Tabletop probes for TeV physics:the search for electric dipole moments

  EDMs and new physics

  how to detect an EDM

  electron EDM in atoms & molecules

  the state of the art electron EDM search

  the next generation

  our approach: PbO*

D. DeMilleYale University

Physics Department

Funding: NSF, Packard, CRDF, NIST, Sloan, Research Corp.

Review:

Fortson, Sandars, & Barr

Physics Today June 2003

An EDM Violates P and T

CPT theorem T-violation = CP-violation

B-B dipoleMagneticH E- E-

ddH dipoleElectric

T

Sd

P

PurcellRamseyLandau

T-violation: a window to new physics

• CP-violation observed in K- and B-mesons T is NOT conserved in nature

• K-, B-meson observations consistent with SM/CKM description including O(1) phase

but also consistent w/models containing new sources of T-violation

• CP-violation in SM is minimal: SM extensions typically include NEW sources of T-

violation

• Observed baryon asymmetry in universe REQUIRES new sources of T-violation

Virtual exotic particles can generate EDMs

e

= E-field

X(new heavy particle)

f’eif

Dimensionless coupling constant

T-violating phase

“natural” assumptions

ff’/ħc sin() ~ 1

mX ~ 100 GeV

typical e-EDM~

de~B

(/)N (me/mX)2 sin()

de 100-1× current limit!(1 vs. 2 loops)

Electron EDM in various SM extensions

not renormalizable loop diagrams

2

5 Fde

d L

ee

Experimental limit:|de| < 1.610-27 ecm

Physics model |de|

Standard Model ~10-41 e·cm

Left-right symmetric

10-26-10-28 e·cm

Lepton flavor-changing

10-26-10-29 e·cm

Multi-Higgs 10-27-10-28 e·cm

Technicolor 10-27-10-29 e·cm

Supersymmetry < 10-25 e·cm

B. Regan, E. Commins, C. Schmidt,

D. DeMille, PRL 88, 071805 (2002)

Models assumenew physics at ~100 GeV& CP-violating phases ~1

Searching for SUSY w/ the electron EDM Implications of current and ongoing electron

EDM searches

HsF

A-CP

A-Un

Align

de (e cm)

10-26 10-28 10-30 10-32 10-34

NAIVE SUSY

SO(10) GUT

AC: Accidental CancellationsHsF: Heavy sFermionsA-CP: Approx. CPA-Un: Approx UniversalityAlign: AlignmentE-Un: Exact Universality

AC E-Un

n (ILL,PNPI) Hg (Seattle)

Tl (Berkeley)

EDM <710-26 <210-28 <110-24 dn 710-26 210-25 de 1510-27 1.610-27 QCD 410-10 210-10 q/l, SUSY 110-2 210-3 110-2 xq/l, LR

110-2 110-3 310-2

Higgs 3/tan 0.4/tan 0.3/tan

Current status of ALL EDM searchesBest limits on “natural” parameters from 3 complementary experiments:

Barr Lamoreaux Romalis DeMille

General method to detect an EDM

Energy level picture:

Figure of merit for statistical sensitivity:

NTENST

dE

resolution

shift 1//1

E+2dE

+2dE

B

E-2dE

-2dE

B

B B

E-field on an electron? (part I)

electric forces can be cancelled by magnetic forces:

<Ftot> = <Fel + Fmag> = 0, <Eeff> = -<Fmag>/e

crBmag

vEBF ~

(spin-orbit energy)

Strongly peaked near nucleus: v, E, large

and each grows w/Z Fmag Z3

magnetic forces arise from

spin-orbit interaction:

E-field on an electron? (part II)

simple estimate: |<Eeff>| Z32 (e/a02) P

~ P 1011 V/cm @ Z~80!

polarization P required to unbalance vector average of Fmag (external E

necessary!)<Eint> = 0 Eext<Eint> 0!

Sandars

Na detectors

Na detectors

Na reservoir (~350 C)

Na reservoir (~350 C)

590 nm laser beams

590 nm laser beams

RF 1

RF 2

State of the artelectron EDM search:

the Berkeley Tl beam experiment

• Thermal beam of atomic Tl (Z=81)

• Efficient laser/rf spin polarization & detection count rate ~ 109/s

• E =120 kV/cm (P ~10-3) Eint = 70MV/cm

• L=100 cm T3 ms

• Counterpropagating vertical beams to cancel systematic effects from Bmotional = E v/c

(but: complex procedure to null residuals)

• B-field noise rejection with side-by-side regions

• Na atoms (low Z, small enhancement)

as “co-magnetometer” to check systematics

(but: little utility in practice)

New electron EDM limit:

B. Regan, E. Commins, C. Schmidt, D. DeMillePhys. Rev. Lett. 88,

071805 (2002)|de| < 1.610-27 ecm

(90% c.l.)

Tl detectors

Light pipeTl detectors

photodiodes

Beam stop

Beam stop

Collimating slits

Collimating slits

E-field plates(120 kV/cm)

State Selector/Analyzer

Analyzer/State Selector

Tl reservoir (~700 C)

Tl reservoir (~700 C)

378 nm laser beams

378 nm laser beams

Up beam oven

Down beam oven

B atomic beams

Systematic effects: B correlated with E (part 1)

Example 1:leakage current I E BE E

electron

magnetic

moment

e 1016 de!

Very small

values

BE ~ 10-11 G significant

|Btot| = |B0 + BE|

changes on reversal of E

B0 BE

E

Systematic effects: B correlated with E (part 2)

y = v(x)E(z)

E(z)

misaligned B0

Btotal (+E)Btotal (-E)

Bmot (+E)Bmot (-E)

If B0 and E are not exactly parallel, |Btot| = |B0 + Bmot| changes on reversal

of E:

Solution: avg. over counterpropagating beams residuals are product of two imperfections (i.e., one v-

mismatch one wrong B-component)

Example 2: motional magnetic field Bmot = Ev/c

A new generation of electron EDM searches

Group System Advantages Projected gain

D. Weiss (Penn St.) Trapped Cs Long coherence ~100

D. Heinzen (Texas) Trapped Cs Long coherence ~100

H. Gould (LBL) Cs fountain Long coherence ?

L. Hunter (Amherst) GdIG Huge S/N 100?

S. Lamoreaux (LANL) GGG Huge S/N 100?-100,000?

E. Hinds (Imperial) YbF beam Internal E-field 2-?

D. DeMille (Yale) PbO* cell Internal E-field 100-10,000?

E. Cornell (JILA) trapped HBr+ Int. E + long T ??

N. Shafer-Ray (Okla.) trapped PbF Int. E + long T ??

YAG lattice

Linear PhotodiodeArray

10 cm

Electron EDM with cold trapped atoms

and guide beams

Atoms loaded from below

David Weiss et al. (& similar D. Heinzen et al. )

5 VE ~1.5×10

cm

Coherence time: T ~2 - 5 s

Atom number:

8CsN ~2x10 9

RbN ~8x10

trappedatoms

Cs (Z=55) EDM plus Rb(Z=37) comagnetometer

x100 for Cs Eint

de ~ 10-29 ecm

for both Cs and Rb

in ~1 day

Solid state electron EDM searches

1: B from E

E

Sample magnetization

M deE/T

magnetometer coil

Expt: Lamoreaux (LANL)

2: E from B

BV

Sample voltageV de

Expt: Hunter (Amherst)

ShapiroLamoreaux

DeMille

A new direction in EDM searches:using molecules to search for de

Extremely large effective E-field with lab-size external field:

P ~ 1 Eeff ~ 1011 V/cm

(For atoms, P ~ 10-3 @ Eext ~ 100kV/cm) 

Smaller signals due to thermal distribution over rotational levels (~10-4)

  Molecules with unpaired electron spins are

thermodynamically disfavored high temperature chemistry, even smaller signals

Addressing some problems with molecules:the metastable a(1)[3+] state of PbO

   PbO is thermodynamically stable (routinely purchased and vaporized)

a(1) populated via laser excitation (replaces chemistry) 

 a(1) has very small -doublet splitting complete polarization with very small fields (>10 V/cm),

equivalent to E 107 V/cm on an atom! 

can work in vapor cell(MUCH larger density and volume than beam)

PbO Cell: Tl Beam:N = nV ~ 1016 N = nV ~ 108

Amplifying the electric field E with a polar molecule

Eint

Pb+

O–

Eext Complete molecular

polarization of PbO*

achieved at Eext ~ 10

V/cm

Explicit calculations indicate valence electron feels

Eint ~ 2Z3 e/a02 ~ 1.8 - 4.0 1010 V/cm

semiempirical: M. Kozlov & D.DeMille, PRL 89, 133001 (2002); ab initio: T. Isaev et al., PRA 69, 030501 (2004); A. Titov, priv. comm.

Populating the a(1) [3+] state of PbO

1+1-

~11 MHz

X(0) [1+]

0+

1-

2+

~10 GHz

•••

a(1) [3+]

2+

2-

•••

Laser pulse

~ 571 nm bandwidth ~ 1 GHz ~ Doppler

An aside: what’s an -doublet?

-90 0 90 180 270angle to molecular axis

En

erg

y

Symmetric-antisymmmetric states split by tunneling

LSJe

...

En

,

Non-rotating moleculehas internal

tensor Stark shift

22 eSt JnE

Spin alignment & molecular polarization in PbO (no EDM)

m = 0 E

+

-n

+

-

n

+

-n

+

-

n

m = -1 S m = +1 S

X, J=0+

|| z

S

Brf z

BJ=1-

J=1+

+

- +

-+

+

- +

-

-a(1) [3+]

EDM measurement in PbO*:

New mechanisms for suppressing systematics!

Most systematics cancel in comparison!

+

-n

+

-

n

+

-n

+

-

n

B EEEEE

Farmer :: Pig :: Truffle

The cruel reality of precision measurements (c.f. S. Freedman)

Theorist :: Experimentalist :: Fact

PbO vapor cell and oven

Sapphire windows

bonded to ceramic frame with

gold foil “glue”

quartz oven body800 C capability

wide optical accessw/non-inductive heater

for fast turn-off

Gold foil electrodes and “feedthroughs”

Present Experimental Setup

Pulsed Laser Beam5-40 mJ @ 100 Hz ~ 1 GHz B

Larmor Precession ~ 100 kHz

Photo-multiplier tube

B

Si g

nal

Frequency

solid quartz lightpipes

DataProcessin

g

Vacuum chamber

E

The PbO EDM lab

.001 km

Zeeman quantum beats in PbO

Excellent fit to Monte Carlo w/PbO motion, known lifetime

Shot-noise limited S/N in frequency extraction

RF electric resonance in PbO Zeeman splitting ~ 450 kHz

Zeeman splitting slightly different in lower level

~11 MHz RF E-fielddrives transitions

~1.6 ppt shift in Zeeman beat freq.

g/g =1.6(4) 10-3

-doublet will be near-ideal

co-magnetometer

Also:= 11.214(5) MHz;

observed low-field DC Stark shift

Current status: a proof of principle

•PbO vapor cell technology in place

•Collisional cross-sections as expected anticipated density OK

•Signal sizes large, consistent with expectation; straightforward improvements will reach target count rate: 1011/s.

•Shot-noise limited frequency measurementusing quantum beats in fluorescence

•g-factors of -doublet states match preciselyco-magnetometer will be very effective

•E-fields of required size applied in cell; no apparent problems

First EDM data in fall 2004;de ~ 10-29 ecm within ~2 years

[D. Kawall et al., PRL 92, 133007 (2004)]

The PbO EDM group

Postdocs:David KawallVal Prasad

Grad students:Frederik Bay

Sarah BickmanYong Jiang

Jonathan Jerke

Undergrads:Cliff Cheung

Yulia Gurevich

Visitors:Rich Paolino (USCGA)