# Presentation: 206892

## Weak Interactions in the Nucleus III

- Summer School, Tennessee
-  June 2003

## P, C and T

**Unlike the continuous transformations, these are not associated **
**with additive quantum numbers, but multiplicative ones, if any.**

**exmpl:**

**In L=0 state**

## P, C and T

**Charge conjugation **
*the Dirac equation with E&M *
*interaction exhibits a symmetry: *

**We now know that all particles have associated antiparticles that have **
**opposite charge and identical other quantum numbers.**

**How do we obtain the operator *****C***
**such that:                                       **

**We need:                                       **

## P, C and T

**Charge conjugation **
*example: *

**E<0**
**Spin-down *****e******- ***

**E>0**
**Spin-up *****e******+ ***

## P, C and T

**Charge conjugation symmetry **
*clearly broken by Weak Interaction*

## P, C and T

**Time Reversal **

**Example of construction:*** *

**but how about *****S*****?**

**Need to include in addition**

**Time Reversal **
*Wigner showed that it*
*needs to be anti-unitary *

## Slide 7

## Slide 8

## CP-violation and matter-anti-matter asymmetry

**CP-violation and supersymmetry**

**CP-violation so far observed in K decays could be explained by**
**a (non-trivial) phase in the CKM matrix**

**But this is not enough to explain the matter-anti-matter **
**asymmetry presently observed in Universe.**

**Supersymmetry predicts CP violation observables larger than**
**predicted by SM. **
**For example, in the scenario that supersymmetry**
**will appear at the next run in the LHC:**
**unless large suppressions are at**
**work, the EDM should be on the order of **
**100 below the present limit.**

## Slide 10

## Expensive to pick up a phase in the Standard Model:

**According to the Standard Model it is very hard **
**to observe TRIV in nuclear Weak decays**

## Cheaper to pick up a phase in extensions of the Standard Model:

**Example: Lepto-Quarks**

## Slide 13

## Slide 14

## Detecting D: problems and solutions

- 1) neutrino too hard to detect

- Problem

- Solution

- 1) Detect proton instead

- 2) proton energy less than 1 keV:
- too hard to detect

- 3) potential systematic effects
- may require information
- on position of electron

- 2) accelerate protons to  30 keV.

- 3) use plastic scintillator and
- detect amplitude and time on
- both ends.

## First phase of emiT: PRC 62, 055551 (2000). 

- First phase of emiT: PRC 62, 055551 (2000).

*time between p and e*

*p energy*

## emiT published first results in 2000 that yielded 

**emiT published first results in 2000 that yielded **
**D=0.6********1.2(stat)********0.5(syst) x10****-3**
**and is now running an upgraded version**
**that should yield D<310****-4**

*time between p and e*

*p energy*

- Second phase of emiT: presently running.

## Electric Dipole Moment

**Existence of EDM violates Time-Reversal symmetry:**

**But for a **
**non-degenerate **
**system:**

**EDM operator does **
**not flip sign under T:**

**Electrons, nuclei and atoms are non-degenerate systems, consequently a non-zero *****d***** implies violation of T.**

## Electric Dipole Moment

**Existence of EDM violates Time-Reversal and P symmetries:**

**But for a **
**non-degenerate **
**system:**

**EDM operator does **
**flip sign under P:**

**Electrons, nuclei and atoms are non-degenerate systems, consequently a non-zero *****d***** implies violation of P.**

## Electric Dipole Moment

**The operator for EDM:**

**does not flip sign under T.**

** ****But the eigenvalue does: **

## Naively: EDMs on composite neutral systems (e.g. atoms) cancel out.

- 1) Schiff showed that this is** incorrect **because of the finite size of the atom
- nuclear charge density ≠ dipole-moment density.
- Suppression factor = (Z nuclear size/atom size)2

- 2) Sandars (relativistic effects; contribution from electrons):
- EDM(atom) α Z32 EDM(e)
- enhancement  103 for Tl

- 3) Sandars : In polar molecules field at atom can be much larger than
- external field.
- Enhancements  103

## Neutron EDM; Ramsey,

- Dress et al. Phys. Rep. 43, 410 (1978).

## Neutron EDM; Ramsey,

- Dress et al. Phys. Rep. 43, 410 (1978).

- Simplified version

**incoming **
**neutrons**

**polarizer**

******/2 pulse**

******field**

**analyzer**

******/2 pulse**

## Neutron EDM; Ramsey,

- Dress et al. Phys. Rep. 43, 410 (1978).

## From Rosenberry and Chupp, 

*From Rosenberry and Chupp, *
*PRL ****86****, 22 (2001).*
*d*(129Xe) = 0.7*±*3.3(stat)*±*0.1(syst)
- x 10-27*e *cm.

## Present limits on EDM’s  

- d(e) <1.6 10-27 e cm,  PRL **88**, 071805

- d(199Hg)<2.1 10-28 e cm PRL **86**, 2506

- Present limits on EDM’s

## Large potential enhancement in nuclei

- Spevak, Auerbach, Flambaum, PRC 56, 1357 (1997).

- Engel, Friar and Hayes, PRC 61, 035502 (2000).

- Haxton, Henley, PRL 51, 1937 (1983).

## Slide 28

## The End