# Presentation: 279046

##  Rare Kaon Decay Physics

** ****Rare Kaon Decay Physics**

**Lepton Photon Symposium**
**Augusto Ceccucci*/CERN**
**Fermilab, August 11, 2003**
***Member of the NA48 Collaboration **
** **

- LP2003, Augusto Ceccucci

- August 11, 2003

## Why study Rare Kaon Decays

**Search for explicit violation of Standard Model **
**Lepton Flavour Violation**
**Probe the flavour sector of  the Standard Model**
**FCNC**
**Test fundamental symmetries**
**CP,CPT**** **
**Study the strong interactions at low energy **
**Chiral Perturbation Theory, Form Factors**

**I will give a review of recent experimental results****  **
**In addition to *****K******L***** and *****K******+*****, also**** *****K******S***** rare decays *****(BR******≤******10******-8******)***** start to be studied**
**I will also briefly review the new initiatives that should lead  to significant advance in the field by the end of this decade**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Outline

**Tests of the Standard Model **
***K******L******→************0****** ee      *****KTeV-E799 II  (1999 data)**
***K******S******→************0 ******ee      *****NA48/1 CERN (2002 data)**
***K******+******→************+****** ***************BNL-E787  (1997 data, region II)**
**Other Tests of CP and CPT symmetry**
***K******L******→************ee******      *****KTeV-E799 II  (1999 data)***** *****      **
***K******S******→******3************0   ******       ******  *****NA48/1 (2000 data)**
***K******S******→************ e ************      *****KLOE Frascati (2001)**
**Chiral Perturbation Theory**
**Dalitz decays:***** ***
***K******L******→******ee************, K******L******→******eeee,****** ******K******L******→************ee****** *****KTeV-E799 II **
**Non-Leptonic decays**
***K******L******→************  ******        ***** KLOE (2001+2002 data)**
***K******S******→*****************NA48/1 (2000 data)**
***K******S******→************0*****************NA48/1  (2000 data)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Kaon Rare Decays and the SM

**Kaon Rare Decays and the SM**

**CP-Violation**

**(holy grail)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Theory of KL→0ee ()

**Complete re-analysis of the decay:**
**(Buchalla, D’Ambrosio, Isidori,  hep-ph/0308008)              BDI**
**Short Distance (Direct CP-Violation)**
**From  Standard Model fit: *****Im ************t  ******= (1.36 ± 0.12) 10******-4 ******  *****(CKM)**
***B(K******L******→************0******ee)******CPV-di******r******=(2.4 ******± 0.2) ×10******-12 ******× (Im ************t ******/10******-4******)******2****** = ***
***                                 ******(3.2 ± 0.4) × 10******-12******     ***
**Indirect CP-Violation**
***BR(K******L******→************0****** ee) ******CPV-ind****** ~1/330 BR(K******S ******→ ************0****** ee)***
**Direct and Indirect CP-Violating components interfere **
**CP-Conserving contribution **
**Need model ind. 3 par. fit (Gabbiani, Valencia, PRD 64 2001)**
***BR******CPC****** < 3 ******×******10******-12*****   **** (conservative, BDI) **
**They fix the 3 counterterms from *****K******L******→************0***********  and *****K******S******→*********** **

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV-E799-II (FNAL)

**Pure CsI  **
***m************~1 MeV***

**TRD**

***K******L****** flux ~ 7 ******× ******10******11***

- LP2003, Augusto Ceccucci

- August 11, 2003

## Experiment: KL→0ee ()

| Mode | Upper Limit
90% CL | Ref. |
| --- | --- | --- |
| KL→0 ee | < 5.1 × 10-10     | PRL86   (2001) |
| KL→ | < 3.8 × 10-10 | PRL84 (2000) |

**Experiment:***** K******L******→************0******ee (************)***

**Published data: E799-II (KTeV)   1997**

**Irreducible background: *****K******L******→ ******ee(************)************(Greenlee, 1990)***
**Same final state as the signal, only ******** mass resolution and kinematics**** are available to suppress these backgrounds**
**To keep it to the  ****~1  event level****  the acceptance is quite reduced **
**Possible future searches will be background dominated**

***K******L******→************0******ee *****KTeV 1997 data:**
**2 events consistent with the expected background of**
**1.06 ****± ****0.41****  events**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV: KL→ 0ee

***K******L******→******ee***********crossing**
** ****the signal box**
** ****(BR~6 10****-7**** !!)**

***K******L******→************0************0************0******D******,***
**           ********e********+********0****acc**

**DATA 1999**
**preliminary**

**M(ee********)**** computed using the ****neutral vertex****, assuming *****m(************=m(************0******)*****  **
**M(********)**** computed from ****charged vertex**

- LP2003, Augusto Ceccucci

- August 11, 2003

##  KTeV: 0ee vs ee  kinematics

**Minimum angle between **
**any e and ******

***K******L****** ******→******ee*********** “radiative”**
**distribution**

*********0****** ******→*********** “isotropic”**
**distribution**

**cos************0**

*********0****** ******→************ *****decay asymmetry**

**Expected background:**
**0.99 ± 0.33 events**** **

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV: KL→ 0ee

**One candidate in the signal box**
**Combining 1997 and 1999:**

**1999 data, preliminary**

***BR(K******L****** ******→ ************0 ******ee ) < 3.5 ******× ******10******-10 ******@90%CL***

***BR(K******L****** ******→ ************0 ******ee ) < 2.8 ******× ******10******-10 ******@90%CL***

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1 (CERN)

**NA48/1 (CERN)**

** ****NA48:     ***********’/************ *****, *****K******L***** rare decays**
** ****NA48/1:  *****K******S***** rare decays **
**Upgraded read out**
**High intensity**** short neutral**
** ****beam from the CERN-SPS**
**Run in ****2000**** (only ********s) and ****2002**

**Run 2002**

***NA48 (************’/************ ):***
***1997-1999***
***(2000)***
***2001***

**Liquid krypton **
**calorimeter**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

**e****+-****e****-+**** (Odd Sign) DATA**** **

**e****+-****e****-+**** DATA vs. MC**

**Blind Control**
**& Signal regions**

** *****m******ee****** > 0.165 GeV/c******2***** cut applied  to reject *****K******S****** ******→ ************0****** ************0******D****** *****with one missing***** *********

**m****ee**** (GeV/c****2****)**

**m****ee******** (GeV/c****2****)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

**e****+-****e****+-**** (Same Sign) DATA**

**e****+-****e****+-**** DATA vs. MC**

**Search region**

**m****ee******** (GeV/c****2****)**

**m****ee**** (GeV/c****2****)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

**Background from *****K******L,S******→******ee*********** :**
** ****measured using ****NA48***** K******L *****data from 2001**
***N(K******L******→ee************, ******2001) ************  10 ******× N(K******L,S****** ******→ee************, 2002)***

**m************GeV/c****2****)**

**m****ee********(GeV/c****2****)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

**DC proton beam**
**Read out window:  ~**** 2****00ns**
**Use time side band to measure background from time-overlapping fragments from differ decays**
**Major component:**
**e********+ ********0********0****(********0****)**
**Confirmed relaxing E/P cuts**

***m************ (GeV/c******2******)***

**Accidental backgrounds**

***m******ee************ (GeV/c******2******)***

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

| Source | Control Region | Signal region |
| --- | --- | --- |
| KS→0D0D | 0.03 | 0.007 |
| KL,S → ee | 0.11 | 0.075 |
| e+20(0) | 0.19 | 0.069 |
| Total | 0.33+0.18-0.11 | 0.15+0.05-0.04 |

**Many other sources investigated and found to be negligible ****(e,g neutral cascade decays)**
**Blind analysis:**** Control and signal region remained masked until the study of the background was finished**

**SUMMARY OF BACKGROUNDS:**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

**7 candidates**** in the**
** ****signal region **
**0 in control region**
**Background 0.15**
**The probability that all 7**
**events are background **
**is ~10****-10**

***m******ee************ (GeV/c******2******)***

***m************ (GeV/c******2******)***

**First observation of  *****K******S****** ******→************0****** ee***** **

- LP2003, Augusto Ceccucci

- August 11, 2003

## The 7 KS→0ee candidates

***M******ee************ (GeV/c******2******)***

***M************ (GeV/c******2******)***

***t/************S***

***M******ee****** (GeV/c******2******)***

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS →0 ee

***BR(K******S******→************0******ee, m******ee******>165 MeV/c******2******) = (3.0******+1.5******-1.2******(stat)****** ******± 0.2(syst))×10******-9***

**Assuming ****vector interaction and unity form factor:**
**In remarkable  agreement with L. Sehgal prediction:  ****~5.5 ×10****-9 ****NP B19 (1970)  **
**In the notation of D’Ambrosio et al. JHEP 08 (1998 004):**
***BR(K******S******→************0******ee) ******~******  5 |a******s******|******2***
***                             ******|a******s******|=1.08******+0.26******-0.21***

***BR(K******S******→************0******ee) = (5.8 ******+2.8******-2.3******(stat) ± 0.3(******syst******) ± 0.8(theor))×10******-9***

**Preliminary**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Sensitivity to Im t

**Sensitivity to *****Im ************t***

**IF the interference is constructive**** some sensitivity to *****Im ************t***** **** is retained**

***-a******s***

- LP2003, Augusto Ceccucci

- August 11, 2003

## KL→ee() Perspectives

**Detector ********   ****×2****   **
**Very ambitious, KTeV already state of the art**
***K******S******-K******L***** time dependent interference  ****×2**
**Position experiment between 9 and 16 *****K******S***** lifetimes **
**    ****(hep-ph/0107046)**
***K******S******-K******L***** time independent interference ****×3**** **
**Assume**** constructive interference (theoretically preferred)**
**Data Taking ****×5****  **
**Run in ****“factory mode”.**** After all E799-II  run only for a few months to collect ~7 × 10****11**** K****L**** decays**
**Beam intensity ****×4**** **
** ****Need ****~10****12 ****protons/sec****,**** slowly extracted, high energy, DC **
**Tot  ~ ×240 ****→****  ****sens~ ×15**** **
** ****close the gap between current upper limit and SM**
**Where? When?   **

***Admittedly aggressive Road Map***

**Expect KTeV to update *****K******L******→****************** ***********(1999 data)****   **
**NA48/1 analysis of *****K******S******→************************  *****is in progress**

- LP2003, Augusto Ceccucci

- August 11, 2003

## K+→+  (reminder)

**                      *****BR(K******+****** ******→ ************) = 7.1 ******± ******1.0 ******× 10******-10***
***                      *****(Kettell, Nguyen, Landsberg, hep-ph/0212321***** *****)**

***K******+******→************+****** ************ (*****reminder)**

**The hadronic matrix element can be extracted from **
** ****the ****well measured**  ***K******+******→****** ************0****** e ************ ***
**No long distance contributions**

**QCD NLO**
**Buchalla,**
**Buras 1999**

- LP2003, Augusto Ceccucci

- August 11, 2003

## K+→+ 

**    ****Region I**
***211 < P < 229 MeV/c***

**   ****Region II**
*** ******150 < P < 195 MeV/c***

******+**

**in the *****K******+***** CM**

- LP2003, Augusto Ceccucci

- August 11, 2003

## AGS-E787   K+→+ Region I

**Data 1995-1998**
**Pub.1997-2002**

**Stopped kaons (~6 ****×****10****12****)**
**Analysis of ****Region I:**** **
**          ****2 events**** **
** ****background:  0.15 ****± 0.05**** **

**AGS-E787   *****K******+******→************+****** ***********Region I**

***BR(K******+****** ******→ ************+ ************ , Region I)  = ***
***       ******1.57******+1.75******-0.83   ******×  ******10******-10***
***0.29 < | ************t****** |/10******-3****** < 1.2   68% CL***

**PRL 88 2002**

- LP2003, Augusto Ceccucci

- August 11, 2003

## E787- K+→+   Region II

**E787- *****K******+******→************+****** ************  *****Region II**

**1997 (preliminary)**
**No new events**
**Background 0.5 ****± 0.2**

**1996 data**

**1997 data**
**NEW RESULT!**

**1996**
**One event found **
**Background 0.7 ****± 0.2**

***BR(K******+****** ******→ ************+ ************ , Region II ) < 22 ******× ******10******-10 ******@90%CL***

**PLB 537 2002**

- LP2003, Augusto Ceccucci

- August 11, 2003

## K+→+    E949

***K******+******→************+****** ************   *****E949**

**Successor of E787**
**Many improvements**
**Better photon vetoes**
**Run 12 weeks in 2002:**
**Expect Region I result soon **
**Expect much better sensitivity than E787 in Region II**
**Expect from data 2002 an overall sensitivity comparable**
**    ****to E787 **
**Approved for 60 weeks **
**When will the next run take place? **

- LP2003, Augusto Ceccucci

- August 11, 2003

## Current Status

**Current Status**

**STILL A LARGE WINDOW OF OPPORTUNITY EXISTS**

**G. Isidori**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV: KL→ ee

**CPV asymmetry from the interference of IB and DE diagrams in *****K******→ ************+************-*********
**BR*****~3 ******×******10******-7 ***
**CPV asymmetry and form factors from full statistics**
**     ****(5056 events)**
**       ****A****L****= (13.3 ****±**** 1.4 ****± ****1.0)%**
**     ****(Theory: ~14%, Sehgal et al.)**
**Form Factors (preliminary):**
**a****1****/a****2**** = -0.75 ****±**** 0.03 ****± ****0.02 **
**g****M1**** = 1.10 ****± ****0.10 ****± ****0.06 **** **
**     **

**sin********cos ******

**  ****(1997+1999, preliminary):**

**KTeV  K****L**

**NA48 K****S**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS → 30 

**Near Beam**
**NA48/1 (2000) *****~6.5 10******6****** 3************0***
**Far Beam:**
**NA48 2000  > 10****7**** *****K******L******→******3************0***
**To normalise the acceptance**
**Analysis in bins of energy **

**CP-Violating**
**In SM***** ************000******~*********

***D(E)  *****is the***** K******0****** K******0****** *****dilution (from NA31)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS → 3

**From one parameter fit****:**
***BR(K******S******→3************0******) < 3.0 × 10******-7****** 90%CL***
***      ******BR******SM****** ~ 3 × 10******-9***

**From the 2 parameter fit,**
**using BS unitarity relation:**
**Im ********CPT**** = (-1.2 ****± 3.0) × 10****-5**
**Assuming CPT conservation in decay:**
***M(K******0******) –M(K******0******) = (- 1.7 ******± 4.2) × 10******-19****** GeV/c******2***

***Im ************000***

***Re ************000***

**CPT TEST:   *****K******L****** ~ ******(************+************CPT******)******K******1****** + K******2***
***                      ******K******S****** ~ K******1****** + ******(************-************CPT******)******K******2***

- LP2003, Augusto Ceccucci

- August 11, 2003

## KLOE (LNF)

***    ******DA************NE ************Factory:***
***e******+******e******- ******→ ************→ K******S******K******L   ******(K******+******K******-******)***

**Tagged *****K******S***** and *****K******L***

- LP2003, Augusto Ceccucci

- August 11, 2003

## KLOE: KS →e

**KLOE Preliminary (2001 data):**
***BR(************-******e******+************) = (3.44 ******± 0.09******stat****** ******± 0.06******syst******) × 10******-4***
***BR(************+******e******-************) = (3.31 ******± 0.08******stat****** ******± 0.05******syst******) × 10******-4***
***BR(************e ************) = (6.76 ******± 0.12******stat****** ******± 0.10******syst******) × 10******-4***

- LP2003, Augusto Ceccucci

- August 11, 2003

## KLOE: KS → e

**CPT test**
**First ever measurement:**
***A(K******S******) = (1.9******±1.7±0.6) ×10******-2***
**c.f.  *****K******L****** *****w.a. **
***A(K******L******) = (3.322 ******± 0.055) ×10******-3***
*********S=************Q *****test**
***Re (x******+******) = (2.2 ******± 5.3 ± 3.5) ×10******-3***
**c.f. CPLEAR**
***Re (x******+******) = (-1.8 ******± 4.1 ± 4.5) ×10******-3***

**Semileptonic asymmetries**
**        ****(preliminary)**

**PLB 535 (2002****)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Kaon Dalitz decays: Motivation

**Kaon Dalitz decays: Motivation**

**Allow to study the *****K*****-**************************)**** form factors **
**These form factors are related to the ****dispersive amplitude****  of *****K******L******→ ***********which is  not under good control **
**Short distance contributions to *****K******L******→ *****************are sensitive to  *****Re ************t ***
**            ****TWO MODELS:**
**BMS   (Bergstr****ö****m, Mass****ó,**** Singer, 1983)**
**Pseudoscalar/vector contributions:  ********K*******
**DIP  (D’Ambrosio, Isidori, Portoles, 1997)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV: KL→ ee

**In the 1997 data, KTeV has identified ****93,383 *****K******L******→******ee************ *****over a background of less than 0.1% **
**To determine the acceptance it is very Important to understand the ****tracking for close pairs **
**Uncertainty dominated by the error on the normalisation mode: **
**     *****K******L******→************0************0******D************0******D***** with ***********0******D****** ******→******ee*********

***BR(K******L******→******ee************)******×******10******6****** = 10.19 ± 0.04(stat) ± 0.07(syst) ± 0.29(norm******)***

***K************3***

**Employ TRD to reduce**
** ****background**

**Preliminary**

***Ke3***

**ee******

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV: KL→ ee

**KTeV: *****K******L******→ ******ee*********

*********K*******= -0.186 ******± 0.011 ± 0.009***

******K*****=0.20**

******K*****=-0.16**

******K*****=0.0**

******K*****=-0.36**

**Measured to ~7%**
**Precision!**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV: KL→ ee ee 

**KTeV: *****K******L******→ ******ee ee***** **

**Signal ~1100 events **
**Background:  5 events (mainly due to *****K******L******→******ee***********+ conv)**
**Normalisation: *****K******L****** ******→ ************0************0******D************0******D***
***                 ******BR(K******L****** ******→ ******ee ee) = (4.16 ******± ******0.13 ******± ******0.13 ******± ******0.17) ******×******10******-8***
***  ***
*********K******* = -0.03 ******± ******0.13 ******± 0.04***

**1997+1999 Data (preliminary)**

**Theory:**
**~3.5 10****-8**

- LP2003, Augusto Ceccucci

- August 11, 2003

##  DATA 1997+1999

** ****DATA 1997+1999**

**Signal: 132 events**
**Background ~0.8 event***** ***
***    ******(K******L ******→ ************+************- ***********)**
** **
** **

**PRL 90 (2003)**

**KTeV: *****K******L******→ ************ ee***

***BR(K******L ******→ ************+************-****** e******+******e******-******)=(2.69 ******± 0.24 ± 0.12)×10******-9***

***BR(K******L ******→ ************ ******-+************ -+******e******+-****** ******e******+-******) <  4.12 ******× 10******-11   ******90%CL***

**LFV**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KTeV KL→ ee

**Combining *****K******L****** ******→ ************, ******K******L****** ******→ ******4e,****** and  ******K******L******→************ee,***
**KTeV measures:**
*********(DIP) = -1.53 ± 0.10  ***

******K*****(********ee)= -0.19 ****± 0.11**

- LP2003, Augusto Ceccucci

- August 11, 2003

## K-(*)* Form Factor

***K-************(*)****************** Form Factor**

******K*******

**~2.6 ******

- LP2003, Augusto Ceccucci

- August 11, 2003

## KLOE:  KL→  

**KLOE:  *****K******L******→ *********** **

**Data 2001-2002**
**362 pb****-1****, 10****9**** ******
***K******L***** tagged by *****K******S******→************+************-***
*** *****1.6 ****×****10****8**** *****K******L***
***K******L****** ******→ ******3************0****** *****suppressed requiring 2 body kinematics**
**   ****27375 *****K******L******→ ************ ***
**   ****PL B556 2003**

-  *********(K******L************ ************ ************ ) / ************(K******L****************************** ****************** ******)******  ******=****** (2.79 ± 0.02******stat****** ± 0.02******syst******) ************ 10******-3***
**In good agreement with the NA48 result (PL B551 2003):**
*********(K******L************ ************ ************ ) / ************(K******L****************************** ****************** ******)******  ******=****** (2.81 ± 0.01******stat****** ± 0.02******syst******) ************ 10******-3***

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS  γ

**NA48/1: *****K******S****** ************ ******γ*********

***BR ( K******S****** ************ ******γγ )  = (2.78 ± 0.06******stat ******± 0.03******syst****** ± 0.02******ext****** )×10******-6***

**PLB 551 (2003) **

- LP2003, Augusto Ceccucci

- August 11, 2003

## KS  γγ  measurements

***K******S****** ************ ******γγ*****  measurements**

**The NA48/1 result has  an accuracy better than 3% **
**It differs  by****   ****30%  from   *****O(p******4******)***** prediction   of   CHPT**
**Used to fix one *****O(p******6******)***** counterterm:**
***8m******K******2******/F************2****** a******1****** = 1 ******± 0.3***
** ****BDI (hep-ph/0308008)**

**NA48/1**

**PL B551 2003**

***O(p******4******)***

***2.78 ******± 0.07***

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1:  KS    

**NA48/1:  *****K******S****** ************************ ***********  **

- PRELIMINARY: first observation

***BR(K******S****** ************ ****************** ******γγ, ******z******q************0.2****** ) = (4.9 ± 1.6******stat ******± 0.8******syst****** )×10******-8***

** ****CHPT predicts (Ecker, Pich and   PLB 189 1987): *****BR(K******S****** ************************ ************ ) ******zq > 0.2 ******=3.8 ************ 10 ******–8***

***Z******q******=q******2******/M******K******2***

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/2 and OKA: K+/K-

***NA48/2 is taking data***

**Search for direct CP violation**
**  ****in Dalitz plot slope asymmetry**
**  ****in *****K******± ************ *********** decay**
*** ******K******e4 *****decays**
** ****Rare *****K******±*****  **** decays**

**    ****Simultaneous**
**  *****K******+***** and *****K******-***** beams**

**NA48/2**
**Very Preliminary**

***K******± ******→ ************± ******ee***

**Similar sensitivities expected from OKA @Protvino (2004?)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## CKM@FNAL-MI  (2009?)

**CKM@FNAL-MI  (2009?)**

**Proposal to measure **** ~100 *****K*****+****→********+**** ******** in flight**** **
**Make redundant measurements: spectrometer and RICH**
**Built full size prototype of SCRF for *****22***** *****GeV/c *****separated beam**
**Measured inefficiency of photon vetoes @1GeV to be ****5****×****10****-6**** **
**×6 better than needed**
**Demonstrated operation in vacuum of straw tubes**
**Awaiting approval ratification by P5**

- LP2003, Augusto Ceccucci

- August 11, 2003

## E391a@PS-KEK

**E391a@PS-KEK**

**First dedicated experiment to search for *****K******L******→****** *********************
**SES~ 3 10****-10**
**Based on pencil kaon beam and photon vetoes**
**Scheduled for ~100 days KEK PS beam in 2004 **
**This is a Stage I project for further study at J-PARC**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KOPIO@BNL (2009?)

**KOPIO@BNL (2009?)**

**Aim to collect 60  *****K******L******→****** *********************
**     ****events with S/B~2        *****(Im ************t****** *****to***** 15%)***
**Measure as much as possible**
**Energy, Position and Angle for each photon**
**Work in the Kaon Center of Mass **
**Micro-bunched AGS beam**
**Use TOF to measure  *****K******L***** momentum**
**Start construction in 2005?**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Conclusions

**High Energy  **
**Frontier **

**Rare Processes**

**Conclusions**

**The field of kaon rare decays is ****quite active**** **
**New experimental initiatives are ****planned**
**Significant tests of the SM are to be expected **
** ****by the end of the decade**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Spare Material 

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48: KL,S→ee

- LP2003, Augusto Ceccucci

- August 11, 2003

## CP-Violation in SM

**CP-Violation in SM**

***    ******J******CP******=2************(Triangle Area)  *****Is the unique measure of CP-Violation in SM**

***N******g******=2    N******phase******=0   ********* No CP-Violation**
***N******g******=3     N******phase******=1  ********* CP-Violation Possible**

**A phase  in the  quark-quark current leads to **
**CP-Violation ****(Kobayashi, Maskawa, 1973)**

**6 unitarity relations**
**( triangles in the complex plane)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## Consistency of CKM picture

**Consistency of CKM picture**

**Paradigm shift:**
**Old question:****  (before the ***********’/***********  and *****B******→******J/************ K******s***** asymmetry measurements): **
**Is CKM ****the**** source of CP-violation?**
**New question****:**
**Is  CKM ****the only****  source of CP-violation?**
**Decisive tests must have small theoretical errors**
**The opportunity is to compare information from *****K***** rare decays and *****B***** mesons **

- LP2003, Augusto Ceccucci

- August 11, 2003

## Kaon Dalitz decays: Motivation

**Kaon Dalitz decays: Motivation**

**Short distance contributions to *****K******L****** ******→*********** sensitive to *****Re ************t***** **

**Long distance contributions:**

**Absorptive  part  *****(Im A************)***** is dominant  (2 real photons) **
**Dispersive part**** *****(Re A************)***** depends on the**
** *****K-**************************************)***** form factors**** that can be studied with **
** ****the ****Dalitz decays****:**
**Is much less under control**
**Can interfere with the SD piece**
** **

**Buchalla & Buras 1994 **

- LP2003, Augusto Ceccucci

- August 11, 2003

## Form Factors K**

**BMS   (Bergstr****ö****m, Mass****ó,**** Singer, 1983)**

**  ****DIP  (D’Ambrosio, Isidori, Portoles, 1997)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## KL → 0  (reminder)

***K******L****** ******→****** ************0****** *********** (reminder)**

**Theoretical error ~2%:**
**Purely CP-Violating (Littenberg, 1989)**** **
**Totally dominated from t-quark**
**Computed to NLO in QCD (e.g. Buchalla Buras, 1999)**
**No long distance contribution SM~3 ****× ****10****-11**

** ****Experimentally:  ****2/3 invisible final state !!**
** ****Best limit from KTeV using  *****************→ee*********** decay**

***BR(K******0****** ******→ ************0************) < 5.9 ******× 10******-7   ******90% CL***

**Still far from the model independent limit:***** ***
***BR(K******0****** ******→ ************0************) < 4.4 ******× ******BR(K******+****** ******→ ************+************) ~7 ******× ******10******-9****** ****** ***
**Grossman & Nir, PL B407 (1997)**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48: KL→

**Data 2000**
**sub-sample of  *****K******L****** *****data**
**Background:**
**Hadronic origin**
** ****0.6 ****± 0.3 %**
**Main systematics:**
**calorimeter response for the acceptance calculation**

-  *********(K******L************ ************ ************ ) / ************(K******L****************************** ****************** ******)******  ******=****** (2.81 ± 0.01******stat****** ± 0.02******syst******) ************ 10******-3***

**4 times better precision than  PDG:  (2.77 ****± 0.08) ******** 10****-3  ****  **

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1 KS  γγ

-   **Older NA48 measurement  of  ****K****S**** ******** ****γγ**** **
**     ****branching ratio based on 2 days of   **
**     ****test-run  in 1999 with high intensity K****S**** :**
**    ****(2.6 ****± 0.4) ******** 10 ****–6    ****   ****    PLB 493 (2000)  **

***NA48/1 K******S****** ************ ******γγ***

-   **Decays into  neutral final states :  *****O(p******2******) = 0 ***

-   **O(p****4****) unambiguosly predicted by **
**    ****ChPT loop diagram  to better **
**     ****than 5%  without counter terms: **
**     ****Theory: *****BR(K******S******→****** ************, O(p******4******))=2.1 10******-6***

**No indication of O(p****6****) contributions**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS → 0 ee 

**To reject the *****K******S****** ******→ ************0****** ************0******D******  *****decays that may mimic *****K******S****** ******→************0****** ee***** if a ******** is lost, a cut *****m******ee******>0.165***** *****GeV/c******2***** is applied**

***K******S****** ******→************0****** ee***

***K******S****** ******→ ************0****** ************0******D******→************ee(************)***

**MC**

**MC**

- LP2003, Augusto Ceccucci

- August 11, 2003

## NA48/1: KS  

**NA48/1*****: K******S****** ************************ *********

-    **Previous limit (NA48):**
**      ****BR(K****S**** **************** ********, z****q**** > 0.2 ) < 3.3********10 ****–7****  at 90% CL **

-    **ChPT predicts (Ecker,  Pich, De Rafael -  PLB 189 (1987)): **
-                                                                       **BR(K****S**** **************** ******** ) ****zq > 0.2 ****=3.8********10 ****–8**

- LP2003, Augusto Ceccucci

- August 11, 2003

## OKA @ Protvino - K 

**New RF-separated beam at U-70 PS in construction****15 GeV/c kaons, alternating *****K******+***** or *****K******-*****Magnetic detector evolved from ISTRA+, GAMS****In preparation, expected 2004****Measurement of 3******** Dalitz plot asymmetries @ 1 ********10****-4****T-odd correlations, search for New Physics in K****l2**** decays**

- LP2003, Augusto Ceccucci

- August 11, 2003

## CKM@FNAL-MI (2009)

**SCRF 13 cell cavity **
**Built full size prototype**
**Photon vetoes**
**Measured inefficiency for 1GeV ********:  ****5****×****10****-6**** **
**×6 better than needed**
**Straw tubes**
**Demonstrated operation in vacuum **
**Same preformance as in air**
**Simulation of “triggerless DAQ”**
**Awaiting approval ratification by P5**

**From CKM proposal**

- LP2003, Augusto Ceccucci

- August 11, 2003

## OKA @ Protvino - K 

**New RF-separated beam at U-70 PS in construction****15 GeV/c kaons, alternating *****K******+***** or *****K******-*****Magnetic detector evolved from ISTRA+, GAMS****In preparation, expected 2004****Measurement of 3******** Dalitz plot asymmetries @ 1 ********10****-4****T-odd correlations, search for New Physics in K****l2**** decays**

- LP2003, Augusto Ceccucci

- August 11, 2003