Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Latest results on kaon physics
Vus
KS rare and “semi” rare decays
CP violation in charged kaonscattering lengthFuture programsOutlook & Conclusions
In spite of a long history the K system is still a laboratory for interesting physics: flavour physics, CP violation. It can be a sensitive probe for NP. Most of the recent results come from KLOE, KTEV, NA48
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Unitarity test of CKM: Vus Saga
|Vud|2 + |Vus|2 + |Vub|2 = 1
Unitarity (or lack thereof) of CKM matrix tests existence of further quark generations and possible new physics (eg. Supersymmetry)
Vud2 = 0.9482±0.0010 (nuclear decays)
Vus2 = 0.0484±0.0011 ( from e.g. K+0e+e )
Vub2 = 0.000011±0.000003 ( B meson decays)
Most precise test of unitarity possible at present comes from 1st row:
2|Vud|dVud = 0.0010
2|Vus|dVus = 0.0011 PDG
2004|Vud|2 + |Vus|2 + |Vub|2 = 0 9972±0.0015 (~ 2 deviation)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Vus from Kl3 decays
• I() phase space integral, Sew short distance corrections (1.0232)
|Vus| is extracted from Kl3 partial decay widths
where i runs over the four modes K±,0(e3), K±,0(3)
G2M5
Ki • Ni = C2
i [Ci=1(2-½) for neutral (charged kaon decays)] 1923
Ii () ) phase space electromagnetic correction
• f+K0-(0) form factor at zero momentum transfer: pure theory calculation (PT, lattice)
i SU(2) ,e2p2 form factor correction due to isospin breaking (strong and electromagnetic)
few 10-2
slopes (momentum dependence of the vector and scalar form factors)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Unitarity test of CKM: Vus Saga
2003: First hint: BNL E865
Br(K+→π0e+ν) =(5.13±0.02stat±0.10sys)% PDG(<2004): (4.87±0.06)%
Vus consistent with unitarity but 2.7σ above existing Br(K ± →π0e±ν) value.
Key issue is systematic control of the Branching Ratio.Detector not optimized for photons (designed for π+μ-e+)Require: π0 e+e-γ in signal and normalization ( K+→+π0)
2004: KLOE KTEV, NA48 experiments measure Kl3 branching ratio for Ks and KL , lifetime and form factors with different techniques
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KKLL “crash”“crash”= 0.22 (TOF)= 0.22 (TOF)
KKSS ee
KS tagged by KL interaction in EmCEfficiency ~ 30%KS momentum resolution ~ 1 MeV
KKSS
KKLL 2 2
KL tagged by KS+-
Efficiency ~ 70%KL momentum resolution ~ 1 MeV
KLOE:Tagging of neutral kaons
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE:Measurement of KL BR’s
)(/)()()(
1
N
N i)BR(K
tag
iL allii tagtagLFVrec
Reconstruction efficiencies: KL , e (rec) 55% KL (rec) 40% KL (rec) 100%
Integral over the fiducial volume: ε (FV, L) 26%, depends on L
Tagging efficiency
Trigger required on the KS side
Tagging Precisely measure absolute branching ratios
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE:KL30
KS
At least 3 neutral clustersNeutral vertex reconstructed along KL direction using TofEfficiency close to 100%, bkg 1%
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE:KLcharged
KS
2 tracks forming a vertex along the KL direction.Vertex and tracking efficiency 55% for Kl3 and 40% for 3
P-E() (MeV)
Events counted by fitting missing momentum minus missing energy in the pion-muon hypothesis
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE: KLchargedPmiss - Emiss distribution very sensitive to radiation and momentum resolutionCheck data/MC agreement via independent PIDRadiative corrections properly included in the Monte Carlo generators (IR-finite treatment of radiative effects (no energy cutoff))
KL econtrol sample KL control sample
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE: Absolute BR's results
BR(KLe) = 0.4049 0.0010 0.0031 ~8105 events
BR(KL) = 0.2726 0.0008 0.0022 ~ 5105 events
BR(KL 3) = 0.2018 0.0004 0.0026 ~ 7105 events
BR(KL) = 0.1276 0.0006 0.0016 ~ 2105 events
• Absolute BR results with (KL
= 51.54 ns):
¾ of 2001-2002 data has been used for efficiency evaluation and
¼ for BR measurement corresponding to 13106 tagged KL.
330 pb-1
2001-2002
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE: BR results
KL
= 50.72 0.140.36ns
Assuming BR(KLX) =1
independent measurement of KL
BR(KLe) = 0.4007 0.0006 0.0014
BR(KL) = 0.2698 0.0006 0.0014
BR(KL 3) = 0.1997 0.0005 0.0019
BR(KL) = 0.1263 0.0005 0.0011
BR(e ++ +3 + rare decays from PDG) = 1.0104 0.0076
KL FV acceptance depends on the lifetime :
Systematics evaluated including
full error matrix from all sources.
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE: KL lifetime from KL30
• Large acceptance for KL decays 0.4 high statistical accuracy•KL momentum measured from KS+-
• KL30 efficiency >99% little variation along the KL path•KL+-0 as a control sample for the estimate of efficiency, resolution and time scale
PDG) (fit) = (51.7 PDG) (fit) = (51.7 ±± 0.4) ns 0.4) ns(Vosburg, 1972) =(Vosburg, 1972) =±±ns - 0.4 Mevents ns - 0.4 Mevents L(KLOE) = (50.87 ± 0.16 ± 0.26 ) ns - 14.5 Mevents – 440 pb-1
+ data
Eve
nts
/0.3
ns
t*= LK/c (ns)
6 -26 ns (40% L)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
NA48 & KTeV Measurements
BR(KLe
)BR(2 track)= 0.4978 0.0035
Using PDG-KTeV average for BR(KL 3)
BR(KLe) = 0.401
0.0045
Both experiments measures ratio of BR
They also have a preliminary measurement of BR(KL 3) = 0.19660.0035
BR(K e)=0.05140.0006
NA48 KTeV
KTeV measure 5 KL ratios
e3 / 3 , +-0/ e3 , 000/ e3
+- / e3 , 00 /
These 6 decay modes account for 99.93% of KL decays and the ratiocan be combined to extract BR
(~6 million reconstructed Ke3) (sample sizes 105-106)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
BR comparison
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Vus from Kl3 decays and L
hep-ph/0411097 (F. Mescia @ICHEP04)
1) Quadratic parametrization of the form factor momentum dependence:
from KTeV + ISTRA
2) KL lifetime from KLOE (average of the two measurements) :
KL
= (50.81
ns3) BRs from KLOE (setting the sum =1):
4) Form factor f+K(0) from Leutwyler-Roos: 0.961(8)
BR(KLe) = 0.4007 0.0006
0.0014
BR(KL) = 0.2698 0.0006
0.0014
2
2
2 21)0()(
m
t
m
tftf
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Vus from Kl3 decays and L
KLOE results: |Vus
|f+
K(0) (KSe3
) = 0.2169 0.0017
|Vus
|f+
K(0) (KLe3
) = 0.2164 0.0007 |V
us|f
+K(0)(K
L3) = 0.2174 0.0009
From Unitarity: (1-|Vud
|2)1/2f+
K(0) = 0.2177 0.0028
|Vus|f+Kπ(0)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE: BR(K++())
• Tag from K-- • 2002 data 175 pb-1 (2/3 is used as efficiency sample)• Background events identified by the presence of a neutral pion.
P()*(MeV)
Particle momentum in K rest frameCombining the experimental value of
(K())/(())with the ratio
fK/f obtained from lattice calculations
we can extract the ratio |Vus|/|Vud| (Marciano hep-ph/0406324)Selection
e
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KLOE: BR(K++())
P()*(MeV)
• Event counting performed by fitting the P* distribution with signal and background shapes obtained from data control samples: bkg-sample selected by looking for 2 photons from neutral pion; control sample for signal shape selected by identifying the muon cluster in the Emc. •Systematics are dominated by efficiency estimate.
BR(K+ + = 0.6366 ± 0.0009 (stat.) ± 0.0012 (syst.)
Chiang = 0.6324 PDG fit = 0.6343
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
• fK /f =1.210±0.014 (MILC Coll. hep-lat/0407028)
Following the method from Marciano hep-ph/0406324 :
Vus=0.2223±0.0025
• Vud=0.9740±0.0005 (superallowed -decays)
Vus from K++()
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
(MK0 MK0) (MK0 MK0)
SM prediction: S000
= L000|+000|2 BR(KS 30) = 1.9 x 109
Best limit from: direct search SND ’99 : BR(KS 30) < 1.4 x 105
interference NA48 ’05: BR(KS 30) < 7.4 x 107
Uncertainty on KS 30 amplitude limits precision of CPT test:
_ _
from unitarity
S,L = (1 + i tanSW)Re f A*(KSf) A(KLf)/S = (i + tanSW) Im
MK MK
2 10 8 10 MK/MPlanck = 4 10-20)
Observation of KS 30 signals CP violation in mixing and/or in decay:
A limit on BR(KS 30) at 107 level translates into a 2.5-fold improvement on the accuracy of Im , i.e.
KS 000 – test of CP and CPT
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Signal selection
•KS’s tagged by of Kcrash
•6 photons clusters, no tracks from IP
•Kinematic fit to improve cluster
parameter Background rejection
KS + 2 fake ’s •Signal box in plane
pairing of 6 clusters with better 0 mass estimates
pairing of 4’s out of 6: 0 masses, E(KS), P(KS), c.m. angle between 0’s
•Final cut on residual Ks energy: E(Ks )- E
DataMC 30 BR 10-5
0
20
40
80
60
4010 20 30
KLOE: : Search for KS 000
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KS 000 – Final Results
KLOE: 450 pb-1 ’01+’02 data
Nsel(data) = 2 events selected as signal
= 24.5%
Nsel(bkg) = 3.130.82stat0.37sys
bkg events expected from MC
N2BR(KS 000) = BR(KS 00) < 1.2 10-7,
N3
Normalize signal counts to KS 00 count in the same data set:
Can state: N3 < 3.45 with a 90% CL
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Using PDG value and our limit we obtain:
@ 90% CL
A(KS 000)
A(KL 000)
Accepted for publicationUL will decrease by ~ 10
•Increased statistics: x 6.5 improvement•Increased background rejection
2 fb-1 Prospect
|000| = < 1.8 10-2
NA48
KLOE
KLOE: : KS 000 – Final Results
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Sensitivity to CPT violating effects through charge asymmetry:
Sensitivity to CP violation in K0-K0 mixing:
AS = 2Re (CPT symmetry assumed)
_
AS never measured before
If CPT holds, AS=AL
ASAL signals CPT violation in mixing and/or decay with SQ
(KS,L -e+) (KS,L +e-)
(KS,L -e+) (KS,L +e-)
_
_AS,L =
Can extract |Vus| via measurement of BR(KS e)
Test of the S = Q rule, (KS e)/(KL e) = 1 + 4 Re(x)
KS e decays – Physics issues
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KS e decays: Results
•Further rejection of KS background from TOF identification
•Obtain number of signal events from a constrained likelihood fit to multiple data distributions
•Normalize to KS in the same data set
Use BR(KS ) to calculate BR(KS e)
• Kinematic closure: use KL to obtain KS momentum PK and test for presence of neutrino:
Emiss = MK2 + PK
2 – E– Ee
Pmiss = |PK – P– Pe |
Data
— MC sig + bkg
EmisscPmiss(MeV)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KS e decays: Results
Dependence of efficiencies on charge mainly due to TOF effects, estimated using data control sample of KL e
AS = (2 9stat 5syst) 10-3
BR(KS e+) = (3.54 0.06stat 0.04syst) 10-4
BR(KS e-) = (3.55 0.05stat 0.02syst) 10-4
AL = (3.322 0.058 0.047) 10-3 [KTeV 2002]
AL = (3.317 0.070 0.072) 10-3 [NA48 2003]
Published result: (6.91 0.34stat 0.15syst) 10-4, KLOE ’02
BR(KS e) = (7.09 0.08stat 0.05syst) 10-4
Uncertainty in charge asymmetry still dominated by statistics
With data for an integrated luminosity of 2.5 fb, AS 3 10Re
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
KS e decays: Results
Re(x) = (2.7 3.0stat 1.8syst) 10
Use BR(KL e±KTeV04]
Re(x) = (.1 3.2stat 1.8syst) 10
Use BR(KL e±KLOE05
Use average of KTeV and NA48 measurement of the KS lifetime: S = (89.62 0.05) ps
Use new measurement of the KL lifetime: L = (50.89 0.23) ns KLOE ’05
Compare (KS e) with (KL e): test of the S Q rule
4Re(x) = (KS e)/(KL e)1
KTeV04
KLOE05
PDG04
KLOE KS
Most precise measurement of Re(x) (in CPT conserving transitions): compare with CPLEAR99, Re(x) = 6 x 10
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Direct CP-violation in K3
• Matrix elementparameterized in terms of slopes
• Kinematics
• Measured quantity sensitive to direct CP violation:
Charged kaon: direct CP violation only
|M(u,v)|2 ~ 1 + gu + hu2 + kv2
Ag = (g+-g-)/(g+
+g-)≠0
u = (s3-s0)/m2 =2mK∙(mK/3-Eodd)/m
2;
v = (s2-s1)/m2= 2mK∙(E1-E2)/m
2
si = (PK-Pi)2, i=1,2,3 (3=odd );
s0 = (s1+s2+s3)/3.
BR(K±±+)=5.57%; BR(K±±00)=1.73%.
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
10-6
|Ag|
Experimental precisions by 2005:Experimental precisions by 2005:
10-5
10-4
10-3
10-2
SMSM SUSYSUSYNewNew
physicsphysics
Ford et al. (1970)
HyperCP prelim. (2000)
TNF prelim. (2002)“neutral” mode
NA48/2proposal
• SM estimates vary within an order of magnitude
(few 10-6… 8×10-5)
• Models beyond SM predict substantial enhancement partially within the reach of NA48/2
• Asymmetry in decay widths expected to be smaller than in Dalitz slopes
(SM: ~10-7… 10-6)
[[AAgg~10~10-3-3]]
“charged”“neutral”
Theory
Theoretical expectations
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
NA48/2 goals and methodM.S. Sozzi
• Primary NA48/2 goals:Primary NA48/2 goals:– Measure slope asymmetries in “charged” and “neutral”
modes with accuracies δAg<2.2∙10-4, and δAg0<3.5∙10-4,
respectively. Requires >2∙109 decays in “charged” mode and >108 in “neutral” mode.
• NA48/2 method:NA48/2 method:– Two simultaneous K+ and K– beams, superimposed in
space, with narrow momentum spectra;– Detect asymmetry exclusively considering slopes of ratios
of normalized U distributions. If acceptance is equal for K+ and K–, R(u) = N+(u)/N–(u) ≈
≈ n∙(1+g+u)/(1+g–u) ≈ ≈ n∙(1+2gu)
– Equalize K+ and K– acceptances by frequently alternating polarities of relevant magnets.
Δg = 2g∙Ag
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
M.S. Sozzi
|V|
Data-taking 2003: 1.61x101.61x1099 events selected
KK+ + : 1.03x10: 1.03x109 9 eventsevents
MM=1.7 MeV/c=1.7 MeV/c22
Events
M(3) GeV/c2
UAg = (0.5±2.4stat.±2.1stat.(trig.)±2.1syst.)x10-
4 = (0.5±3.8)x10-4
NA48/2:Selected statistics 2003
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Cusp-like effect in K++00
Interference generate a cusp in the spectrum next to threshold, not seen earlier by lower precision experiments
One loop calculation: cusp located at m = 2m+ N. Cabibbo hep-ph/0405001
Recent two loops calculation: d/(dm)2 F (a0 -a2 , a2 , g, h, m) allows to extract
scattering lengths a0 -a2 from m spectrum N. Cabibbo ,G. Isidori hep-ph/0502130
To be compared to precise (2%) PT prediction
M0 = 1+gu/2 M1 (a0 -a2)
d/dm |M0 + M1|2
Two diagram contribute: direct emission, re-scattering
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Cusp-like effect in K++00
Best fit obtained with 2 loops and a smallcontribution from pionium fixed to:BR(K pionium)/ BR(K3) 0.8 10-5
(a0 -a2)·m= 0.281 ± 0.007 (stat.) ±0.014 (syst.) ± 0.014 (theor.) NA48/2 prel
NA48/2 2x108 K++00
4x109 K++ –+2003-2004
50 days-2003
m2
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Rare Kaon decays mediated by Flavor Changing Neutral Currents are the main experimental tool to probe the flavour structure of physics beyond the SM independent from B mesons.
• No SM tree-level contribution
• Strong suppression within the SM because
of CKM hierarchy
• Predicted with high precision within the SM
if dominated by short-distance dynamics G. Isidori
(holy grail)
|Vtd|
* 2 5t
2
20
s
2
5
4
td
4
0 0 10
10
10
11
( ):
( ) 1.8 10 ( )
4.1 10 3.0
( ) 1.0 10
Standard Mode =I l
0.6 10
I mV Vm A
I
=
mB
B
t
t
tL
Buras
x X x
x A
x A
x
K
K
2 117.8 1.2 10x
Rare Kaon Decays and the SM
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Status & Future programs•K0
L –Upper limit is 4 order of magnitude from the SM prediction, KTEV@FNAL
–Expect results from data collected by E391a@KEK (proposed SES~3 10-
10)
–Next experiment KOPIO@ BNL (>100 signal events), JPARC (180 signal events)
•K+ –3 clean events are published (in agreement with SM)
–Next experiment: NA48/3@CERN (O(100 ) signal events), JPARC (> 50 signal events)
–Move from stopped to in flight experiments (increased acceptance)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Outlook & Conclusions
• In spite of a long history the K system is still a laboratory for interesting physics: flavour physics, CP violation etc..
• “Unitarity Crisis” in first row of CKM matrix seems resolved.
• In the next year we will have new results on KL and KS K decays from KLOE ( 2fb-1 will be collected by the end of 2005) and NA48.
• Many experiment proposed (not yet approoved) on rare kaon decays will probe the flavour structure of physics beyond the SM
Is kaon physics still interesting???
Answer is YES!!!
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
20 200 04060 40
Data— MC sig + bkg
60 80
Emiss–Pmiss(MeV)
BR(KS e) = (7.09 0.07stat 0.08syst) 10-4
KS semileptonic decay
•Selected using Tof technique•Event counting obtained by fitting the E(e)-P distribution•The two charge modes are measured independently• selected ~104 signal events per charge in the 2001-2002 data sample.
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
W = m
(1019.4 MeV)
Ldesign
51032 cm-2 s-1
DANE2002:270 pb-1
2001: 170 pb-1
2000: 20 pb-1
2004 best Lpeak 1.2×1032 cm-2s-1
2004 avg L ~6×1031cm-2s-1
Collected 770 pb-1 since May 2004
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Conclusion
•The dominant KL BR’s with 0.5% accuracy• The KL lifetime with 0.6% accuracy• BR(KS e) with 1% accuracy• BR(K+ +) with 0.2% accuracy • All BR’s are inclusive of the radiation
With the data collected in the year 2001-2002 KLOE has measured:
A large number of K semileptonic decays has been collected and identified
will allow us to measure all the BR’s with better than 1% accuracy
KLOE is now measuring:• K± lifetime• Kl3 form factor• KS BRComing soon the update of (KS+-())/(KS00) measurement We expect to collect 2fb-1 for the end of December 2005
Final papers are under review by the Collaboration
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Unitarity test of CKM: Vus Saga
EXP: Need to measure BR, lifetime, and slopes with good accuracy TH : Need to improve estimate on f(0)
0
0
30
1
20
1
2
1
BR
BR
2
1
0
0
f
f
V
V
us
us
exp th
0.3 % 0.4% 0.3% 0.8%K0 e0.6% 0.1% 0.3% 0.8%K e
0.5% 0.4% 0.8% 0.8%K0 0.6%
0.9% 0.1% 1.5% 0.8%K 0.2%
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
The KLOE detector
CalorimeterCalorimeter
(E)/E = 5.7%/E(GeV) (t) = 54 ps/E(GeV) 100 ps
p/p0.4 % (tracks with > 45°)x
hit150 m (xy), 2 mm (z)x
vertex ~ 1 mm(M) ~ 1 MeV
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Radiative corrections
IR-finite treatment of radiative effects in MC (no energy cutoff)The E-P shape is checked using Ke3/K3 enriched samples obtained from an independent calorimetric selection: Tof, E/p, and cluster centroid position.The Ke3 BR changes by 2% neglecting the radiative tail.
P-E() (MeV)P-E(e) (MeV)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Semileptonic decays of K±
Absolute BR measurement.
K±, decays used to tag the events. Kl3 selection: kaon decay vertex in FV Reject two-body decays: P*() 195
MeV Cut on missing momentum to reject decays.
0 search: 2 neutral clusters in EmC, prompt wrt the K vertex.
Spectrum of charged daughter mass, m2, from TOF measurement.
m2=p2 [(cT/L)2-1]
Ratio of data and MC efficiency is used to correct MC acceptance.
KK
KK
ee
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Semileptonic decays of K±
K++0 Tag
Tag K+2 Tag K+2 Tag K-2 Tag K-2
NKe3 67 022 331 26 774 215 71 188 345 25 942 211
NK3 42 096 282 16 586 179 44 925 293 16 465 180
ml2=pTRK
2 [(c(tl-t)/LTRK )2-1]
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Tagging of charged kaons
• Tag performed selecting K± ±, ±0 decays (85% of K±) by measuring the charged particle momentum in the K rest frame (P*).• In the following analyses the trigger is required on the tag side.
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Generators for radiative K decays
12
b
o M
EbA
dE
d
Motivation: acceptance evaluation with accuracy better than 1%, shape of kinematic variables (e.g. Emiss-pmiss spectrum)
New MC generators for and Kl3 decays including radiated photon, without any cutoff on the energy. The fraction of events in the tail is in agreement with present experimental knowledge:
2
2
2
1093.0
1093.0
10)015.0908.0(
)(
)2030,(
MC
aletBijnens
kTeV
eKBR
MeVEeKBR
L
eL
310)07.059.2()(
)50,(
S
S
KBR
MeVEKBR E731 (2.560.09)10-3
MC 2.6 10-3
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Vus from Kl3 decays and L
KLOE results: |Vus
|f+
K(0) (KSe3
) = 0.2169 0.0017
|Vus
|f+
K(0) (KLe3
) = 0.2164 0.0007 |V
us|f
+K(0)(K
L3) = 0.2174 0.0009
From Unitarity: (1-|Vud
|2)1/2f+
K(0) = 0.2181 0.0022 New Vud
|Vus|f+Kπ(0)
New Vud
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Vus from Kl3 decays and L
1-|Vud
|2)1/2f+
K(0) = 0.2181 0.0022
new vud=0.9739(3) old vud 0.9740(5) new vus 0.2269(13) old vus 0.2265(22)
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Kaons at KLOE
K+K- 1.5 106/pb-1
KLKS 106/pb-1
• The decays at rest allow us to select monochromatic (p ~ 110 MeV/c) pure beams of
Kaons • Observation of KL,S signals presence of KS,L
• KS decays near IP: S ~ 0.6 cm• ~50% of KL decays inside the detector: L ~ 340 cm• ± ~ 95 cm• Events per pb-1:
KS(+)
KL(-)
~4 m
Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005
Kaon Rare Decays and the SM(holy grail)
Kaons provide quantitative tests of SM independentfrom B mesons…
…and a large windowof opportunity exists!
G. Isidori
Im t = A2 5 Re t = A2 5
Vtd