# Presentation: 448932

## Search for the electron electric dipole moment

-   electron EDM and new physics
-   how to detect an EDM
-   the previous and current generation of e-EDM searches
-   our approach:  electron EDM in PbO*

- D. DeMille
*Yale Physics Department University*

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

**Notes:**
Get more complete chart of EDM predictions from Yong
Get better group picture

## Virtual exotic particles can generate EDMs

- e

-  = E-field

***X***
- (new heavy particle)

*g’**e**i***

*g*

- Dimensionless
- coupling
- constant

- T-violating
- phase

- “natural” assumptions
*gg’*/*c*  **
- sin(**) ~ 1
*m**X** * ~ 100 GeV
- 
- typical e-*EDM d**e*
*~****B**(****/***)N(me/mX)2 sin
*d**e** * *100-1**** *
- current limit!
- (1 vs. 2 loops)

## Searching for new physics with the electron EDM 

## General method to detect an EDM

- Energy level picture:

- Figure of
- merit:

## Tl EDM schematic

- State of the art
- electron EDM search:the Berkeley
- Tl beam experiment

- Thermal beam of
-    atomic Tl (Z=81)
-  Efficient laser/rf spin
-   polarization & detection
-   count rate ~ 109/s
-   =120 kV/cm ( ~10-3)
-     int = 70MV/cm
-  L=100 cm   T3 ms
-  Counterpropagating
-    vertical beams to cancel
-    systematic effects from
-    **B**motional = ****** ** **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.C. Regan, E. Commins,
- C. Schmidt, D. DeMille
- Phys. Rev. Lett. **88**, 071805 (2002)
**|d****e****| < 1.6********10****-27**** e********cm (90% c.l.)**

## 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 solid | Huge S/N | 100? |
| S. Lamoreaux (LANL)
C.-Y. Liu (Indiana) | GGG solid | Huge S/N | 100?-100,000? |
| E. Hinds (Imperial) | YbF beam | Large Internal E | 2-3 |
| D. DeMille (Yale) | PbO* cell | Int.E+good S/N | 30!-1,000? |
| E. Cornell (JILA) | trapped HBr+ | Int. E + long T | ?? |
| N. Shafer-Ray (Okla.) | trapped PbF | Int. E + long T | ?? |

## Amplifying the electric field   with a polar molecule 

*********int***

**Pb****+**

**O****–**

- ext

**Explicit calculations indicate valence electron feels **
******int ****~ ********2****Z****3**** e/a****0****2**** ~ 2.1 - 4.0 ******** 10****10**** V/cm in PbO***
- semiempirical: M. Kozlov & D.D., PRL **89**, 133001 (2002);
*ab initio*: Petrov, Titov, Isaev, Mosyagin, D.D., PRA **72**, 022505 (2005).

**Complete electrical polarization **
**attainable with molecules subjects valence electrons to huge internal field **
- int**~10****11**** V/cm**
**with modest polarizing field**
******ext**** ~ 10-10,000 V/cm**

## YbF beam experiment (Hinds/Sauer, Imperial College)

- taking data now:
* ****d**e**(stat.)*~310-28 ecm
- anticipated

- Improved statistics
- w/new beam source vs. 2002

## Spin alignment & molecular polarization in PbO (no EDM)

## EDM measurement in PbO*

*“**Internal*
*co-magnetometer”:*
*most systematics *
*cancel in *
*comparison!*

- Novel state structure allows extra reversal of EDM signal

## Present Experimental Setup (top view) 

*Present Experimental Setup (top view)*

- Pulsed Laser Beam
- 5-40 mJ @ 100 Hz
-  ~ 1 GHz
****  **B**

- Larmor
- Precession
-  ~ 100 kHz

- PMT

**B**

- solid quartz
- light
- pipes

- Data
- Processing

- Vacuum chamber

**E**

- quartz oven structure

- PbO vapor cell

- Vapor cell technology allows high count rate
- (but reduced coherence time)

## Zeeman quantum beats in PbO

*Zeeman quantum beats in PbO*

- Excellent fit to Monte Carlo w/PbO motion, known lifetime
- Shot noise-limited S/N in frequency extraction
- (Laser-induced spin alignment only here)

## 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;
- improvements under way should reach target count rate: 1011/s.
- Shot-noise limited frequency measurement
- using quantum beats in fluorescence
- g-factors of -doublet states match precisely
- co-magnetometer will be very effective
- E-fields of required size applied in cell; no apparent problems

****** *****First useful EDM data ~late 2005;***
*********d******e***** ~ 3********10****-29**** *****e************cm within ~2 years...?***

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

## State preparation: microwave Raman excitation

*State preparation: microwave Raman excitation*

- laser-prepared
- superposition, as in proof-of-principle
- (not adequate for EDM)

- laser + wave
- preparation,
- as needed for EDM

## The PbO EDM group

_*Postdocs:*_
- David Kawall
**Val Prasad**
_*Grad students:*_
- Frederik Bay
**Sarah Bickman**
**Yong Jiang**
**Paul Hamilton**
_*Undergrads:*_
- Cliff Cheung
- Yulia Gurevich
_*Collaborators:*_
**Rich Paolino **
**(USCGA)**
**David Kawall **
**(UMass)**