ICHEP04 Beijing 16-22 aug 2004 Rare Kaon Decays and CP, TCP Violation Vincenzo Patera* LNF/INFN...

ICHEP04 Beijing 16-22 aug 2004

Rare Kaon Decays and CP, TCP ViolationRare Kaon Decays and CP, TCP Violation

Vincenzo Patera*LNF/INFN

*From KLOE collaboration


CP Violation and SM tests TCP Violation tests Detour to Vus

Outlook & Conclusions

CP Violation and SM tests TCP Violation tests Detour to Vus


Foreword and outlineForeword and outline

The talk focuses on the experimental results of the last 2 years

Caveat: from an experimentalist point of view…!

Foreword: kaons again?In spite of a long history the K system is still a laboratory for the flavour physics, an interferometry system, a repository of all kinds of CP violation and can be a sensitive probe for NP.. Then:

YES, kaons again!

Notice: all the limits are at 90% C.L.

Blind analysis everywhere


Kaon and CP: classificationKaon and CP: classification

CP violation in the decay amplitute

CP violation in the decay amplitute

CP eigenstates ≠ mass eigenstates

CP eigenstates ≠ mass eigenstates

CP violation from interference of “DIRECT and MIXING”

CP violation from interference of “DIRECT and MIXING”

DIRECT MIXING or INDIRECT

INTERFERENCE

Ceccucci LP03

DIRECT CP firmly established after more than 30 yearsRe(’/) = (16.7±2.3)x10-4

KRe(’/)


Kaons, Unitarity Triangle(s) & CPKaons, Unitarity Triangle(s) & CP

11

21

21

23

22

32

AλiηρAλ

Aλ/λλ

iηρAλλ/λ

VVV

VVV

VVV

tbtstd

cbcscd

ubusud

The CP violation found its niche in the CKM mixing matrix and in its Wolfenstain parametrization. Up to O(4) the CKM is given by:

004.0)(

04.0

2.0

223

2

A

A

)1(52* AVV ttdts

A Unitarity Triangle stems from any complex unitarity costraint, but the unique measure of the CP in the CKM = 2xarea of any UT

JCP = Im(Vud*VusVts

*Vtd) ~ VusVud Im t

Unique CP parameter t probed by K or B sector differently: SM

test and/or NP sensitivity

If V*tdVts is complex CP is violated.. In shorthand:


The Unitarity Triangle and K rare decaysThe Unitarity Triangle and K rare decays

UnfortunatelyBR ranges from

10-8 to 10-11

KL→0e+e-

KL→0+-

KL→

KL→+-

KL→+-

KL→

KLee

KS→0e+e-

KS→0+-

KL→0

)0,1()0,0( )0,( 0

),(

K+→+-

Im t = A23 Re t= A23

The rare Kaon decays BR directly measure the UT, someone by itself, someone by the aid of ancillary K decays measurement.


Rare Kaon decays and SM test Rare Kaon decays and SM test

Yet, in spite of the experimental difficulty, the

rare K system:

Is theoretically clean (almost..)

Is highly sensitive to NP

Has different sensivity to NP wrt the B sector

Not only K ! NP sensitivity of KL0ll

system :Buras,Fleisher,Recksiegel,Schwab : hep-ph/0402112

SM test:sin2J/KS)

vssin2(K)


t and K++ t and K++

*1122

0411 10)1.17.7()(109.8)( AKBR SM

Negligible long distance effects 10-13

Hadronic matrix element via isospin rotation

K+e+0Reliable th. estimate from SM

Charm loop contribution = 0 1.4

*Isidori hep-ph/0307014

GOOD from a theorist point of view!!

)0,1()0,0( )0,( 0

K+→+),(

Im t = A23 Re t= A23


K++: E787/E949@BNLK++: E787/E949@BNL

end view

side view

KE949 wrt E787 improvement:

•Photon veto hermeticity•Tracking & energy resolution

•DAQ and trigger•Protons/sec from AGS

1210daccumulate

ratio

%factorduty

Tpintensity beam

KN

K 9.5

4

52

4025

8.1

3

41

70

E787 E949

Not optimal in 2002 run:•Spill duty factor

•Proton momentum•K/ electrostatic separators


K++@E949: detectionstrategy K++@E949: detectionstrategy

+ momentum in K+ frame (MeV)process Rate x 1010

K++ 0.77

K++ 2113000000

K++ 6343000000

K++0 327000000

+ from beam 25000000

Signal: a + from K+. No kinematic closure and

overwhelming bck.

700 MeV/c K+ stopped decay Detect pion from e decay chainMeasure everithing you can: range, momentum , energy, time

Signal: a + from K+. No kinematic closure and

overwhelming bck.

700 MeV/c K+ stopped decay Detect pion from e decay chainMeasure everithing you can: range, momentum , energy, time

12 weeks of data taking.Bck shapes modeled on data.

Each bck rejected by at least 2 independent cuts.


K++@E949the signalK++@E949the signal

E787 E949

NK+ 5.9x1012 1.8x1012

Accept.(20±2)x10-

3

(22±2)x10-

3

N. events 2 1

Total bck 0.14±0.05 0.30±0.03

K+ 0.064 0.068

K+ 0.032 0.216

Beam bck 0.050 0.014

E949

E787

Opening the box a new event is found

Background check: compare events predicted vs observed loosening one cut vs the other. Acceptance from MC verified

on K+ +0


K++@E949results K++@E949results

1096.0)( 1009.447.0

KBr

1030.189.0 1047.1)(

KBr

E949(02) = combined E787&E949.E949 projection with full running

E949 result (12 weeks of run)

E949 & E787 combined result

Analysis of the low momentum region (PNN2) in progress

Efforts to achieve on PNN2 a S/N 1 and sensitivity similar to PNN1

E949 was approved for 60 weeks of data taking more

stat?? (bad news…)


CP: Imt and KL0 CP: Imt and KL0

*11

2

4

3.2

110 10)5.06.2(10

Im

166

)(1048.1)(

ttt

SML GeV

mmKBR

Direct measure of Imt JCP

No long distance effects Only top loop contributionVery small theoretical error on SM

prediction Grossmann-Nir bound :

BR(KL0vv) < 4.4 x BR(K++)

< 1.4 x 10-9

*Isidori hep-ph/0307014

A dream for a theorist, a nightmare for an experimentalist. All neutral, 2/3 invisible final state: “Nothing to nothing”

)0,1()0,0(

KL→

Im t = A23

),(


KL0e+e-(+-) : KTeV @ TevatronKL0e+e-(+-) : KTeV @ Tevatron

• Charged particle momentumresolution < 1% for p>8 GeV/c;Momentum scale known to 0.01% from K.

• CsI energy resolution < 1% for E > 3 GeV; energy scale known to 0.1% from Ke.

•TRD system pion/electron ID

•KD with 0De+e- used

to normalize flux and acceptance.

KTeVMore than 20 years history..


KL0 @KTeV: the limitKL0 @KTeV: the limit

DataMC BG Sumn MC MCSignal MC

•1997 ’/ Data.•Analysis of events with Dalitz 0 decay.•Bck limited•4 order of magnitude higher wrt SM prediction

BR (KL)< 5.9x 10-7 (0ee)

PRD61(2000)


KL0 : E391a@KEK-PSKL0 : E391a@KEK-PS

Detector system

Pencil beam Detector with complete

veto systemo 4 coverage with thick

calorimetero Wide acceptance o Double decay chambero Operation in high vacuum

High PT + nothing selection

Step by step approach KEK-PS E391a JPARC

Pencil Beam

Firs detector designed for KL0veto, veto, veto..


Detector integration: Jan 22, 2004

Start of Run I data taking :Feb 18 2004

End Run I data takingJun 30 2004

KL0 : E391a detectorKL0 : E391a detector


KL0@E391a:Run I (2004)KL0@E391a:Run I (2004)

6- invariant mass (GeV/c2)

KL000

4- invariant mass (GeV/c2)

KL00

Expected

sensitivity by Run I:

4÷9x10-10

Results from Run I in fall 2004

Requesting Run II in 2005


CP : Imt from KL0e+e-(+-)CP : Imt from KL0e+e-(+-)

KL→0e+e-

KL→0+-

KS→0e+e-

KS→0+-

KL→0

Im t = A23

)0,1()0,0(

),(

The connection of the KL0e+e-() decays to t is not straightforward, but substantial

improvement of theory and experimental results have been in the last 2-3 years, expecially related

to ancillary modes


CP : Imt from KL0e+e-(+-)CP : Imt from KL0e+e-(+-)

KL0e+e-(+-) phenomenology:the decay amplitude has 3 ingredients:

3) CP conserving term via intermediate state

e+(+)

e-(-)

e+(+)

e-(-)

e+(+)

e-(-)

*Isidori,Smith,Underdorfer hep-ph/0404127Buchalla, D’Ambrosio,Isidori Nucl.Phys.B672(2003)

1) Direct CP term Im t , dominated by short distance

dynamics

2) Indirect CP term due to KL-KS mixing

Amplitude 2) can be extracted via from KS0e+e-(+-) decay while 3) can

be derived from KL0 data Direct and Indirect CP amplitudes can

interfere. In the past 2 years both precise

calculation for 1)* and new data for

KS 0e+e-(+) and KL0 appeared on the market


From KL0l+l- to Imt : KS0l+l-From KL0l+l- to Imt : KS0l+l-

330

)()()(

0020

llKBRllKBRllKBR S

SS

LmixCPVL

330

)()()(

0020

llKBRllKBRllKBR S

SS

LmixCPVL

e+(+)

e-(-)

Assuming the VMD the KS BR can be predicted of the

order:

*Buchalla,D’Ambrosio,Isidori Nucl.Phys. B(2003)

BR(KS0e+e-) 5 x10-9

BR(KS0+-) 1 x10-9

KL0l+l- CP mixing contribution ( and

interference) can be evaluated via and the corresponding KS0l+l- amplitude*.


LKr Calorimeter:(E)/E (E)/E 3.2%/√E 3.2%/√E 9%/E 9%/E 0.42%0.42%(t) (t) 265 ps for 50 GeV e 265 ps for 50 GeV e

Spectrometer:pT kick ~250 MeV/c(P)/P (P)/P 0.48% 0.48% 0.009 P[GeV/c] 0.009 P[GeV/c]%%

Muon system:Muon system:(t) (t) 350 ps 350 ps

M(00) ~ M(+-) ~ 2.5 MeV

KS0e+e-(+-) : NA48/1 @CERN KS0e+e-(+-) : NA48/1 @CERN

KS beam : 2000 (only s) and 2002

run

More than 20 years history..


From KL0l+l- to Imt : KS0l+l-From KL0l+l- to Imt : KS0l+l-

Dataset: 3.51 x1010 KS decays with < 2.5S and 40<EK<240

GeVMain Backgrounds

For e channel: KS00D with a

lost:rejected by mee> 0.165 GeV/c2

cut

time accidentals , mainly from lv + 00(0): studied from time side bands

KL,Se+e- Greenlee background

due to double radiation:

estimated from 2001 KL run

(statistics x10). Negligible for the channel

Bck source Events

KL,Se+e- 0.08+0.03-0.02

Accidentals 0.07+0.07-0.03

Total bck 0.15+0.10-0.04

Bck source Events

KL,S+- 0.04+0.04-0.03

Accidentals 0.18+0.18-0.11

Total bck 0.22+0.18-0.11

KS0e+e-

KS0+-


From KL0e+e- to Imt : KS0l+l-From KL0e+e- to Imt : KS0l+l-

BR(KS ee) = 2.8 92.3(5.8 0.8 ) x 10syststat

[PLB576 (2003)]

Assuming vector interaction and unity form factor for electron channel to recover the mee>0.165 GeV/c2

MK(G

eV

)

M(GeV)

7 signal events

M(GeV)

M

(GeV

)

6 signal events

BR(KS 1.4 91.2(2.9 0.2 ) x 10syststat

KS0e+e- KS0+-

CERN-PH-EP/2004-025


KL0e+e-(+-) : SM predictionKL0e+e-(+-) : SM prediction

The last ingredient is the CP conserving amplitude of KL0l+l- . It can be parametrized

in term of :

BR(KL0) =(1.36±0.03stat±0.03sys±0.03nor)x10-6 *

=(1.68±0.07stat±0.08sys)x10-6 **

e+(+)

e-(-)

0++,2+

+

*Isidori,Smith,Unterdorfer hep-ph/0404127

**Friot,Greynat,de Raphael hep-ph/0404136

2

4,

4,

int,,0

10

Im

10

Im)(

tedir

teemix

ecpcSML CCCCllKBR

The t parameter dependence is embedded also in the interference term. The positive sign of the interference term seems to be theoretically preferred*,**

BR(KL0) BR(KS0ll)

*NA48 PLB2002 **KTeV PRL1999

Finally:

theory


KL0e+e-(+-) : SM predictionKL0e+e-(+-) : SM prediction

BR(KL0 e+ e-)SM x 1011 = (3.1 or 1.3)

±1.0

BR(KL0 + -)SM x 1011 = (1.8 or 1.2)

±0.3

Taking Im(t) = (1.36±0.12)x10-4 a prediction can be done for BRs:

Interf (-)

Interf (+)

Contribution to BR

BRs vs Imt

Main uncertainties come from experimental inputs and (less)

from CPC contribution theoretical evaluation (

channel)

x10-12


KL0e+e- @KTeV: backgrounds KL0e+e- @KTeV: backgrounds

Background due to KL0 ,

KLDKLev is removed

using TRD and cut on charged momenta and event pt

2

•Irriducible background with same final state of the signal from Greenlee double radiation: KLe+e-

with a BR=(6.31 ± 0.14 ± 0.42)x10-7

•The background has radiative s collimated with e±. Discrimination via minimum angle between and e

•The signal has almost isotropic s in the 0 frame. Discrimination via angle between and KL in 0 frame

1997+1999 dataset: 6.7x1011 KL

Mee (GeV/c2)

M

(G

eV

/c2)

1999data

Signal: two s and two opposite tracks with e IDs


KL0e+e- @KTeV:resultsKL0e+e- @KTeV:results

Opening the box after these cuts 1 events is found out of 1 ±1/3

background events expected. The limit obtained is:

BR(KL → 0 ee ) < 2.8 × 10-10 @90%CL

Mee (GeV/c2)

M

(G

eV

/c2)

1999data

Phys. Rev. Lett. 93, 021805 (2004) 1997+1999 data

2 order of magnitude lower than the previous limit but 1 order of magnitude higher then the SM prediction. Future

measurement will need improvement both in KL statistic and in background rejection


KL0+- @KTeV: backgroundsKL0+- @KTeV: backgrounds

A similar analysis has been made for KL0+- on the 1997

dataset: 2.7x1011 KL

Signal: two s and two opposite tracks with IDs Background mainly due to KL0,KLv +2acc and to

double radiative KL+-.

the Greenlee bck is less severe than for e+e- case ( the radiates less):

BR(KL+-) = (10.4+7.5-5.9

±0.7)x10-9

M (GeV/c2)

Pt2 (

GeV

/c)2

Kinematic costraint on inv. mass and pt of total event

single out the signal


KL0+- @KTeV: resultsKL0+- @KTeV: results

BCK mode Expected ev

total 0.87±0.15

KL+- 0.373±0.032

KL0+- 0.268±0.096

KLacc 0.161±0.093

Even

ts/1

MeV

M (GeV/c2)

Opening the box 2 events were found in the signal region with 0.87

expected

The limit obtained is:

BR(KL→ 0 ) < 3.8 × 10-10

@90%CL

Phys. Rev. Lett. 84, 5279-5282 (2000)1997 data

Also the KL0+- exp. limit

has been pushed down by orders of magnitude but is still ~1 order of magnitude above SM


Kaon rare decays and Re(t) Kaon rare decays and Re(t)

)0,1(

•The BR(KL) is almost saturated by the absortive amplitude, computed from measured BR(KL) with small error. •The (tiny) short distance contribution of dispersive amplitude is related to :

),(

9

255.1

2 10040.0170

)()2.1()(

cbtt

SDL

V

GeV

mmKBR

The long distance contribution to dispersive amplitude, via KL*, KL**, must be

extracted from KLl+l- and

KLe+e-l+l-dataKL→+-

KL→

KL→ee)

KLeeee(

KL→

KL→ee)

KLeeee(

Ret= A23


Re(t):KL and E871@BNLRe(t):KL and E871@BNL

Accuracy limited by the error (th. & exp.) on dispersive amplitude evaluation

BR(KL) = (7.18 ±0.17)x10-9

< 0.33 @90% C.L. PRL84(2000)

signal

bck

E871Muon hodoscope

Lead GlassCalorimeter

CerenkovTrigger

Scintillator

NeutralBeam Dump

Drift Chamber 5 & 6

Straw Chamber 1 & 2

Drift Chamber 3 & 4


UT and CP from K: status summaryUT and CP from K: status summary

K++ : BR twice of SM prediction but within statistical error. (new run?)

KL0 : exp. limit far

away from SM, but E391a is getting closer.

KL0ll : experimental

limits a factor 10 above SM. New exp. needed (may be KL0 easier?)

KL : sensitivity to limited both by theory and by exp. error on KL→ f.f.

Courtesy of G.Isidori

New generation of dedicated

experiments (& beams) needed.


OutlineOutline

CP Violation and SM tests TCP Violation Detour to Vus Outlook & Conclusions



Main uncertainty on CPT violating parameter is due to the

error on A(KS30) and on |000|=A(KS30)/A(KL30)

contribution to :

Rare Kaon decays and TCPRare Kaon decays and TCP

ff

LS

LS im

i )Im()Re()(

21 ,

A TCP test typical of the Kaon system can be derived from the KL,S amplitudes imposing unitarity via the Bell-Steinberger

relation:

*1f S L

S

A K f A K f

The experimental limit on BR and in literature are:

BR(KS30) < 1.4x10-5 (SND, PL B459 1999)

Im = (2.4 ± 5.0) × 10-5 CPLEAR ’99

0000

000 3Im

L

SLKBR


KS30 : KLOE@DANEKS30 : KLOE@DANE

KLOE run 2001-20020.45 fb-1 1.4x109 decays

Foreseen 2 fb-1 2005

KLKS 106 /pb-1 p* = 110 MeV/cS = 6 mm L = 3.4 m

•The decay at rest provides pure, monochromatic, back to back kaon beams in 1-- quantum state •Tagging: observation of KS,L signals presence of KL,S

•KL,S beams in the same detector at the same time

K+K- 1.5 106 /pb-1 p* = 127 MeV/c ±= 95 cm

KKLL tag tagByByTOFTOF

KKSS ee

m=1019.4 MeVThe KS→30 is a CP violating

decay, with a BR in the SM ~1.9x10-9. The -factory provides

an abundant pure KS beam


KS30 : KLOE@DANE KS30 : KLOE@DANE

p/p = 0.4 % (tracks with > 45°)

vertex ~ 1 mm

(M) ~ 1 MeV

E/E = 5.7% E(GeV)

t = 54 ps /E(GeV) 50 ps (relative time between clusters)

L() = 2 cm ( from KL )

Drift chamber (4 m 3.3 m)90% He + 10% IsoB, CF frame12582 stereo sense wires

Electromagnetic calorimeterLead/scintillating fibers 4880 PMT’s

Superconducting coil (5 m bore)B = 0.52 T ( B dl = 2 T· m)


KS30 @KLOE: results KS30 @KLOE: results

4 candidates in signal box with 3.2±1.4±0.2 expected by bck (MC)

BR(KS30 ) < 2.1x10-7 @90% CL (KLOE04 PRELIMINARY)*

BR(KS30) < 7.4×10-7 @90%C.L. (NA48 ’04 hep-ex/0408053)

KS tagged by KL which

interacts on EMC (~30%). The KL interaction are

identified by energy and . KS signal selected by 6 sMain bck from KS20 + acc.Event fitted in 30 and 20 hyphothesis

6

000Im 6.34 10 @90% . .C L

Im() = (-0.2±2.0)x10-5

Accuracy limited by A(KL,S→+-)

23

• Data• MC 2

22

*This conference


OutlineOutline




Detour: a look at the Vus sagaDetour: a look at the Vus saga

BUT (in 2002) ... BRs obtained from fit to ratios of BRs. Errors and

central values to be checked 3/e3 disagreement with measured ff slopes, 4% or

3 Unknown inclusion of radiative processes

222

3

5

3(

191 (0)

2)EW K us K

KK

F S fV IG M

No theory ! No ’s ! No hyperons ! Only K measurements !

2002: after a huge revision of the Vud determination (th. & exp.)

according to PDG: |Vud|2+|Vus|2+|Vub|2 |Vud|2+|Vus|2 = 1-2.4The preferencial source of Vus being Kl3 decay (Ko & K+):

theory

From experiment: BRs, lifetimes and form factors to compute and IlK


Vus after 2002: new measurementsVus after 2002: new measurements

2003 – E865: BR(K+ e2004 – KTeV: main 6 KL BRs and Kl3 f.f.

2004* – NA48: BR(KLe), BR(K±0e±) and

f.f.2004* – KLOE: BR(KSev) , BR(KLl) and

(KL)

fully inclusive measurements: Ke(),

*this conference

**Czarnecki,Marciano,Sirlin hep-ph/0406324

The new Vus seem to amazingly agree with unitarity in spite of

a bit of “entropy”.. For example in the KL(e) case:

L(10-7s) f+(0) f.f.

KTeV 51.50 0.961quadraticmeasured

NA48 51.50 0.981linear

measured

KLOE 51.35 0.961 as KTeV

KSe3 KL3 KLe3 KLe3 KLe3 K+e3 K+e3

**|Vus|

KLOENA48KTeVE865


Vus saga: BRs vs form factorsVus saga: BRs vs form factors

BUT agreement of new Vuss gets even better if the same ingredients (but the BRs) are used for Vus*→BRs seem ok!

Less agreement on new measured form factors. Notice: linear vs quadratic f.f. can account as much as 1% on Vus.

*F.Mescia,A.Antonelli, this conference

from PDG04f.f. by KTeV.

Vu

s x f

+(0

)

KTeV NA48 ISTRA**

+’ x10-

3

20.64 1.75

28.81.2 23.24 ± 1.52

+’’ x10-3

3.20 0.69 0 1.62 0.79**2”ISTRA=”KTeV

2004 results

•PDG02


Vus and Kaons: something newVus and Kaons: something new

Alternative method to extract Vus from K±±: given fK/fp

computed on lattice, then:

(K2) is from a 1972 measurement and PDG fit. It is not known

what radiative contribution is retained. Adding contribution of radiation |Vus| goes up! New measure? (KLOE,NA48,ISTRA)

♦ ffKK/f/f-1=0.210(4)(13)-1=0.210(4)(13) |V|Vusus| =(0.2219| =(0.2219((MarcianoMarciano hep-ph/0406324) hep-ph/0406324)((MILCMILC hep-lat/0407028) hep-lat/0407028)

lattice theoryexp


OutlineOutline

CP Violation and SM tests TCP Violation Detour to Vus


CP Violation and SM tests TCP Violation Detour to Vus



Outlook: KOPIO@BNLOutlook: KOPIO@BNL

•Microbunched flat beam: measure velocity (momentum 800 MeV/c) of KL

•Hermetic high efficiency veto•Measure time, position and energy •High vacuum decay region

Aim to collect 60 KL→0 events with S/B~2

(Im t to 15%)

Approved & fundedAdvanced R&D

Construction start 2005 (?)

KL→0


Outlook: E391@JPARKOutlook: E391@JPARK

Evolution of the E391a@KEKPencil beam conceptTarget sensitivity well beyond SM prediction for

KL0Start in 2009(?)KEK-PS AGS JPARK-1

E(Gev) 12 24 30

Duty cycle(s)

4.0 6.4 3.4

I(A) 0.1 1.63 9.5

spill(s) 2 4.1 0.7

Duty factor 0.50 0.64 0.20

Rate (1012/s) 1.3 16 286

JPARK

KL0


Outlook: NA48/3@CERNOutlook: NA48/3@CERN

Based on upgrade of NA48/2 detector

Unseparated, positive beam of 75 GeV/c with P/P~1%

Upstream detector to identify kaons and measure K momentum

Hermetic photon vetoes Finely segmented Hadron

Calorimeter/Muon veto• EoI exists• Intense R&D activity in 2004 • time schedule Villars Workshop in fall 2004

Goal: About 50 Events with a Goal: About 50 Events with a S/B of 10:1 in 2 years of data S/B of 10:1 in 2 years of data

takingtaking

K+ +


Outlook: further initiatives/projectsOutlook: further initiatives/projects

K+ physics at the JPARK charged beam (2009)

Pure KS beam – factories (schedule?)

Four LOI presented addressing K++ , T violation in K+

3 , rare K+ decays , K+e3 BR with high

statistic

Clean environment to study KS decay: CP, TCP violation and KS0l+l- . DAFNE-2 (?) project, dedicated workshop

in Alghero in 2003

OKA@Protvino: RF-separated K± beam project (schedule?)

Rare K± decays physics, direct CP violation in K± ±± and K±±


ConclusionsConclusions

The field of rare kaon decays is quite active. A generation of detectors is now mature (’/, LFV, T violation) and a new

round of initiatives is approaching.

Projects are addressing both neutral and charged K. Despite of the experimental difficulty this item will be on the spot in the next years.

New (coherently on KS & KL) projects/ideas are needed to explore the KL,S0ll system. Interference with mixing CP amplitude enhance both direct CP signal and sensitivity to NP. Mostly exp. limited..Why not? (expecially the mode..)

The Vus saga seems to have an happy end. New results in better agreement with unitarity. Focus now on f.f. and K0, K+ lifetimes


Further results on rare K decays and TFurther results on rare K decays and T

T violation: E246@KEK-PS. Final results (2004) from K+0:PT = (- 1.7 ± 2.3stat ± 1.1syst)x10-3

Lepton Flavor Violation: KLe E871@BNL.

BR(KL→ e) < 4.7 10-12 90% CL

Lepton Flavor Violation: K++e- E865@BNLBR(K+++e- ) < 1.2 x 10-11

Dalitz decay @ KTeV : BR(KL→ee) = (2.69± 0.24± 0.12) x 10-9

BR(KL→eeee) = (4.16 ± 0.13 ± 0.13 ± 0.17) x 10-8

And many more……..

TCP violation: KS semileptonic asymmetries @KLOEAS = (2 ± 9stat ± 6syst) x 10-3 KLOE2004 (preliminary)


Spare materialsSpare materials


OutlineOutline

CP Violation TCP Violation T Violation Lepton Flavour Violation Outlook & Conclusions


Caveat: all that from an experimentalist point of view…!



K decays and T violation: E246@KEK-PSK decays and T violation: E246@KEK-PS

SM expectation: PT 10-7

Final results (2004) from K+:PT = (- 1.7 ± 2.3stat ± 1.1syst)x10-3

Side product from K+→ : PT = (-6.4 ± 18.5stat ± 1.0syst)x10-3 *

transverse polarization in K+

3

Stopped K+ experiment with a SC toroidal spectrometer Measurement of all decay kinematics directions+ separation from e+ by TOFEvents selected by +,0 coincidence

*Phys.Lett. B562 (2003) 166]


OutlineOutline



Caveat: all that from an experimentalist point of view…!



LFV: KLe E871@BNLLFV: KLe E871@BNL

BR(KL→ e) < 4.7 10-12 90% CL Signal region

Control region0.1 bck event expectedin the 1995-96 data sample , no events observed :

Main background from K0L→ e with → decay in

flight and e scattered on vacuum window and first tracking station. Rejection by cut in M(e) vs pt

2 plane


LFV: K+e- E865@BNLLFV: K+e- E865@BNL

Dataset 1995-96-98

Main background from time accidentals, estimated by time sidebands = 8.2±1.9 events expectedLikelihood analysis built on beam parameters, PID, timing and three-track invariant mass

BR(K+++e- ) < 1.2 x 10-11

E865

Far away from SM expectationsHard competition by experiment


TCP test : KSe0 asymmetry@KLOETCP test : KSe0 asymmetry@KLOE

e e

Emiss–cPmiss(MeV) Emiss–cPmiss(MeV)

AS = (2 9stat 6syst) x 10-3 KLOE2004 (preliminary)

AL = (3.322 ± 0.058 ± 0.047) x 10-3 KTeV 2002

Efficiency evaluated using KL edecaying close to IP: e+) = (24.10.1 0.2)% e-) = (23.60.1 0.2)%

PID from TOF

)()(

)()(

,,

,,,

eKeK

eKeKA

LSLS

LSLSLS

AS -AL= 0 if TCP holds

TCP test is also made using the KL,KS semileptonic asymmetries:

First measuremen

t


Vus & BRs: what is actually measured?Vus & BRs: what is actually measured?

Exp Quantity measured channel

KTeVR(e3/3), Re3/00), Re3/000),

Re3/0-+), R(00/000)

KLe

KL

KLOE

Absolute BR(K3) using KS tag KL

Absolute BR(Ke3) using KS tag KLe

BR(KSe)/BR(KS) KSe

E865 BR(K±e±0D)/BR(K±( ±0

D+ ± 0D+ ±0

D))*K+e+

NA48BR(K±e±0

D)/BR(K±( ±0D+ ± 0

D+ ±0D))*

K+e+

BR(Ke3)/BR(k 2 tracks)BRe3/BR KLe

*BR(±0) PDG=21.13±0.14 dominated by 1 exp: CHIANG (1972) 21.18±0.28

R(a/b) = BR(a)/BR(b)

A lot of diffferent normalizations to PDG fit, PDG average, WA, etc. etc. are around

0Dee


Rare Kaon decays and TCP: KS30 Rare Kaon decays and TCP: KS30

20 0 93 3 1.9 10SS L

L

BR K BR K

BR(KS30) < 7.4 × 10-6 @90%C.L. (NA48 ’04hep-ex/0408053)

Within SM the KS30 violates CP and can be computed as:

NA48 searched for this decay exploiting the interference of KL-KS beams to enhance the rare KS30 decay with the much more abundant KL 30. The decay intensity is then

given by:

2

)(

000000

2

000

)sin()Im()cos()Re()(

)(LS

SL

emtmtpD

eetI tt

D(p) is the dilution factor to the KS to KL beam. Using he 2000 data the limit on the BR(KS→30) obtained is:


K++@E949new event K++@E949new event


Improved photon veto

detectors γline beam New

2.3 add

region barrelin r calorimete New

0

X

rejection π0

E949

E787 2

Rejection to background as a function of acceptance for E787 and E949. better rejection at 80% of nominal acceptance.

2~

2K

γNew detectors in blue.


Trianglety on Unitari )(K ofImpact B

By courtesy of G. Isidori

Central value [dashed], 68% interval [dot-dashed], 90% interval [solid](including theoretical uncertainties)

3352 1008110240:)1(

0271000550

.λ.iλAVV λ

.V.

t-

td*

ts

td


From KL0+- to Imt : KS0+-From KL0+- to Imt : KS0+-

Main backgrounds from accidentals and radiative KL decay

The Greenlee background in the signal acceptance is reduced wrt the KLee case. Can be safely evaluated from KTeV

measurement:In the signal box 0.18+0.18

-0.11 events are expected

The 2 main source of accidentals are

KL→ + KS→

KS→ + KS→Contribution to signal estimated from time side band : 6 events in ~125 ns. In signal time window (3 ns) are

expected 0.18+0.18-0.11 of background

M(GeV)

M

(GeV

)

Out of time ev. (125 ns)


NA48 Detector & Data Taking NA48 Detector & Data Taking

1997

1998

1999

2000

2001

2002

2003

NA48: ’/

’/

’/

’/ lower inst. intensity

NA48/1 KS

NA48/1: KS

KL

no spectrometer

NA48/2: K

1996Total: 5.3M KL00

Magnetic spectrometer

Liquid krypton EM calorimeter2004NA48/2: K


KL0e+e- @KTeV: backgrounds KL0e+e- @KTeV: backgrounds

Rejection of the bck can be achieved exploiting the different kinematics:

•The background has radiative s collimated with e±. Discrimination via minimum angle between and e min

•The signal has almost isotropic s in the 0 frame. Discrimination via angle between and KL in 0 frame |cos()|The region where the bck is

concentrated is cut away.

KL0e+e-

min

|cos()|

KLe+e-

min

|cos()|


Re(t):KL and KL Dalitz decayRe(t):KL and KL Dalitz decay

2 2 2 22 2 1 2 1 21 2 2 2 2 2 2 2 2 2

1 2 1 2

( , ) 1( )( )DIP

q q q qf q q

q m q m q m q m

Two LD dispersive amplitude parametrizations:

BMS**: pseudoscalar/vector contributions: K

*

DIP*: general parametrization compatible with CHPT expansion: DIPDIP

DIP=-1+(3.1±0.5)K*

*D’Ambrosio,Isidori,Portoles PLB(1998) **Bergström, Massó, Singer, 1983

KL→ee) K*, DIP KLeeee(

DIP

Measures dominated by KTeV and NA48, no enough statistic for DIP

K

*


Unitarity Triangle(s): B vs K sectorUnitarity Triangle(s): B vs K sector

UT from K

UT from B

UT from K

UT from B

Not yet on scale!

Kaon UT is extremely squeezed due to t=V*tdVts .

Unique measure of the CP in the CKM = 2xarea of

all UT JCP = Im(Vud*VusVts

*Vtd) ~ VusVud Im t

Unique CP parameter t probed from K or B sector

with different loops: SM test and/or NP sensitivity

ICHEP04 Beijing 16-22 aug 2004 Rare Kaon Decays and CP, TCP Violation Vincenzo Patera* LNF/INFN...

Documents

Transcript of ICHEP04 Beijing 16-22 aug 2004 Rare Kaon Decays and CP, TCP Violation Vincenzo Patera* LNF/INFN...