CPANDT CPANDT M.S.Sozzi M.S.Sozzi VIOLATION VIOLATION - - PowerPoint PPT Presentation

CPANDT CPANDT VIOLATION VIOLATION WITHKMESONS WITHKMESONS

M.S.Sozzi M.S.Sozzi UniversityofPisa UniversityofPisa

August 30th, 2007 - Time and Matter 2007 - Bled, Slovenia

TAM07 CP/T violation with K M. S. Sozzi

Outline

• Introduction
• DirectCPviolation
• IndirectCPviolation
• CPVinchargedKdecays
• Tviolation
• Thefuture
• Conclusions

Somebyproducts

TAM07 CP/T violation with K M. S. Sozzi

OfKaons,Flavour andCPviolation

Kaons:thelightestkindofflavoured matter

• Thebirthoftheflavour physicspuzzle
• Thefirstfailureofadiscretesymmetry
• Thematter"antimatterasymmetry

Alargeandsignificantpartofparticlephysics…

TAM07 CP/T violation with K M. S. Sozzi

CPviolation

The“C” requiresHEP experiments Thesmallest symmetryviolation Anecessaryingredient forbaryogenesis Linkedtoflavour (atleastintheSM) MustbepresentinNewPhysics

TAM07 CP/T violation with K M. S. Sozzi

CPandTviolation

Evenmoreintriguing andmysterious: theinterplayofCPandT throughthe“rock"solid” (?) CPTtheorem

TAM07 CP/T violation with K M. S. Sozzi

Kaons asthe minimalflavour laboratory

Kaons remainaprivilegedobservatory forflavour physicsphenomena

• All thefeaturesofflavour physicsare

present(i.e.allkindsofCPviolation–

• fsamesizeasinB)
• Verysimple (minimal)system
• Verynicelyaccessible experimentally
• Veryhard fortheorists…

TAM07 CP/T violation with K M. S. Sozzi

SearchingforCP/TviolationwithK

PT(K53) Tripleprod. Measureofnon"zeroT"oddquantities P(K0→K0)≠ P(K0→K0) Testoftime"reversibility ∆g(K→3π) Differencesinthepartialdecaywidthsordecay propertiesofparticlesandantiparticles KL → ππ and Ks → πππ SearchforphysicalstatesnotbeingCP eigenstates (non"exponentialdecayofCP eigenstates) K2→ππ TransitionsamongCPeigenstates withopposite eigenvalues

TAM07 CP/T violation with K M. S. Sozzi

Despitegreatefforts: nonewsonCPviolationfor36years… Thelong"standingsuperweak scenario

CPV:thelonghiatus

K0 K0 GSW ≈ 10"7 GF IsCPviolationanintrinsicproperty

• fweakinteractions,orisitrather

apeculiareffectlinkedtoquasi" degeneratestatemixing?

“Atpresentourexperimental understandingofCPviolationcanbe summarizedbythestatementofa singlenumber”.(J.Cronin,10.12.1980)

TAM07 CP/T violation with K M. S. Sozzi

DirectandindirectCPVinSM

Indirect CPviolation (K0"K0 mixing):ε ≈ 2.2⋅ 10–3 Direct CPviolation (decay):ε’ KL ∝ K2+ε K1 ππ KL ∝ K2+ε K1 ππ

Could be superweak Cannot be superweak

TAM07 CP/T violation with K M. S. Sozzi

ThesearchfordirectCPviolation(CPVintheK→2π decayamplitude):alongseriesofprecisioncounting experiments(theonlyworkingapproachsofar) The(inconclusive)legacyofthe NA31(CERN)andE731(FNAL)experiments ThewholeofKphysicsinthelastdecade spunofffromthiscentralexperimentalprogram

ThequestfordirectCPV

) / ' Re( 6 1 ) ( ) ( ) ( ) (

2 2 00

ε ε π π π π π π π π η η − = → Γ → Γ → Γ → Γ =

− + − + − + L S S L

K K K K

TAM07 CP/T violation with K M. S. Sozzi

KTeV atFermilab

MainInjector(120GeV)p DoubleKL beam(<p>=70GeV/c) RegeneratedKS PureCsI calorimeter Datatakingin1997and1999 100physicists,12USA/Japan institutions

TAM07 CP/T violation with K M. S. Sozzi

NA48atCERN

SPS(450GeV)p KS andKL beams(<p>=100GeV/c) KS taggingbytime"of"flight LiquidKryptoncalorimeter Data"taking1998"1999"2001 130physicists,16Europeaninstitutions

TAM07 CP/T violation with K M. S. Sozzi

DirectCPviolation:ε ε ε ε’/ε ε ε ε

1999:proofofdirectCPviolation(after36years!)at>7σ NA48 (1997"2001):finalresult KTeV (1997"1999):½ statistics(1997) χ2=6.2/3,consistency10% Roomforimprovement(…)

Re(ε ε ε ε’/ε ε ε ε)=(16.3± 2.2)W 10"4 Worldaverage: Re(ε ε ε ε’/ε ε ε ε)

• 2005EPSPrizetothe

NA31collaboration 2007APSPanofsky Prizeto Italo Mannelli (Pisa),HeinrichWahl(CERN) andBruceWinstein (Chicago)

TAM07 CP/T violation with K M. S. Sozzi

DirectCPV: themeaningofit

6

10 ) 82 . 04 . 5 ( ) ( ) ( ) ( ) (

− − + − + − + − +

× ± = → Γ + → Γ → Γ − → Γ π π π π π π π π K K K K

ThefirsttestoftheCKMparadigmforCPviolation CPVisauniversalpropertyofweakinteractions, notapeculiarityofneutralkaons

• Also:theevidenceofdirectCPVmakesthe

anti"gravityargumentuseless

TAM07 CP/T violation with K M. S. Sozzi Newmeasurements

ε’/ε theoreticalpredictions(SM)

ε ε ε ε’ confrontstheSM

ExperimentalvaluesarecompatiblewiththeSM (accidentallyquasi"superweak) ε’/ε measuredto10"15% WaitingforlatticeQCDforKtobecomealso aquantitative testofSM. Thequalitative importanceofε’/ε ≠ 0 clearlytrascends the(dire)theoreticaldifficultiesinrelatingpreciselysuch quantitytotheStandardModelparameters

TAM07 CP/T violation with K M. S. Sozzi

KLOE(1999=2007)

AtFrascati DAΦNEΦ"factory withseparatee+e" ringsand 12.5mradcrossingangle workingat√s =m(Φ) =1019.4MeV Integratedluminosity: ~2.5fb=1 1999"2006 (~ 2.5W 109 KSKL events)

TAM07 CP/T violation with K M. S. Sozzi

CPVbyinterferometry

• t1

t2 f1 f2 KS,KL KS,KL Φ

( )

) cos( 2 2 1 ) , ; , ( 2 1 ) ; , (

2 1 2 / 2 1 2 2 2 1 2 2 1 2 2 1 2 1

φ φ η η η η − + ∆ ∆ − + Γ = ∆ = ∆

Γ∆ − ∆ Γ − ∆ Γ − ∞ ∆

∫

t m e e e K f K f dt t t f f A t f f I

t t t S S t

S L

Inprinciplemanydifferentquantitiesmightbe measured,e.g.f1=π+π–,f2=π0π0 ⇒ Re(ε’/ε),Im(ε’/ε) Highstatisticsrequired,noresultsavailableyet DecaysfromentangledKS"KL states(Φ decays)

TAM07 CP/T violation with K M. S. Sozzi 3

10 ) 055 . 322 . 3 ( ) (

−

⋅ ± = e

L

δ

2

1 ) Re( 2 ) ( ) ( ) ( ) ( ) ( ε ε ν π ν π ν π ν π δ + = → Γ + → Γ → Γ − → Γ =

− + + − − + + −

• L

L L L L

K K K K

IndirectCPV:ε and|η+"|

PrecisemeasurementsobtainedbyKLsemi"leptonic chargeasymmetry inKTeV andNA48usingafew100Mdecaysperexperiment:

(assuming CPT)

• ε

ε ε π π π π η ≈ + ≅ → → =

− + − + − +

' ) ( ) (

S L

K A K A

Also: Standard(mostlyindirect) CPviolationparameter

(world average)

TAM07 CP/T violation with K M. S. Sozzi

CPLEAR(1990=96)

200MeV/c antiprotonsatCERN Measureasymmetrieswith flavour"taggedneutralkaon state

(cmp.Bphysicsathadron colliders)

t f f t f iHt CP iHt CP iHt CP iHt CP CP

e mt e K e f K e f K e f K e f A

) ( 2 2 / ) ( 2 2 2 2

1 ) cos( 2 ) Re( 2

Γ − Γ Γ − Γ − − − −

+ − ∆ − = + − = η φ η ε

π+π − π0π0 π0π0π0 π+π −π0

(Indirect)CPviolationin2π finalstates– nosignalin3π finalstates

TAM07 CP/T violation with K M. S. Sozzi

KLOE:|η+"|

• Subsample of2001"2002data

DirectmeasurementofBR(KL→π+π–)/BR(KL→π5ν) UsingmeasurementsofKS (PDG04) andKL (KLOE06)lifetimes,and BR(KS→π+π–) (KLOE06) SubtractingCP"conserving(DE)

KL→π+π–γ component BR(KL→π+π–)=(1.963± 0.012stat. ± 0.017syst.)× 10–3

45KKL→π+π– CPVevents

3

10 ) 013 . 219 . 2 (

− − +

⋅ ± = η

Phys.Lett.B638 (2006)140

TAM07 CP/T violation with K M. S. Sozzi

NA48:|η+"|

Dedicated2"dayrunin1999 DirectmeasurementofBR(KL→π+π–)/BR(KL→πeν) 47KKL→π+π– CPVevents 0.5%well"understoodbackground

• R=BR(KL→π+π–)/BR(KL→πeν)=(4.835± 0.022stat. ± 0.016syst.)× 10–3

0.33% +0.04% Total 0.10% MC statistics 0.10%

Radiative corrections

0.20% Energy spectrum 0.11% –1.29% Trigger efficiency 0.18% +0.48% Muon ID 0.03% –0.49% K2π background 0.05% +1.34% Particle ID Uncertainty Correction Uncertainty source

CorrectionsanduncertaintiesonR

Phys.Lett.B645 (2007)26

TAM07 CP/T violation with K M. S. Sozzi 3

10 ) 012 . 223 . 2 ( ) ( ) ( ) ( ) (

− − + − + − +

⋅ ± = → → =

L S S L

K K K BR K BR τ τ π π π π η

3

10 ) 010 . 229 . 2 (

−

⋅ ± = ε

NA48:|η+"|

Phys.Lett.B645 (2007)26

• UsebestsinglemeasurementsofKS (NA4802)andKL (KLOE06)

lifetimes,BR(KL→πeν)(NA4804++) andBR(KS→π+π–) (KLOE06) SubtractingCP"conserving(DE)KL→π+π–γ component Subtractingε’ andassumingrealε’/ε thevalueofε isobtained

(PDG07,inluding |η00|)

TAM07 CP/T violation with K M. S. Sozzi

CPVinhadronic KSdecays

NoCPVseenyet

3π statesare(predominantly)CP"odd Estimate(indirectCPV):ΓS(3π)≈ ΓL(3π)|η|2,or BR(KS → 3π0)≈ BR(KL → 3π0)|ε|2 (τS/τL)≈ 1.9W10−9 Hadron machines:lookforKS"KL interference. NA48/1(2005,assumingCPT):BR(KS→3π0)<2.3×10−7 (90%CL)

with5+100millionKdecays.

Phi=factories:searchfortaggedKS→3π0 decays. KLOE(2005):BR(KS→3π0)<1.2×10−7 (90%CL) with2signalevents. Improvementsexpectedfromhere…

TAM07 CP/T violation with K M. S. Sozzi

KLOE:δS(e)

• BR(KS→πeν)=(7.028± 0.092)× 10–4

FirstmeasurementofKS semi"leptonic decays(KS→π5ν alsoseen):

3 syst stat

10 ) 9 . 2 6 . 9 5 . 1 ( ) ( ) ( ) ( ) ( ) (

− − + + − − + + −

⋅ ± ± = → Γ + → Γ → Γ − → Γ = ν π ν π ν π ν π δ e K e K e K e K e

S S S S S

2001"2002data(410pb"1): 13Kevents

CPTtestbycomparisonto δL(e)(stillfarfrombeing significant)

Phys.Lett.B636 (2006)173

(Indirect)CP"violating chargeasymmetry: π–e+ν π+e–ν

TAM07 CP/T violation with K M. S. Sozzi

TheBell"Steinberger legacy

Unitarity imposesarelationlinking(indirect) CP" andCPT"violatingparameterstoallthe physicaldecayamplitudes FruitfulintheKsystem

∑

→ → Γ − Γ =         − +       + Γ − Γ Γ + Γ

f S L L S sw L S L S

f K A f K A i i ) ( ) ( 1 Im 1 Re tan

* 2

δ ε ε φ

Experimentalinput:KS,KL lifetimesand masses,decayamplitudesandCPV asymmetries WithKLOE(2006)input: Re(ε)=(160.2± 1.3)⋅10–5 Im(δ)=(1.2± 1.9)⋅10–5

CPV CPTV

TAM07 CP/T violation with K M. S. Sozzi

ε ε ε ε confrontstheSM

ε measuredto0.5% WaitingforlatticeQCD forKtobecomealso aquantitative testofSM. ε ≠ 0 constrains(poorly)theapexoftheUnitarity Triangle duetothetheoreticaldifficultyinhandlingthe hadronic uncertainties

TAM07 CP/T violation with K M. S. Sozzi

ConcerninglatticeQCD…

Quenchedapproximation(seaquarks ignored)isnowathingofthepast Itwouldappearthataccuracyreachedthe few%figure WearetolderrorsonCKMconstraints shouldhalveinthenexttwoyears (A.D.2007) Lattice2007: BK =0.557± 12± 29± 28± ? (boxdiagram~fK

2 BK

ε’/ε notforgotten(butmuchharder)

TAM07 CP/T violation with K M. S. Sozzi

KTeV (2006):112Kevents (40%oftotal) DE/(IB+DE)=0.689± 0.021 forEγ >20MeV NA48/2:220Kevents(20%oftotal) DE=(3.35± 0.43)%INT=(2.67± 1.09)% for0<T*π <80MeV INTcouldgive(direct)CPVO(10"4)

K→ ππγ

Directemission(DE) Innerbremsstrahlung (IB)

KL → π+π−γ

Separationbyphotonspectrum

K± → π+π0γ

TAM07 CP/T violation with K M. S. Sozzi

KL→ π+π−γ

FNALE731(1995): 8Keventsfitted afterregenerator |η+−γ|=(2.359± 0.062)W10−3 φ+−γ =(43.8± 3.5)° Fullyconsistentwithη+−: |ε’+−γ|/|ε| <0.3(90%CL)

• )

( ) , ( γ π π γ π π η

γ − + − + − +

→ − → =

S L

K A violating CP K A

KS"KL CPVinterferencelargelyfrom interferenceofthetwoE1IB: inthiscaseη+−γ =η+− AnE1DEcomponent(CPV)forKL couldinterferewith(CPC)E1IB andmodifyη+−γ (directCPV)

TAM07 CP/T violation with K M. S. Sozzi

KL → π+π−e+e− andCPV

Raredecayfirstobserved byKTeV andNA48: BR=(3.08± 0.20)⋅ 10−7 Internalγ conversion allowsspinanalysisof radiative KL → π+π−γ Theleptonplane

• rientation iscorrelated

tothephotonhelicity

• CPVinnerbremsstrahlung

CPCdirectemission CPVdirectemission Chargeradius

TAM07 CP/T violation with K M. S. Sozzi

AΦ = (0.5 ± 4.3) %

KL,S → π+π−e+e− andCPV

AΦ = (13.8 ± 2.2) %

(KTeV +NA48) NA48:Noasymmetry forKS (asexpected)

• Asymmetryinangleφ between

ππ andee planes,inagreement withtheory(indirectCPV)

φ φ φ φ φ cos sin sin cos

3 2 2 2 1

Γ + Γ + Γ = Γ d d

TAM07 CP/T violation with K M. S. Sozzi

KL,S → e+e−e+e− andCPV

ßCP ="0.23± 0.09± 0.02 γCP ="0.09± 0.09± 0.02 (KTeV)

ßCP ="0.25andγCP =0 fornoCPVandCP="1(K2)

• Asymmetryinangleφ between

thetwoee planes

φ γ φ β φ 2 sin 2 cos 1

CP CP

d d + + = Γ

TAM07 CP/T violation with K M. S. Sozzi

CPviolationinchargedKπ3

Nointrinsic∆I=1/2amplitude suppression(asforε’/ε)

• AnyCPVinchargedkaons isof

thedirect type

• Mostcopiousdecaymodes

possiblysupportingCPV: Largestatistics,simple selection,lowbackgrounds

• Hadronic uncertainties

Smallrescattering phases → SmallasymmetryinSM

2π (ε’/ε): 3π (Ag):

BR(K±→π±π+π−)=5.57% “charged” BR(K±→π±π0π0)=1.73% “neutral”

Widthasymmetriessuppressed:compareDalitz plotshapes (noabsoluteKfluxmeasurement)

TAM07 CP/T violation with K M. S. Sozzi

NA48/2(2003"2004) SearchforCPVinKπ3

Ag =(g+−g−)/(g++g−)≠ 0?

K− K+

≠

NA48/2exploitsmaximalcancellations(robustness)

• Simultaneous K+ andK− beams,superimposed inspace,with

narrow momentum spectra

• Detect asymmetry only from slopes of ratios ofnormalized u

distributions

• Equalize averaged K+ andK– acceptances byfrequently

alternatingpolaritiesofrelevantmagnets

Kinematics: si = (PK−Pπ

π π πi)2

i=1,2,3 (3=odd π) s0 = (s1+s2+s3)/3 u = (s3−s0)/mπ

2 = 2mK (mK/3−E*odd)/mπ 2

v = (s2−s1)/mπ

2 = 2mK(E*1−E*2)/mπ 2

Matrix element:

?

TAM07 CP/T violation with K M. S. Sozzi

NA48/2beams

PK spectra, 60± ± ± ±3 GeV/c 54 60 66 1cm 50 100 10 cm 200 250 m He tank + spectrometer

• Momentum

selection

• Focusing
• µ sweeping
• Cleaning
• Beam

spectrometer (0.7%)

~1⋅ ⋅ ⋅ ⋅1012 ppp

K+ K−

• focusing beams

BM

z

magnet

vacuum tank

nottoscale

K+ K−

− − −

2 ÷ 3 M K/spill (π/K ~ 12) π decay products stay in pipe 0º prod. angle

TAM07 CP/T violation with K M. S. Sozzi

u

• 1.5
• 1
• 0.5

0.5 1 1.5 |v| 0.5 1 1.5 2 2.5

Data"taking2003"04: 3.1x109 eventsselected(K+/K− ≈ 1.8) Nosignificantbackground Asymmetryanalysisusesmagnetic spectrometeronly

• NA48/2:K± → π±π+π–
• Slopeg≈ "22%

(alsore"measured byNA48/2)

TAM07 CP/T violation with K M. S. Sozzi

0.5 1 1.5 2 2.5 3

• 1.5
• 1
• 0.5

0.5 1 1.5

Data"taking2003"04: 9.1x107 eventsselected(K+/K− ≈ 1.8) Nosignificantbackground AsymmetryanalysisusesEM calorimeteronly

• NA48/2:K± → π±π0π0

Slopeg≈ 65% Largerslope(x3)

• ver"compensates

formuchsmaller statistics(1/30)

!

TAM07 CP/T violation with K M. S. Sozzi

NA48/2:detector asymmetry cancellation

N(A+B+K+) N(A+B-K-)

• Detectorleft"rightasymmetrycancels

in4ratiosofK+ overK− udistributions:

" " # # $ $

• Beam line: K+ Up

Beam line: K− Down

% − Indeces correspondto " beamline polarity(U/D) " directionofkaon deviation inspectrometer(S/J)

(same deviation by spectrometer in numerator and denominator)

N(A+B-K+) N(A+B+K-)

• N(A-B+K+)

N(A-B-K-)

• N(A-B-K+)

N(A-B+K-)

• Spectrometer

field K+ K−

Reverseeachday Reverseeachweek

TAM07 CP/T violation with K M. S. Sozzi

Morecancellations

∆

!" !" #$ %%& #$ %%&

Fit with quadruple ratio:

'% "(" ((( " ) ) "" " " " % %" %"* * "()" ( "()" ( %+# "&$ " ( " *(&%(,(#

N(A+B+K+) N(A+B-K-)

R=

N(A+B-K+) N(A+B+K-) N(A-B+K+) N(A-B-K-) N(A-B-K+) N(A-B+K-)

Cancel global time instabilities Cancel beam differences

TAM07 CP/T violation with K M. S. Sozzi

NA48/2:CPVinKπ3

(3.1W109 decays) (91W106 decays) Statisticsdominated.x10improvement.NoCPVfound. Finalresultsonfullstatistics(2003+2004) Ag(C) =("1.5± 1.5stat± 0.9trig± 1.1syst)⋅10–4 =("1.5± 2.1)⋅10–4 Ag(N) =(1.8± 1.7stat± 0.5syst)⋅10–4 =(1.8± 1.8)⋅10–4

arXiv:0707.0697,subm.toEPJC

TAM07 CP/T violation with K M. S. Sozzi

K± asymmetriesconfronttheSM

10-6

NA48/2

10-5 10-4 10-3 10-2

• .

. #)( &( #)( &(

HyperCP prelim. (2000) (“charged”) TNF (2004) (“neutral”) Ford et al. (1970) (“charged”) Smith et al. (1975) (“neutral”)

|Ag|

• Ag ~10−5 compatiblewithSM
• Ag >1W10−4 SUSY/NewPhysics

THEORY: SMcontribution:many theoreticalcomputations Largeuncertainties (~1orderofmagnitude) Enhancementspossible beyondSM C N E.Gámiz etal(2003) SMestimate(NLOChPT): Ag(C)=(–1.4±1.2±?)⋅10–5 Ag(N)=(1.1±0.7±?)⋅10–5

NPwindow“closed”,partofSUSYmodel parameterspaceexcluded

TAM07 CP/T violation with K M. S. Sozzi

Stimulatedmuchtheoreticalwork: Cabibbo etal.,Gamiz etal.,Colangelo etal. “Athresholdcusp” (Wigner 1948) Unperturbed matrixelement:

2

2 1 2 1 1 u h u g M ′ + + =

Finalstatepion scatteringeffect:

M(π0π0)

2M(π±)

NA48/2byproducts:ππ scattering

TAM07 CP/T violation with K M. S. Sozzi

NA48/2:ππ scattering

60Mevents(65%oftotal)

(a0–a2)m+ =0.261± 0.006stat ± 0.003syst ± 0.0013ext a2m+=–0.037± 0.013stat ± 0.009syst ± 0.0018ext (a0–a2)m+=0.263± 0.003stat ± 0.0014syst ± 0.0013ext UsingChPtconstraints[Colangelo etal.(2001)]:

Preliminary AsremarkedbyCabibbo(2004)thiseffectispotentiallythebest measurementofafundamentalobservableofQCD(pionscattering lengths),alsomeasuredbyothermeans(withandwithoutKaons) Also:evidenceforpionium bound stateformationO(10"5)ofK→3π Theoreticalworkneededtofullyexploit theprecisionoftheexperimentaldata

TAM07 CP/T violation with K M. S. Sozzi

• IfCPTisvalid(δ=0):

φππ ≈ atan(2∆m/ΓS)≈ 44°

• IfTisvalid(ε=0):

φππ ≈ atan(2∆m/ΓS)+π/2 ImprovedmeasurementsbyKTeV Experiment:φ+" =(43.4± 0.7)° φ00 =(43.7± 0.8)°

CPTis(largely)OK! Strong(indirect)indicationoftimereversalviolation

CPviolation: TorCPTfailure?

TAM07 CP/T violation with K M. S. Sozzi

Let’sthenspeakabout

TAM07 CP/T violation with K M. S. Sozzi

Tviolation:Kabir’s Test

) ( ) ( ) ( ) ( K K P K K P K K P K K P AT → + → → − → = DirectcomparisonofT"conjugate(virtual)transitions: CPLEAR(1998): 〈AT〉 =(6.6± 1.3)W 10"3 Usingsemi"leptonic decaysandassumingCPTindecays

[ ]

) cos( ) 2 / cosh( ) sin( ) Im( ) cos( ) Re( 2 ) Re( 4 ) (

2 /

mt t mt x mt e x t A

t T

∆ − ∆Γ ∆ + ∆ − + =

+ ∆Γ − −

ε

Fullyconsistentwithindirect CPVinK0 mixing

TAM07 CP/T violation with K M. S. Sozzi

T"oddcorrelations

Lookedforin3"bodydecays(w.spin)or4"bodydecays(momenta) BewareoffakeasymmetriesbyFinalStateInteractions Ke4 (K→ππeν)BR≈ 4W10−5 orKe3γ (K→πeνγ)BR≈ 3W10−4 Ke3γ:FSI:Aξ ≈ (0.5"1)W10−4 intheSM NPmodels:Aξ ≈ few10−4

( )

γ µ π γ µ π

ξ p p p p p p × ⋅ × =

) ( ) ( ) ( ) ( < + > < − > = ξ ξ ξ ξ

ξ

N N N N A

TAM07 CP/T violation with K M. S. Sozzi

Kℓ3γ T"oddcorrelations

ISTRA+(2005):Aξ =0.015± 0.021 (1400events) NA48/2:>104 eventsandcancellation

• fFSIeffectsbyK+/K− comparison

ISTRA+(2006):BR(K– →π05–νγ)≈ 9W10−5 Aξ ="0.03± 0.13 (400events) K3γ:FSI:Aξ ≈ 1.1W10−4 intheSM NPmodels:Aξ ≈ 2.5W10−4

• ISTRA+(Protvino)

TAM07 CP/T violation with K M. S. Sozzi

PT(5)inK53decays

AnotherT"oddcorrelationisthe PT(µ)orthogonaltodecayplaneinK3(3"body)decays Experimentsinthe’70sonKL">π"5+ν reachedtheFSIlimit:

(ξ beingtheratioofthetwoformfactorscontributing)

• (

)

µ µ π µ µ π

µ S p p S p p × ⋅ × = ) (

T

P

Im ξ =("7± 26)× 10"3

TAM07 CP/T violation with K M. S. Sozzi

T" violationsearch:KEKE246

660MeV/c K+ stoppedin activefibre target. Finalresult (8.3Mπ0µ+ν decays,1996"2000): PT(µ)=("1.7± 2.3± 1.1)× 10"3 Also105 µ+νγ decays (largerbackground,differentsensitivitytoNewPhysics). Plansforimprovedexperiment(x10)atJ"PARC. ChargedK3(3"body)decays TinyFSI(EM)inSM:sensitivetoNewPhysics Im ξ =("5.3± 7.1± 3.6)× 10"3

TAM07 CP/T violation with K M. S. Sozzi

Whatmorewithkaons ?

TAM07 CP/T violation with K M. S. Sozzi

K→

→ → → π π π πℓℓ decays

Switchtoquantitative testoftheSM Flavour sector,probingextremelyhighenergy scales:precisionfrontiercomplementary toLHCenergyfrontier Some(tiny!)BRs canbecomputedto veryhigh (fewpercent)precision

CPVdir “Nothingtonothing” <2.1W10"7 (KEKE391a) 2.8W10"11 (at2%)

KL → → → → π π π π0νν νν νν νν

Dedicatedexpt. 3evt.(bkg.0.45) 1.47+1.30

–0.89 W 10"10

(BNLE787+E949) 8W10"11 (at7%)

K+ → → → → π π π π+νν νν νν νν

CPC+CPV 2ev.(0.87bkg) <3.8W10"10 (FNALKTeV) 10"11 (CPVdir 1W10"12)

KL → → → → π π π π0J+J−

− − −

CPC+CPV 3ev.(2.05bkg) <2.8W10"10 (FNALKTeV) 10"11 (CPVdir 3W10"12)

KL → → → → π π π π0e+e−

− − −

TAM07 CP/T violation with K M. S. Sozzi

100 events Mean=SM 100 events Mean=E787/949

Today

?

E787/E949:BR(K+ → π+νν )=1.47+1.30

"0.89× 10"10

?

Whichistheissue?

Tomorrow Aprocesswith verysmall parametric uncertaintyin SMisrequired

TAM07 CP/T violation with K M. S. Sozzi

Complexsituation:3contributions(CPC,indirectCPV,directCPV) Ancillarymeasurements(NA48/1)onKSallowedtoconcludethat indirectCPVdominates

KL → → → → π π π π0ℓ+ℓ=

BR(KL → π0e+e")CPV× 1012 ≈ 17(ind)± 9(interf)+4(dir) BR(KL → π05+5")CPV × 1012 ≈ 8(ind)± 3(interf)+2(dir) SensitivitytodirectCPVpartretainedthroughinterference (dependingonsign– theorypredictspositive) No(alive)dedicatedexperimentsplanned

TAM07 CP/T violation with K M. S. Sozzi

( )

11 2 2 4 10

10 ) 1 . 1 . 8 ( ) ( 10 . 1 ) (

− − + +

× ± = − + × ≈ → ρ ρ η νν π A K B

K→ π

π π πνν intheSM

Z(γ)penguinandboxdiagrams Topintheloop,sensitivetoVtd Smalltheoreticaluncertainty Verychallengingexperimentally

W W s ν ν ν ν i d ν ν ν ν

Vis V*

id

e,µ µ µ µ,τ τ τ τ

i=u,c,t ν ν ν ν ν ν ν ν W Z

Vis V*

id

d s i

11 2 5 * 10

10 ) 4 . 8 . 2 ( ) ( ) Im( 10 2 . 2 ) (

− −

× ± =         × = →

t td ts L

x X V V K B λ νν π

CP"violating

TAM07 CP/T violation with K M. S. Sozzi

KL→π0νν at KEK:E391a

Threerunssince2004 From1weekdata:BR<2.1x10"7 (90%C.L.) FutureexperimentatJ"PARC,goalO(100)events

TAM07 CP/T violation with K M. S. Sozzi

• π

π π π

Atpresentstrenghtening thecollaboration Decayinflight(75GeV/c unseparated K+ beam) ReuseafewpartsoftheNA48apparatus Backgroundrejection: – K+ trackingin1GHz – PID(pi/mu)byRICH – γ vetoing(highEpion, lowineff.) – Kinematics Expect80SMevents in2years(2011+)

K+→π+νν atCERN:NA62

TAM07 CP/T violation with K M. S. Sozzi

Conclusions

The“newkidintown” (Bmesons)rightfully tookthesceneofflavour physicsandCP violationinthelast5years. However:

4thingsIamsureabout

(andIhopeIhaveconvincedyoutoo…)

TAM07 CP/T violation with K M. S. Sozzi

• AsthePhoenix,everytime

AsthePhoenix,everytimekaons kaons appearto appearto haveexhaustedtheirpotentialasasource haveexhaustedtheirpotentialasasource

• finformationonNature,
• finformationonNature,

theykeepprovidingsomethingnew theykeepprovidingsomethingnew

(e.g.testsofQCD,probesofhighscales) (e.g.testsofQCD,probesofhighscales)

Conclusions

TAM07 CP/T violation with K M. S. Sozzi

• The

Theprecisionfrontier precisionfrontier iscomplementarytothe iscomplementarytotheenergy energy frontier frontier insearchingforNewPhysics, insearchingforNewPhysics, andtheonlysourceofinformationonthe andtheonlysourceofinformationonthe flavour flavour couplingofanynewparticles couplingofanynewparticles Conclusions

TAM07 CP/T violation with K M. S. Sozzi

• Kaons

Kaons willkeepbeingused willkeepbeingused byalivelycommunityasatool byalivelycommunityasatool tofurtherunderstandthebasic tofurtherunderstandthebasic structureofmatter structureofmatter Conclusions