley

The future for electron EDM experiments

polar molecules

0

5

10

15

20

0 10 20 30

Applied field E (kV/cm)

Eff

ecti

ve f

ield

E

(G

V/c

m)

(in Tl experiment was 72 MV/cm)

13 GV/cm

First advantage of YbF: Huge effective field E

ParpiaQuineyKozlovTitov

2nd advantage of YbF:

No coupling v E to motional magnetic field

and internuclear axis is coupled to E

E

E = 0 no motional systematic error

electron spin is coupled to internuclear axis

Yb+

F-

1500K heater

Mocrucible

YbF beam

mirror

probe laser

PMT

Yb and AlF3 mixture

Forming and probing a YbF beam

The A-X 0-0 bandbandhead at 552.1 nm

174P(8)174Q(0)

174P(9)174Q(1)

4 5 6

174P(8)174Q(0)

174P(9)174Q(1)

4 5 6

1 3 5 7 9 11 15 17 19131 3 5 7 9 11 15 17 1913

GHz

GHz

GHz0.2 0.4 0.6 0.8

176P(9)

174Q(0)172P(8)

| -1 | +1

| 0

The lowest two levels of YbF in an electric field E

-deE

+deE

Goal: to measure the splitting 2deE

X2+ (N = 0,v = 0)

F=1

F=0

170 MHz

Interferometer to measure 2deE

Phase difference = 2 (BB+deE)T/

E B

PumpA-X Q(0) F=1

0

| -1 | +1

| 0

Split| -1

|+1

170 MHz pulseProbe

A-X Q(0) F=0

0 ?

Recombine170 MHz pulse

B and E1.5 m

The Sussex molecular beam

bea

m

oven

pump

split

recombine

detect

PMT

Part of the optical setup

135

136

137

-40 -20 0 20 40

The interferometer fringeIn

terf

eren

ce s

ign

al (

kp

ps)

Magnetic field B (nT)

Phase difference = 2(BB+deE)T/

Measuring the edm

Applied magnetic field

Det

ecto

r co

un

t ra

te

E

B0

-E

= 4deET/

-B0

4deET/

E = 8 kV/cm

B = 6 nT

Tcoherence ~ 1 ms

First YbF result: PRL 89, 023003 (2002)

background

fringe height

coherence time

de (24 hrs data)

150kHz

1.5 kHz

1.5 ms

< 3 10-26 e cm

Effective field = 13 GV/cm

Limited by counting statistics

Systematic erroreliminated….

PMT

dye laser550 nm

Supersonic YbF beam

10 bar Ar

solenoid valve target skimmer

YAG laser 1064 or 532 nm20 mJ in 10 ns

delay generator

scan

Labview control and DAQ

0 200 400 600

Laser offset frequency (MHz)

172 P(8)

176 P(9)

174 Q(0)

1500K thermal source

3105 useful molecules per second

0 200 400 600

Laser offset frequency (MHz)

174 Q(0)

172 P(8)

176 P(9)

10K supersonic source

3107 useful molecules per second

Possible experiment with trapped molecules

supersonic sourcedecelerator

pump split

trap ~ 1s

E

B

recombine probe

interferometer

Projections for the future

background

fringe height

coherence time

de in 1 day

2002result

150kHz

1.5 kHz

1.5 ms

3 10-26 e cm

cold YbFbeam

640kHz

160 kHz

1 ms

6 10-28 e cm

trappedmolecules

40kHz

10 kHz

1 s

3 10-30 e cm

long time = narrow fringes

d(muon) 7×10-19

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(neutron) 6×10-26

d(proton) 6×10-23YbF expt

coldmolecules

d(electron) 1.6×10-27

Conclusion

EDM measurements (especially cold molecules) have great potential to elucidate

• CP violation

• particle physics beyond the standard model

• matter/antimatter asymmetry of the universe

some of the most fundamental issues in physics