# Presentation: 674212

## KOPIO Capabilities:Other Physics Goals

- 24 June 2005
- Michael Sivertz
- BNL

**Measuring Rare Kaon Decays with KOPIO**

## KOPIO Capabilities

- Hermetic Veto Coverage for both charged 	particles and photons
- High precision Shashlyk Calorimetry for
- 		EM Showers in Calorimeter
- Precision Charged Particle Tracking in 	Preradiator
- Time-of-Flight measurement for Kaon 	Momentum
- High Intensity Kaon Beam giving sensitivity 	corresponding to 10**14** K**L** decays

## Decay modes with a 

- Analysis of the decay mode K**L**  **o** S with S unobserved can simultaneously be used in a search for decays to a sGoldstino (superpartners of Goldstone fermions) that could be a Scalar weakly interacting boson.
- Current limits from E-949:
- 	B(K**+**  **+** S) < 5.9 x 10**-11**
- Look for the Pseudoscalar sGoldstino in
-    K**L**  **o** **o** P
- Limit from ISTRA for M**p**<200 MeV/c**2**
- B(K**-**  **-**** ** P) < 9 x 10**-6**

- 0           100           200
-       E1 – E2  (MeV)

- 200
- 100
- 0

- P*(o)
- MeV/c

## KL o  and KL o o 

- KL **o** ****gives information on the CP allowed contribution to KL** ********o** e+e-.
- KTEV gives a result of ~10-7 for the Br.
- If KOPIO can deal with the ** ********o**** ********o **background, then we should be able to add to this result.
- B(KL o o ****5.6 x 10-6 from NA31.
- Conflicting predictions:
- Heiliger and Sehgal predict 10-8
- Ecker, Neufeld and Pich predict 7 x 10-11
- KOPIO should be able to improve on the existing limit.

## Radiative Decays:KL , KL KL KL 

| Decay | Expt | Kaon decays | Events | Bkgd | PDG Value |
| --- | --- | --- | --- | --- | --- |
|  | NA31 | 4.7 x 108 | 110000 | 700 | B=(5.90±0.07) x 10-4 |
| e+e- | NA48
KTEV | 4.1 x 109
6.4 x 1011 | 6864
93400 | 10
476 | B=(1.00±0.05) x 10-5
K*= -0.186±0.011±0.009 |
| +- | KTEV | 6.4 x 1011 | 9327
 | 222 | B=(3.62±0.04±0.08) x 10-7
K*= -0.160+0.026-0.028 |
| e+e-e+e- | KTEV | 6.4 x 1011
 | 1056 | 7.9 | B=(4.16±0.13±0.13) x 10-8
K*= -0.03±0.13±0.04 |
| e+e-+- | KTEV | 6.4 x 1011 | 132 | 0.8 | B=(2.69±0.24±0.12) x 10-9 |
| +- +- | - | - | - | - | Not possible at KOPIO |
|  | NA31 | 4.7 x 108 | - | - | B < 2.4 x 10-7 |

- At what rate we can accept radiative decays
- without compromising rare decay modes?

## NA48 measured (N. Cabibbo, 2005) rescattering of
oo in 2 x 108 K++oo decays.  
Observed a cusp in the
 m2 plot.  From this
 they were able to 
 obtain  S-wave 
 scattering lengths.
KOPIO hopes to be
 able to add to this.
(a0-a2)m=0.281±0.007(stat)±0.014(syst)±0.014(theo)

- oo in 2 x 108 K++oo decays.
- Observed a cusp in the
-  m2 plot.  From this
-  they were able to
-  obtain  S-wave
-  scattering lengths.
- KOPIO hopes to be
-  able to add to this.
- (*a**0**-a**2**)m********=0.281**±0.007(stat)±0.014(syst)±0.014(theo)*

**********–**************scattering length from** **KL ************************decays****

- m**************** in K++oo

## KL beta decay

- Current predictions for  KL  K e ****are ~10-8.
- Look for K+******+********o** with a ******o** vertex that is displaced, with back-to-back pions, and a very low energy electron.
- Background from K**L** ******+********o** e **** has energetic electrons and narrow pion opening angle.
- Beta decay rate is proportional to ****m5 where ****m is the K**L**-K+ mass difference.
- Measurement of the beta decay rate could yield a K**L**-K+ mass difference to ~10keV

## KOPIO anticipates accumulating data on ~1014  kaon decays.  This will include a large sample of 2o and 3o decays.
Tagging these o decays will allow improved measurements of e.g.
o  e+ e-     (6.2 ± 0.5) x 10-8 
o        <1.7 x 10-6
KL lifetime is measured to ~1%.  The large sample of K decays may allow for a higher precision result from KOPIO.

- Tagging these ******o**** **decays will allow improved measurements of e.g.
**********o ** e**+** e**-**     (6.2 ± 0.5) x 10-8
******o **       <1.7 x 10-6
- KL lifetime is measured to ~1%.  The large sample of K decays may allow for a higher precision result from KOPIO.

- Tagged ****o decays and KL Lifetime

## Summary

- Lots of possibilities for new physics and improved precision measurement with the anticipated KOPIO data set.
- Looking for new collaborators to help us with the physics program and build the detector to accomplish these goals.
- New ideas welcome!