Dominant K L Branching Ratios, K L Lifetime and V us at KLOE
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Transcript of Dominant K L Branching Ratios, K L Lifetime and V us at KLOE
DPG - Dortmund 31.03.2006 1
Dominant Dominant KKL L Branching Ratios,Branching Ratios,
KKL L Lifetime and Lifetime and VVus us at KLOEat KLOE
Introduction - CKM and Vus
- DANE and KLOE KL physics - Branching Ratios - Lifetime - Form Factor - Vus f+(0) Conclusions
Paolo BeltrameIEKP University of Karlsruhe
DPG - Dortmund 31.03.2006 2
CKMCKM Matrix and Matrix and VVusus
95% 5% 0.00001%
VubVusVud
1)1(
2/1
)(2/1
23
22
32
AiA
A
iA
VVV
VVV
VVV
tbtstd
cbcscd
ubusud
Couplings parameters between quarks in Weak Interactions, mixing Mass and Weak Eigenstates. Wolfenstein parametrization: four free parameters (, A, , ). Standard Model does not predict the value of any of them.
CKM matrix unitarity: first row |Vud|2 + |Vus|2 + |Vub|2 ~ |Vud|2 + |Vus|2 1 –
Determination of Vus
K0 e,Kl3)semileptonic decays
)1()()0(192
22
3
52
3 EMIKl
usEWK
Kl IfVSMG
F
)1()()0(
192
22
3
52
3 EMIKl
usEWK
Kl IfVSMG
F
•
K0s +u
ve
eVus•
dd
DPG - Dortmund 31.03.2006 3
TheThe– Factory– Factory
(1020) – Factory: electron-positron-collider at s = M= 1019.4 MeV
BR( K+K) = 49.1%BR( KSKL) = 34.1%
– Factory K – Factory
KS
K+
KL
K-
The decay at rest provides monochromatic and pure beams of kaons
Tagging: observation of KL(KS) signals presence of KS(KL)-precision measurements of absolute BR’s
KL and KS are well separated: - c (KS) = 6 mm, KS decays near to the interaction point
- c (KL) = 3.4 m, large detector to keep reasonable acceptance for KL decays
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The DAThe DANENE– Factory– Factorys = M= 1019.4 MeVLdesign = 5 1032 cm-2 s-1 2004 750 pb-1
2005 1250 pb-1
2001 170 pb-1
2002 280 pb-1
Analysis nearly complete
Data taking at peak finished in 2005 Lpeak= 1.3 × 1032 cms
Ltot 2.4 fb-1
Off-peak run s = 1 GeV finished in March Ltot 250 pb-1
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The KLOE detectorThe KLOE detector
Magnetic Field of 0.52 T
Superconducting coil Superconducting coil
Track momentum resolutionp/p 0.4% ( > 45°)Vertex resolutionxy 150 m, z 2 mm
Drift chamber Drift chamber
12582 sense wires52140 wires in total90% He + 10% C4H10
Energy resolution E/E = 5.7%/E(GeV)Time resolution T = 54 ps/E(GeV) 50 ps
Electromagnetic calorimeter
Electromagnetic calorimeter
Lead/Scint fibres 4880 PM
DPG - Dortmund 31.03.2006 6
The Tagging methodThe Tagging method
KKSS
KKLL 2 2
KL tagged by KS vertex at IPEfficiency ~70% (mainly geometrical)KL angular resolution: ~1°KL momentum resolution: ~2 MeV
Tagging of KS, KL and K beams allows absolute Branching Ratios measurement:
TBFVseltag
sig α)(
1
N
NBR
LKTB
FVseltag
sig α)(
1
N
NBR
LK
Relies on capability of selecting a tagging kaon independently on the decay mode of the other kaon in the other hemisphere
In fact some dependence on signal mode exists: tag bias TB
Tag bias: carefully measured using MC, and data control samples, typically O(1%)
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Dominant Dominant KKLL Branching Ratios Branching RatiosHigh momentum resolution of KLOE DC Ke3, Kµ3, vertex
Tag KL by decay KS Charged decays selected by closing the kinematics at the vertex:
lesser of Pmiss- Emiss
Fit data with linear combination of three MC shapes Radiative corrections included in MC
2001-2002 Data: 328 pb-1 From PDG‘04 Rare KL decays: 0.0036 KL Lifetime: 51.50 nsBR(e+ + + 3KLOE
+ BR(+ ) PDG’04 = 1.0104 0.0076
Imposing (BR x) = 1
KL= (50.72 0.14stat0.36systns
(PmissEmiss) in or hyp
Data
e
(MeV)
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BR(KLe) = 0.4007 0.0006stat 0.0014syst
BR(KL) = 0.2698 0.0006stat 0.0014syst
BR(KL 3) = 0.1997 0.0005stat 0.0019syst
BR(KL) = 0.1263 0.0005stat
0.0011syst
Dominant KL Branching Ratios results (328 pb-1)
Reasonable agreement with KTeV and NA48 The new results go in the same direction respect to the PDG older values
Phys. Lett. B632 (2006) 43
DPG - Dortmund 31.03.2006 9
KKLL Lifetime: direct measurement Lifetime: direct measurement
+
clcl t,x
I.P. 0
L L
LK
Measure the meandecay path
L/c (ns)
6 - 24.8 ns40-165 cm
0.37 L
× 102 Events/0.3 nsPK = 110 MeVExcellent lever
arm for lifetime measurement
KL tagged by KS L and LK obtained from tcl At least three ’s required (LK) ~99% uniform in L 1.3% residual background L(KL) ~2 cm
Average with result from KL BR’s:L
= (50.840.23) ns
Time resolution of KLOE EmC KL
Phys. Lett. B626 (2005) 15
L= (50.920.17stat 0.17syst) ns
DPG - Dortmund 31.03.2006 10
KKe3e3 Form Factor slopes Form Factor slopes
Parametrizations:f(t) = f(0) [1 t]
or f(0) [1 t t2 / 2]
t = (pK - p)2 / m2+
Signal selection: - KLedecays tagged by KS
- Two tracks in fiducial volume forming vertex - Kinematic cuts + ToF PID to reduce background
Fit t distribution + 103
10-3
KTeVISTRA
NA48
KLOE
1 contours
20
10 ),(
j
FSRjjjiji FANN
Linear fit (2/dof ~ 330/363):
+ = (28.6 0.5 0.4) 10-3
Quadratic fit (2/dof ~ 325/362):
+ = (25.5 1.5 1.0) 10-3+ = (1.4 0.7 0.4) 10-3
hep-ex/0601038Submitted to Phys. Lett. B
DPG - Dortmund 31.03.2006 11
VVus us ff++(0) at KLOE(0) at KLOE
Quadratic Form Factor parametrization: KTeV + ISTRA+ = 0.0221 0.0011
+ 0.0023 0.0004
0 = 0.0154 0.0008
KL Lifetime: from KLOEAverage between KL BR’s and direct measurementL
= 50.84(23) ns
Kaon Semileptonic Branching Ratios: all of them from KLOEKLe3 KL3 KSe3 Ke3 K3
BR 0.4007 0.2698 0.00709 0.0505 0.0331
BR 0.0018 0.0012 0.00009 0.0004 0.0005
DPG - Dortmund 31.03.2006 12
ConclusionsConclusions
KLOE can determine the absolute KL Branching Ratios tagging the KL pure beam by means of KS →decaying in the other detector hemisphere
Using 328 pb-1 of 2001 and 2002 data, KLOE has measured the main KL Branching Ratios with relative errors of 0.5% - 1%
Using 400 pb-1 of data collected in 2001 and 2002 , ~106 KL → events, KLOE has performed a direct measurement of KL Lifetime at the level of 0.5%
KLOE has measured the K – vector current parameters using 328 pb-1 of data collected in 2001 and 2002, corresponding to ~2106 of KL →e events
Using Form Factor parameters from KTeV and ISTRA, KL Lifetime determined by KLOE (average between direct and KL BR’s measurements), main KL Branching Ratios (KLe3, KL3, KSe3, K e3, K3): KLOE has extracted Vus f+(0) value with a relative error, on the average, of 0.2%
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The Ademollo Gatto theoremAdemollo Gatto theorem: “for strangeness-violating leptonic decays of baryons and mesons: the vector coupling constants (i.e., the limit of the vector amplitudes for vanishing momentum transfer) are uniquely predicted up to first order in symmetry breaking.”
More theoryMore theory
Electromagnetic correction
Virtual corrections Real Bremsstrahlung changes (in addition) significantly the accpetance
Acceptance
100%KLOE MC
%1.0/ radcor
usus VV
DPG - Dortmund 31.03.2006 15
KKLL physics at KLOE: determination of physics at KLOE: determination of VVusus
)1()()0(192
22
3
52
3 EMIKli
usEWK
Kl IfVSMG
F
)1()()0(
192
22
3
52
3 EMIKli
usEWK
Kl IfVSMG
F
Kl3 Partial Decay width – Experiment
Kl3 = BR(KL→l)/KL
SEW Short ElectroWeak Radiative corrections – Theory
Included in Monte CarloEM Electromagnetic corrections and SU(2) corrections – Theory
Included in Monte Carlof+(0) Form Factor at t=0 – Theory
f+(0) theoretical calculationsIKl() Integral over the momentum dependence of the Form Factor – Experiment
IKl() determined by KLOE and other experiments
)0(
)0( 2/1
)(
)( 2/1
2/1
BR 2/1 0
0
K
K
us
us
f
f
I
I
BRV
V
0.5% 0.4% 0.4%
experimental
0.8%
theoretical
DPG - Dortmund 31.03.2006 16
Form Factor parameterizationsForm Factor parameterizations
20,0,0, /1)0()( Mttftf
42''2' 2//1)0()( MtMttftf
200 /1)0()( Mttftf
20,
0, /1
)0()(
Mt
tftf
Linear
Quadratic
Pole
20
10 ),(
j
FSRjjjiji FANN
Fit on t spectrum
Aij Smearing matrix (MC)j Reconstruction efficiencyj “Bare” Ke3 decay densityFj
FSR FSR correction
KTeV
Ke3
- phase space
Ed B
lucher
t
dN/d
tphase space + FF
DPG - Dortmund 31.03.2006 18
VVus us compared with unitarity and compared with unitarity and VVudud
The value considered for Vud is 0.9740 0.0005 taken from A. Czarnecki, W. J. Marciano, A. Sirlin, Phys. Rev. D70 (2004) 093006
Unitarity Band(1-|Vud|2)·f+(0)
Leutwyler-Roos FFconf. by LatticeNew Vud value
from 0+ 0+
0.9738 ±0.0003
Unitarity Band(1-|Vud|2)·f+(0)
Bijnens-Talavera FF New Vud value
from 0+0+
0.9738 ±0.0003
|Vu
s|
f +K
π(0
)
PDG02 PDG02
DPG - Dortmund 31.03.2006 19
PTPT Leutwyler-Roos (1984) f+(0) = 0.961 0.008 PT + Quark Model (Bijnens-Talavera, 2003) f+(0) = 1 + fp4 + fp6
loop + fp6LR = 0.976 ± 0.010
PT + Dispersion Relations (Jamin-Oller-Pich, 2004) f+(0) = 0.974 0.011 PT + Large NC (Cirigliano-Eidemuller-Kaiser-Pich-Portoles, 2005) f+(0) = 0.984 0.012
Lattice-QCDLattice-QCD (Becirevic-Isidori-Lubicz-Martinelli-Simula-Tarantino-Villadoro)
f+(0) = 1 + fp4+ fp6q = 0.960 ± 0.005stat ± 0.007syst
Kaon Form Factor at zero momentum transferredKaon Form Factor at zero momentum transferred
DPG - Dortmund 31.03.2006 20
Perspectives with 2.5 fb of collected data:• Limit on KS 000 at 10 –8 level
• Competitive measurement of KS +-0
• Ks semileptonic asymmetry to 4 10-3
• Fractional accuracy of < 1% on the BR for KS e and for Kℓ3
• Form factors of KL and K semileptonic decays
• First direct measurement of BR(KS ), accuracy < 2%
• Studies of KSKL system with interference: exploit KLOE’s capability to
CP,CPT mmts
FutureFuture