1. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Latest results on kaon physics V us K S rare and “semi” rare decays CP violation in charged kaon  scattering length Future programs Outlook & 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

2. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Unitarity test of CKM: V us Saga |V ud | 2 + |V us | 2 + |V ub | 2 = 1 Unitarity (or lack thereof) of CKM matrix tests existence of further quark generations and possible new physics (eg. Supersymmetry) V ud 2 = 0.9482±0.0010 (nuclear decays) V us 2 = 0.0484±0.0011 ( from e.g. K +  0 e + e ) V ub 2 = 0.000011±0.000003 ( B meson decays) Most precise test of unitarity possible at present comes from 1 st row: 2|V ud |dV ud = 0.0010 2|V us |dV us = 0.0011 PDG 2004 |V ud | 2 + |V us | 2 + |V ub | 2 = 0 9972±0.0015 (~ 2  deviation)

3. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 V us from Kl3 decays I(      ) phase space integral, S ew short distance corrections (1.0232) |V us | is extracted from K l3 partial decay widths where i runs over the four modes K ±,0 (e3), K ±,0 (  3) G 2  M 5 Ki N i = C 2 i [Ci=1(2 -½ ) for neutral (charged kaon decays)] 192  3    I i (    ) ) 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)

4. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Unitarity test of CKM: V us Saga 2003: First hint: BNL E865 Br (K + →π 0 e + ν) =(5.13±0.02stat±0.10sys)% PDG(<2004): (4.87±0.06)% V us consistent with unitarity but 2.7σ above existing Br(K ± →π 0 e ± ν) value.  Key issue is systematic control of the Branching Ratio.  Detector not optimized for photons (designed for π + μ - e + )  Require: π 0  e + e - γ in signal and normalization ( K + →  + π 0 ) 2004: KLOE KTEV, NA48 experiments measure K l3 branching ratio for K s and K L, lifetime and form factors with different techniques

5. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 K L “crash”  = 0.22 (TOF) K S    e  K S    e  K S tagged by K L interaction in EmC Efficiency ~ 30% K S momentum resolution ~ 1 MeV KS  KS  KS  KS   KL  2KL  2KL  2KL  2 K L tagged by K S  +  - Efficiency ~ 70% K L momentum resolution ~ 1 MeV KLOE:Tagging of neutral kaons

6. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE:Measurement of K L BR’s Reconstruction efficiencies: K L ,  e  (rec)  55% K L         (rec)  40% K L     (rec)  100% Integral over the fiducial volume: ε (FV,  L )  26%, depends on  L Tagging efficiency Trigger required on the K S side Tagging  Precisely measure absolute branching ratios

7. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE:K L  3  0 K S     At least 3 neutral clusters Neutral vertex reconstructed along K L direction using Tof Efficiency close to 100%, bkg 1%

8. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE:K L  charged K S     2 tracks forming a vertex along the K L 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

9. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE: K L  charged P miss - E miss distribution very sensitive to radiation and momentum resolution Check data/MC agreement via independent PID Radiative corrections properly included in the Monte Carlo generators ( IR-finite treatment of radiative effects (no energy cutoff)) K L   e  control sample K L   control sample

10. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE: Absolute BR's results BR(K L  e ) = 0.4049  0.0010  0.0031 ~8  10 5 events BR(K L  ) = 0.2726  0.0008  0.0022 ~ 5  10 5 events BR(K L  3   ) = 0.2018  0.0004  0.0026 ~ 7  10 5 events BR(K L        ) = 0.1276  0.0006  0.0016 ~ 2  10 5 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 13  10 6 tagged K L. 330 pb -1 2001-2002

11. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE: BR results  KL = 50.72  0.14  0.36  ns Assuming  BR(K L  X) =1 independent measurement of  KL BR(K L  e ) = 0.4007  0.0006  0.0014 BR(K L  ) = 0.2698  0.0006  0.0014 BR(K L  3   ) = 0.1997  0.0005  0.0019 BR(K L        ) = 0.1263  0.0005  0.0011 BR(  e +  +       +3   + rare decays from PDG) = 1.0104  0.0076 K L FV acceptance depends on the lifetime : Systematics evaluated including full error matrix from all sources.

12. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 KLOE: K L lifetime from K L  3  0 Large acceptance for K L decays  0.4  high statistical accuracy K L momentum measured from K S  +  - K L  3  0 efficiency >99% little variation along the K L path K L  +  -  0 as a control sample for the estimate of efficiency, resolution and time scale  PDG) (fit) = (51.7 ± 0.4) ns  (Vosburg, 1972) =  ±  ns - 0.4 Mevents   L  (KLOE) = (50.87 ± 0.16 ± 0.26 ) ns - 14.5 Mevents – 440 pb -1 + data Events/0.3 ns t*= L K /  c (ns) 6 -26 ns (40%  L )

13. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 NA48 & KTeV Measurements BR(K L   e ) BR(2 track) = 0.4978  0.0035 Using PDG-KTeV average for BR (K L  3   ) BR(K L  e ) = 0.401  0.0045 Both experiments measures ratio of BR They also have a preliminary measurement of BR(K L  3   ) = 0.1966  0.0035 BR(K   e )=0.0514  0.0006 NA48KTeV KTeV measure 5 K L ratios  e3 /   3,  +-0 /  e3 ,  000 /  e3  +- /  e3,  00 /   These 6 decay modes account for 99.93% of K L decays and the ratio can be combined to extract BR (~6 million reconstructed K e3 ) (sample sizes 10 5 -10 6 )

14. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 BR comparison

15. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 V us from Kl3 decays and  L hep-ph/0411097 (F. Mescia @ICHEP04) 1) Quadratic parametrization of the form factor momentum dependence:       from KTeV + ISTRA 2) K L lifetime from KLOE (average of the two measurements) :  KL = (50.81  ns 3) BRs from KLOE (setting the sum =1): 4) Form factor f + K  (0) from Leutwyler-Roos: 0.961(8) BR(K L  e ) = 0.4007  0.0006  0.0014 BR(K L  ) = 0.2698  0.0006  0.0014

16. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 V us from Kl3 decays and  L KLOE results: |V us |  f + K  (0) (K Se3 ) = 0.2169  0.0017 |V us |  f + K  (0) (K Le3 ) = 0.2164  0.0007 |V us |  f + K  (0)(K L  3 ) = 0.2174  0.0009 From Unitarity : (1-|V ud | 2 ) 1/2 f + K  (0) = 0.2177  0.0028 | V us |  f + Kπ (0)

17. 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 frame Combining the experimental value of  (K  (  ))/  (  (  )) with the ratio f K /f  obtained from lattice calculations we can extract the ratio |V us |/|V ud | (Marciano hep-ph/0406324) Selection  e   

18. 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 

19. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 f K /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) V us from K +  + (  )

20. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005   (M K0  M K0 )  (M K0  M K0 ) SM prediction:  S 000 =  L 000 |  +  000 | 2 BR(K S  3  0 ) = 1.9 x 10  9 Best limit from: direct search SND ’99 : BR(K S  3  0 ) < 1.4 x 10  5 interference NA48 ’05: BR(K S  3  0 ) < 7.4 x 10  7 Uncertainty on K S  3  0 amplitude limits precision of CPT test: __ from unitarity   S,L =    ( 1 + i tan  SW )Re  f A*(K S  f) A(K L  f)/  S = (  i + tan  SW ) Im  MKMK MKMK  2 10    8 10   M K /M Planck = 4 10 -20 ) Observation of K S  3  0 signals CP violation in mixing and/or in decay: A limit on BR(K S  3  0 ) at 10  7 level translates into a 2.5-fold improvement on the accuracy of Im , i.e. K S   0  0  0 – test of CP and CPT

21. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Signal selection K S ’s tagged by of K crash 6 photons clusters, no tracks from IP Kinematic fit to improve cluster parameter Background rejection K S     + 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(K S ), P(K S ), c.m. angle between  0 ’s Final cut on residual K s energy: E(K s )-  E        Data MC 3  0 BR 10 -5 0 20 40 80 60 40 102030 : KLOE: Search for K S   0  0  0

22. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 K S   0  0  0 – Final Results KLOE: 450 pb -1 ’01+’02 data N sel (data) = 2 events selected as signal    = 24.5% N sel (bkg) = 3.13  0.82 stat  0.37 sys bkg events expected from MC N 2    BR(K S   0  0  0 ) =BR(K S   0  0 ) < 1.2 10 -7, N 3    Normalize signal counts to K S   0  0 count in the same data set: Can state: N 3  < 3.45 with a 90% CL

23. 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(K S   0  0  0 ) A(K L   0  0  0 ) Accepted for publication UL 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: K S   0  0  0 – Final Results

24. 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 K 0 -K 0 mixing: A S = 2Re  (CPT symmetry assumed) _ A S never measured before If CPT holds, A S =A L A S  A L signals CPT violation in mixing and/or decay with  S  Q  (K S,L   - e + )  (K S,L   + e - )  (K S,L   - e + )  (K S,L   + e - ) _ _ A S,L = Can extract |V us | via measurement of BR(K S   e ) Test of the  S =  Q rule,  (K S   e )/  (K L   e ) = 1 + 4 Re(x) K S   e decays – Physics issues

25. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 K S   e decays: Results Further rejection of K S   background from TOF identification Obtain number of signal events from a constrained likelihood fit to multiple data distributions Normalize to K S   in the same data set Use BR(K S   ) to calculate BR(K S   e ) Kinematic closure: use K L to obtain K S momentum P K and test for presence of neutrino: E miss =  M K 2 + P K 2 – E  – E e P miss = |P K – P  – P e |  Data — MC sig + bkg E miss  cP miss (MeV)

26. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 K S   e decays: Results Dependence of efficiencies on charge mainly due to TOF effects, estimated using data control sample of K L   e A S = (  2  9 stat  5 syst ) 10 -3 BR(K S    e + ) = (3.54  0.06 stat  0.04 syst ) 10 -4 BR(K S    e - ) = (3.55  0.05 stat  0.02 syst ) 10 -4 A L = (3.322  0.058  0.047) 10 -3 [KTeV 2002] A L = (3.317  0.070  0.072) 10 -3 [NA48 2003] Published result: (6.91  0.34 stat  0.15 syst ) 10 -4, KLOE ’02 BR(K S   e ) = (7.09  0.08 stat  0.05 syst ) 10 -4 Uncertainty in charge asymmetry still dominated by statistics With data for an integrated luminosity of 2.5 fb ,  A S  3 10   Re 

27. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 K S   e decays: Results Re(x) = (  2.7  3.0 stat  1.8 syst ) 10  Use BR(K L   e  ±  KTeV04] Re(x) = ( .1  3.2 stat  1.8 syst ) 10  Use BR(K L   e  ±  KLOE05  Use average of KTeV and NA48 measurement of the K S lifetime:  S = (89.62  0.05) ps Use new measurement of the K L lifetime:  L = (50.89  0.23) ns KLOE ’05 Compare  (K S   e ) with  (K L   e ): test of the  S  Q rule 4Re(x) =  (K S   e )/  (K L   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 

28. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Direct CP-violation in K 3   Matrix element parameterized in terms of slopes Kinematics Measured quantity sensitive to direct CP violation: Charged kaon: direct CP violation only |M(u,v)| 2 ~ 1 + gu + hu 2 + kv 2 A g = (g + -g - )/(g + +g - )≠0 u = (s 3 -s 0 )/m  2 =2m K ∙(m K /3-E odd )/m  2 ; v = (s 2 -s 1 )/m  2 = 2m K ∙(E 1 -E 2 )/m  2 s i = (P K -P  i ) 2, i=1,2,3 (3=odd  ); s 0 = (s 1 +s 2 +s 3 )/3. BR(K ±  ±  +   )=5.57%; BR(K ±  ±  0  0 )=1.73%.

29. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 10 -6 |A g | Experimental precisions by 2005: 10 -5 10 -4 10 -3 10 -2 SM SUSY Newphysics Ford et al. (1970) HyperCP prelim. (2000) TNF prelim. (2002) “neutral” mode NA48/2 proposal 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 ) [  A g ~10 -3 ] “charged” “neutral” Theory Theoretical expectations

30. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 NA48/2 goals and method M.S. Sozzi Primary NA48/2 goals:Primary NA48/2 goals: –Measure slope asymmetries in “charged” and “neutral” modes with accuracies δA g 2∙10 9 decays in “charged” mode and >10 8 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+2  gu) –Equalize K + and K – acceptances by frequently alternating polarities of relevant magnets. Δg = 2g∙A g

31. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 M.S. Sozzi |V| Data-taking 2003: 1.61x10 9 1.61x10 9 events selected K + : 1.03x10 9 events   M =1.7 MeV/c 2 Events M(3  ) GeV/c 2 U A g = (0.5±2.4 stat. ±2.1 stat.(trig.) ±2.1 syst. )x10 -4 = (0.5±3.8)x10 -4 NA48/2:Selected statistics 2003

32. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Cusp-like effect in K +  +  0  0 Interference generate a cusp in the  spectrum next to     threshold, not seen earlier by lower precision experiments One loop calculation: cusp located at m  = 2 m  + 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 M 0 = 1+gu/2 M 1  (a0 -a2) d  /dm   | M0 + M1 | 2 Two diagram contribute: direct emission,  re-scattering

33. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Cusp-like effect in K +  +  0  0 Best fit obtained with 2 loops and a small contribution from pionium fixed to: BR(K  pionium)/ BR(K  3  )  0.8 10 -5 (a0 -a2)·m   = 0.281 ± 0.007 (stat.) ±0.014 (syst.) ± 0.014 (theor.) NA48/2 prel NA48/2 2x10 8 K +  +  0  0 4x10 9 K +  +  –  + 2003-2004 50 days-2003 m 2 

34. 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) |V td | Rare Kaon Decays and the SM

35. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Status & Future programs K 0 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)

36. 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 K L and K S 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!!!

37. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005  20 20 0 0  40  60 40  Data — MC sig + bkg 6080 E miss –P miss (MeV) BR(K S   e ) = (7.09  0.07 stat  0.08 syst ) 10 -4 K S semileptonic decay Selected using Tof technique Event counting obtained by fitting the E(  e)-P distribution The two charge modes are measured independently selected ~10 4 signal events per charge in the 2001-2002 data sample.

38. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 W = m  (1019.4 MeV) L design 5  10 32 cm -2 s -1 DA  NE 2002: 270 pb -1 2001: 170 pb -1 2000: 20 pb -1 2004 best L peak 1.2 × 10 32 cm -2 s -1 2004 avg L ~6 × 10 31 cm -2 s -1 Collected 770 pb -1 since May 2004

39. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Conclusion The dominant K L BR’s with 0.5% accuracy The K L lifetime with 0.6% accuracy BR(K S   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 K S  BR Coming soon the update of  (K S  +  - (  ))/  (K S  0  0 ) measurement We expect to collect 2fb -1 for the end of December 2005 Final papers are under review by the Collaboration

40. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Unitarity test of CKM: V us Saga EXP: Need to measure BR, lifetime, and slopes with good accuracy TH : Need to improve estimate on f(0) exp th 0.3 %  0.4%  0.3% 0.8% K0 penK0 pen 0.6%  0.1%  0.3% 0.8% K penK pen 0.5%  0.4%  0.8% K 0  pmn  0.6%  0.9%  0.1%  1.5% 0.8% K   pmn  0.2% 

41. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 The KLOE detector Calorimeter  (E)/E = 5.7%/  E(GeV)  (t) = 54 ps/  E(GeV)  100 ps  p /p  0.4 % (tracks with  > 45°)  x hit  150  m (xy), 2 mm (z)  x vertex ~ 1 mm  (M  ) ~ 1 MeV

42. 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/K  3 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)

43. 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. K l3 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, m 2, from TOF measurement. m 2 =p 2  [(cT/L) 2 -1]  Ratio of data and MC efficiency is used to correct MC acceptance. KKKK  KKKK eeee  

44. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Semileptonic decays of K ± K +  +  0 Tag Tag K +  2Tag K +  2Tag K -  2Tag K -  2 N Ke3 67 022  331 26 774  21571 188  34525 942  211 NK3NK3 42 096  28216 586  17944 925  29316 465  180 m l 2 =p TRK 2  [(c(t l -t  )/L TRK ) 2 -1]

45. 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.

46. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Generators for radiative K decays  Motivation: acceptance evaluation with accuracy better than 1%, shape of kinematic variables (e.g. E miss -p miss 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: E731 (2.56  0.09)  10 -3 MC 2.6  10 -3

47. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 V us from Kl3 decays and  L KLOE results: |V us |  f + K  (0) (K Se3 ) = 0.2169  0.0017 |V us |  f + K  (0) (K Le3 ) = 0.2164  0.0007 |V us |  f + K  (0)(K L  3 ) = 0.2174  0.0009 From Unitarity : (1-|V ud | 2 ) 1/2 f + K  (0) = 0.2181  0.0022 New V ud | V us |  f + Kπ (0) New V ud

48. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 V us from Kl3 decays and  L 1-|V ud | 2 ) 1/2 f + 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)

49. Latest results on kaon physics A.Antonelli LNF-INFN - QCD@WORK Conversano June 2005 Kaons at KLOE K + K - 1.5  10 6 /pb -1 K L K S 10 6 /pb -1 The  decays at rest allow us to select monochromatic (p ~ 110 MeV/c) pure beams of Kaons Observation of K L,S signals presence of K S,L K S decays near IP: S ~ 0.6 cm ~50% of K L decays inside the detector: L ~ 340 cm ± ~ 95 cm Events per pb -1 : K S(+) K L(-)  ~4 m

50. 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 independent from B mesons… …and a large window of opportunity exists! G. Isidori Im t = A 2 5  Re t = A 2 5  V td