Unitarity and Universality

Transcription

1 Unitarity and Universality from Kaons with KLOE Paolo Franzini Roma, 4 April 2008

2 OUTLINE 1. Htory 2. Introduction 3. KLOE 4. K L, K S, K ± decays 5. V us 2 f + (0) 2 6. K µ2 /K π2 7. Unitarity and universality Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 2

3 Htory 1947: Rochester and Butler, K 0 π + π, K + π + π : Gell-Mann (Nijima) strangeness 1958: Gell-Mann and Feynman Universal V-A interaction. Λ peν 1.6%, Σ ne ν 5.6% 1958: Columbia-Pa: should see 6 events each, none found 1963: Cabibbo, s d mixing. sin θ c = : GIM, 2 quark family mixing 1973: Kobayashi and Maskawa, 3 quark family mixing : GWS, the standard model 2004: PDG, V ud 2 + V us 2 + V ub 2 < 1?? Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 3

4 Standard Model g 2 W + α (U L V CKM γ α D L + ē L γ α ν e L + µ L γ α ν µ L + τ L γ α ν τ L ) + h.c. There just one gauge coupling g, G F = g 2 /(4 2 M 2 W ) The quarks are mixed by a unitary matrix V Quarks and leptons have the same weak charge At the opposite extreme: g q, g e, g µ, g τ V not unitary (But probabilities are conserved!) U = V = u c t, D = d s b V ud V us V ub V ud V us V ub V ud V us V ub Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 4

5 Decay Width From f J α J α i Γ( S =1)= V us 2 G 2 F 1 (masses) F 2 (emi) F 3 (si). 1. F 1 : kinematics, spinor algebra, phase space, OK 2. F 2 : Cannot turn off electromagnetm. Lengthy but necessary. Few % correction, to 0.1% accuracy 3. F 3 : Strong interactions are hardest to compute, can have large effects, choose best processes, lattice to the rescue! Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 5

6 F 2 Radiation must be included m(γ) = 0 charge particles radiate. Take for example K S π + π. In the real world the em interaction 2 K gives Γ 1 K for ω The infinity cancelled by an opposite sign contribution:. 2 K K Γ 2 K K.. ( α Γ 1 + Γ 2 finite but contains a correction of O π log ω 0 m ω 0 finite and experimental acceptance dependent. ). Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 6

7 Radiation inclusive branching ratios Inclusion (or exclusion) of photons does affect event acceptance. It modern practice to give results fully inclusive of radiation up to the kinematic limit. Th requires correct accounting of radiation in the Monte Carlo detector simulation program. In the KLOE MC simulation, Geanfi, radiation included at the event generation level, event by event. In the following, even if not explicitly stated, BRs are totally inclusive of radiation. BR(K f(γ)) stands for BR(K f, f+γ, 0 < ω < ω max ) (I will also just use BR(K f)) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 7

8 F 3 SI Hadrons vs Quarks Nuclear β-decay. Look at transitions. No axial current. CVC helps with nuclear matrix elements. S = 1 decays. Corrections to f ūγ α s i appear only at 2 nd order in m s m d. A-G theorem. Kaon semileptonic decays. K πlν 0 0. Only vector part of current contributes to π ū L γ α s L K π ūγ α s K = f + (t)(p + p) α + f (t)(p p) α Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 8

9 ¼ p K P ` W k q P p k k ` e, ¹ Vector Current protected k 0 ( º π J α K =f + (0) (P + p) α f + (t)+ ( (P p) α f 0 (t) f + (t) ) ) t 0 = M 2 m 2 Form factor because K, π are not point like Scalar and vector FFs equal at t=0 (by construction) Factor out f + (0). f + (0) < 1 because K π f + (0) 1 1 (0.04) small SU(3) breaking f + (0) = f 0 (0) = 1 Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 9

10 Decay Width Γ(K l3(γ) ) = C2 K G2 F M K π 3 S EW V us 2 f + (0) 2 I Kl ( 1 + δ SU(2) ) K + δkl EM CK 2 = 1(1/2) for K0 (K ± ); S EW = (3), EW corr, Sirlin Measure: τ, BR, f +, f 0 Compute: χpt, Quark M, Lattice Define f + (0) as f K0 π ± + (0) δ SU(2) K (%) δkl EM(%) Ke (15) K e (22) +0.08(15) Kµ (15) K + µ3 2.36(22) +0.05(15) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 10

11 Phase space integral, K e3 ρ(e e, E ν ) [ M 2 G 2 CK 2 M 4 E e M spins I Kl ρ(e e E ν ) de e de ν zm E ν M + k k ] M 2 Γ = G2 CK 2 M K 5 xm(z) 768 π 3 dz f(t) 2 24 ((z + x 1)(1 x) α) dx zm xm(z) }{{} I Kl With 768 in the denominator, f(t)=1, all final state masses zero: I Kl = corresponds to 192 in muon decay rate. I Kl dimensionless. x = 2E e M, y = 2E ν M, z = 2E π M, α = m M End of introduction Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 11

12 DAΦNE An e + e collider operated (mostly) at W = M φ e + e φ { KS + K L 34.0% K + + K 49.3% Tagged, monochromatic, pure K S, K L, K +, K beams BR(K S πlν) = ( ) 10 4 BR(K ± πlν) = ( ) 10 2 BR(K L πlν) = ( ) 10 1 difficult so so best e µ Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 12

13 YOKE KLOE S.C. COIL Barrel EMC Cryostat DRIFT CHAMBER QCal End Cap EMC Pole Piece 7 m Paolo Franzini 6 m Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 13

14 Magnet SC Coil, B=0.6 T YOKE S.C. COIL Barrel EMC Cryostat DRIFT CHAMBER QCal End Cap EMC Pole Piece 7 m Paolo Franzini 6 m Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 14

15 Magnet SC Coil, B=0.6 T EM Calor. Pb scint fiber 4880 pm, 2440 cells YOKE S.C. COIL Barrel EMC DRIFT CHAMBER QCal Cryostat End Cap EMC Pole Piece 7 m Paolo Franzini 6 m Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 15

16 Magnet SC Coil, B=0.6 T EM Calor. Pb scint fiber 4880 pm, 2440 cells Drift Ch sense wires tot wires Carbon fiber walls YOKE S.C. COIL Barrel EMC DRIFT CHAMBER QCal Cryostat End Cap EMC Pole Piece 7 m Paolo Franzini 6 m Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 16

17 Magnet SC Coil, B=0.6 T EM Calor. Pb scint fiber 4880 pm, 2440 cells Drift Ch sense wires tot wires Carbon fiber walls YOKE S.C. COIL Barrel EMC DRIFT CHAMBER QCal Cryostat End Cap EMC Pole Piece 7 m Al-Be beam pipe r=10 cm, 0.5 mm thick Paolo Franzini 6 m Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 17

18 σ E /E =5.7%/ E (GeV) σ t = 54/ E (GeV) ps Drift chamber EM Calorimeter σ(p )/p = 0.4% σ x,y =150 µm; σ z =2 mm Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 18

19 KLOE precion measurements M(K 0 ) = 497, 583 ± 5 ± 20 kev M(η) = 547, 874 ± 7 ± 29 kev Using M(φ) measurements based on electron anomaly a e = ± , Novosibirsk KLOE calibration KLOE continuously calibrated with data Time, energy and position scales are calibrated every 1-2 hours Machine energy, collion point, p(φ) in lab Together with L and Ldt, all provided to DAΦNE Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 19

20 Analys Prefilter. Reconstruction 2 hours after data taking Initial classification Massive Monte Carlo production. MC includes run by run background simulation Tracking efficiency measured from data Photon efficiency measured from data Signal shapes and backgrounds from control samples Continuous improvement of MC with feedback from physics analys Particle ID by time of flight Particle ID by shape of energy release in EMC cells Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 20

21 Measuring BRs We only measure absolute BR, i.e. Γ i /Γ, not ratios (Γ i /Γ j ) of partial rates. We have three ways to do it: 1. Measure single BR s 2. Measure (almost) all BR 3. Measure all partial rates: BRs & Γ = 1/τ We only use tagged kaons. Trigger efficiency must not depend on decay mode of tagged kaon. For every event, we verify the trigger was due to the tagging kaon. There are differences between K S, K L and K ± : 1. 1 vs 2 charged decay products 2. Tag by 1 or 2 body decays 3. Tag by time of flight Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 21

22 The K S beam First level, crude K S tag by K L TOF 50% of the K L -mesons reach the calorimeter where most interact. Since β(k 0 ) 0.2, we identify kaon interactions by TOF ¼ 0 ¼ 0 ¼ + ¼ K L interacting in the calorimeter give an ideal K S tag, almost independent of 1 RF bucket * ( K ) L K S decay mode. The value of T 0 here obtained from the first particle to reach the calorimeter. π, µ, γ or e Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 22

23 K S π ± e ν = = or t =700 ps ( K L ) W(DA NE)=1 MeV gives =0.004 After event reconstruction very clean signal tags the presence of K S. Search for two track decays near IP. Reject K S π + π. Use TOF difference for two tracks taken as π e or e π. Provides electron ID and charge of lepton. Use E ms p ms to olate K S, e3 events. Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 23

24 K S πeν, Evts/1 MeV e 800 Evts/1 MeV e 600 Data Signal - MC fit Bckgnd - MC fit 600 Data Signal - MC fit Bckgnd - MC fit Ep ms (MeV) Ep ms (MeV) ,000 signal events BR(K S πeν)=(7.046 ± 0.091) 10 4 V us to 0.7% CMD-2 '99 Events DE, MeV Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 24

25 We know (KLOE, PDG, etc) Dominant K L decay modes Σ B = BR(K L e3 ) + BR(K Lµ3 ) + BR(K L 3π 0 ) + BR(K L π + π π 0 ) = (± ) We assume We measure: τ(k L ) = 51.7 ns Σ B = GOOD! We can solve for : { 4 BRs K L lifetime Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 25

26 A step at a time Detect K S π + π, tagged K L beam Find: a) K L 2 charged particles: b) K L 3π 0 Classify a) as eπν, µπν, π + π π 0, π + π Determine tag bias corrections Determine FV acceptance & all other efficiencies Count in FV. FV: 35 < x, y < 150 cm, z < 120 cm y x z All the above requires knowledge of τ. Use old value τ 0 =51.7 ns. In KLOE, ) A FV = A 0 FV ( ns 1 (τ 0 τ) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 26

27 Solve for BRs and lifetime BR(K L e3 ) = ± BR(K L µ3 ) = ± BR(K L 3π 0 ) = ± BR(K L + 0 ) = ± There are of course correlations τ(k L ) = ± 0.37 ns Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 27

28 K L two track events Events 0.5 MeV Ke 3 K 3 Data For K L π ± l ν: E ms 0 p ms 0 m ν =0 =E ms p ms = µπ =smallest of µ + π, π + µ 2000 Fit to MC shapes Count, BRs 14 sub-samples (MeV) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 28

29 10 5 Events 0.5 MeV Data Select electrons 10 4 K e3 Ke3 + E MeV 10 3 K e (MeV) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 29

30 Select muons 10 5 Events/0.5 MeV Data 10 4 K e3 K (MeV) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 30

31 K L π 0 π 0 π 0 Count tagged K L decaying to 3γ, 4γ, 5γ, 6γ,7γ Efficiency O(100%) MC corrections Background O(0.001) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 31

32 Time dependence of K L π 0 π 0 π counts/0.5 ns K L million ev fit region» 0.4 L τ(k L ) = ± 0.30 ns t*( K) (ns) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 32

33 All KLOE K L results Param. Value Correlation coefficients BR(K L e3 ) (15) BR(K L µ3 ) (14) 0.31 BR(3π 0 ) (20) BR( + 0 ) (11) BR(π + π ) 1.96(2) BR(π 0 π 0 ) 8.49(9) BR(γγ) 5.57(8) τ L 50.84(23) ns We can do it! When PDG does it, combining inconstent results from different experiments it can be a daster!!! Till 06 they could not input correlations. Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 33

34 PDG Example 1. BR(K 3π 0 ). NA31 95: ± PDG 04: ± : ± σ to 6.8σ off! 2. 3π 0 /K e3 NA31 95 and PDG σ to 7.6σ off! 3. BR(K ± π + π 0 ). Chiang 72: ± PDG 04: ± :.2064± σ to 3.2σ off! BR( K ¼2 + ) BR( K e3 + ) 4. PDG 04 PDG 06 End 07 PDG 04 PDG 06 End Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 34

35 PDG masses 5. η mass. The PDG procedure should give m(η)=547.53±0.26 MeV, CL= They include 3 old measurements which should give m(η)=547.51±0.13 MeV, CL= They give m(η)= ±0.18 MeV, CL=0.001??? 6. K + mass. PDG procedure m(k + )= ±0.012 from 6 values. From only last two m(k + )= ± They give ± Also CL ( ), they give CL= Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 35

36 K ± decays A K ± e3 decay ¹ e K K Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 36

37 K ± l3 decays Tag Decay K + µ + ν K π 0 e ν K + π + π 0 K π 0 µ ν K µ ν K + π 0 e + ν K π π 0 K + π 0 µ + ν Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 37

38 Tagging decays and K ± µν decays Ev/MeV ` p* (MeV/c) Compute CM momentum using m(π). The µν decay peak dtorted but quite recognizable for tagging. We also get BR(K µν(γ)) and BR(K ππ 0 (γ)) Note the radiative tail! Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 38

39 . K µν(γ) BR Ev/MeV/c All background decays, contain a π 0. The background shape obtained from a control sample p* (MeV/c) K µ2 events are counted only in the shaded area, after background subtraction, 2%. BR(K + µ + ν(γ)) = ±0.0009± Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 39

40 300 k 200 k No π 0 requirement! Counts/MeV ¼ + ¼ Data Fit K ± π + π 0 decays Measuring the K π detection efficiency inner DC wall E M C K D 100 k p*( ¼ ) (MeV) ¹ K ¼ d BR(K + π + π 0 (γ)) = ± stat ± syst Average of K µ2 and K π2 tags. Normalization for many K± BRs Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 40

41 K ± l3 decays Counts / 14 MeV k k K e3 K 3 Data Fit to MC shapes K µν and K π ± π 0 tag. Verify π 0 2γ. Lepton mass from p and TOF. M 2 (MeV 2 ) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 41

42 K ± l ± π 0 ν BRs BR \ Tag K + µ2 K + π2 K µ2 K π2 BR(K e3 ) (7) (10) (8) (10) BR(K µ3 ) (6) (9) (5) (9) 8 measurements, very good constency: BR(K ± e ± π 0 ν) = ± BR(K ± µ ± π 0 ν) = ± Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 42

43 All KLOE K ± results Constrained fit: BR(K ± µ ± ν) = ± BR(K ± π ± π 0 ) = ± BR(K ± π ± π + π ) = ± (input PDG 04) BR(K ± e ± π 0 ν) = ± BR(K ± µ ± π 0 ν) = ± BR(K ± π ± π 0 π 0 ) = ± sum = 1.0 χ 2 /dof = 0.78/1, CL=38% Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 43

44 Must check τ(k ± ) ns Koptev, U 95 Koptev, Cu 95 Ott 71 Lobkowitz 69 Fitch 65B ns 12.6 δτ= ns ns Better remeasure! Ott et al.: error 0.032, not Koptev: τ =12.422±0.048 Lobkowicz way off τ = ± ns Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 44

45 KLOE τ(k ± ) 120 k 100 k 80 k 60 k 40 k 20 k events/ns K l Fit range fit data 70 k 60 k 50 k 40 k 30 k 20 k 10 k events/ns K t Fit range fit data 4 measurement of τ 140 k 120 k 100k 80 k 60 k 40 k 20 k events/ns t * (ns) 40 K l Fit range fit data t * (ns) k events/ns 70 k K t 60 k fit data 50 k 40 k 30 k 20 k 10 k Fit range Constent Can average Use only our result t* (ns) t* (ns) 50 τ(k ± ) = ± 0.030, 0.25% τ(k + )/τ(k ± ) = ± Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 45

46 The form factors f +,0 (t)?? Phase Space Integrals I Kl t = (P p) 2 = M 2 + m 2 2M E π, 0 < t < M 2 + m 2 for K e3 No need to fit Dalitz Plot. All info in E π spectrum d /dz 2 (FF ) g( z) d /dz g( z ) f(t( z)) 2 1 f(t( z)) 2 z 2 1 g( z) z z = 2 E π M Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 46

47 FF: quadratic, pole, dp. f + (t) = 1 + λ t ( ) m + λ t 2 or f + (t) = M V 2 2 m t MV 2 λ, λ are 95% correlated, errors from fit from M V λ = (m/m V ) 2, λ = 2 λ 2 Pole and quad give different I, KTeV, 04 KTeV unlucky, but should have understood. Pole was right!! Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 47

48 Common practice Quadratic FF + and linear FF 0 : three parameters λ +, λ +, λ Th systematically N over-estimates λ 0 by 20%. Errors look acceptable. λ 0 λ 0 λ + λ N 1 Errors are unacceptable, correlations reach %!! NEED HELP! Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 48

49 Dpersive approach Use a dpersion relation for log( f + (t)), twice subtracted at t=0. f + (t) = exp [ (t/m 2 )(λ + + H(t)) ]. λ + slope at t=0 to be measured. H(t) obtained from Kπ p-wave phase, dominated by K (892). f + expands to t f + = 1 + λ + m 2 + λ ( ) t 2 2 m 2 + λ λ ( t 6 The Callan-Treiman relation relates the scalar FF at t = Kπ to the ratio of the pseudoscalar decay constants f K /f π. f 0 ( Kπ ) = f K 1 f π f + (0) + CT where Kπ = M 2 m 2, the so called Callan-Treiman point, and CT a correction which at NLO in χpt Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 49 m 2 ) 3

50 Use dpersion relation subtracted at t=0 and t = Kπ. Use s- wave Kπ phases to compute the equivalent function G(t). f 0 (t) expands to t f + = 1 + λ + m 2 + λ ( ) t 2 2 m 2 + λ λ ( t 6 (Use dpersion relations and χpt: Stern et al.. Also Pich et al..) FFs are power series in t but with only one free parameter each! m 2 Fit for λ +,0 and get phase space integrals ) 3 I(K 0 e3 ) I(K0 µ3 ) I(K+ e3 ) I(K+ µ3 ) (14) (18) (14) (18) 0.2 to 0.4 %. 1/3 of KTeV error. Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 50

51 [Γ] f(0) V us We are almost there. Let us begin with f(0) V us. f(0), by definition, belongs to K 0 π ±. If we know the I-spin corrections and the long dtance EM corrections all decays must give the same value for f(0) V us. Th in fact a check of the δ... estimates and of the experiment. We find Channel f(0) V us Correlation coefficients K Le (7) K Lµ (9) 0.28 K Se (14) K e3 ± (13) K µ3 ± (15) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 51

52 f(0) V us f + (0) V us K Le3 K K L 3 Se3 K e3 K 3 = ± χ 2 /ndf =7.0/4 (CL=13%) SU(2) corrections are verified to 1.1 σ Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 52

53 Lepton Universality From: R µe [f(0)v us] 2 µ3 [f(0)v us ] 2 e3 = Γ µ3 Γ e3 I e3 (1 + δ e ) 2 I µ3 (1 + δ µ ) 2 [Γ] R µe = g2 e g 2 µ = ± [W α J α ] Competitive with pure leptonic processes, τ decays (R µe ) τ = ± Also with π lν results (R µe ) π = ± Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 53

54 f(0) and V us The accepted value was f(0) = 0.961±0.008, Roos & Leutwyler, Recently Lattice results have become convicing. We take f(0) = ± , RBC and UKQCD, Then V us = ± V us 2 = ± and V ud 2 V ud 2 = ± V us 2 V ud 2 = ± ( 1.1σ) But we can do better Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 54

55 K µν/π µν Γ(K µ2(γ) ) Γ(π µ2(γ) ) = V us 2 V ud 2 f 2 K f 2 π ( m K 1 m 2 µ /m 2 ) 2 K ( m π 1 m 2 µ /m 2 ) 2 ( ± ) π Cancellations in f 2 K /f 2 π. From lattice Cancellations in rad. cor. From Marciano. KLOE V us /V ud f K /f π 2 = ± HPQCD/UKQCD f K /f π =1.189±0.007 V us /V ud 2 = ± Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 55

56 CKM Unitarity V us K ¹º ¼ ¹º K ¼`º 1¾ contour -decay unitarity V ud Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 56

57 From the fit 1 V us 2 V ud 2 = ± ( 0.6σ) V us = ± V ud = ± Fit with unitarity as constraint V us = ± V ud = 1 V us 2 = ± θ C = ± 0.06 Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 57

58 tan β M(Higgs ± ) tan( ) R l23 = V us (K µ2 ) V us (K l3 ) V ud( ) V ud (π µ2 ) = 1 in the SM. With charged Higgs exchange R l23 = % CL from B 95% CL from K Charged Higgs mass (GeV) ( ) 1 m2 K + m 2 1 m2 π + H + m 2 K + tan2 β 1 + ɛ 0 tan β ɛ 0 1/(16π 2 ) Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 58

59 Conclusions Unitarity verified at the 0.1% level 1 V us 2 V ud 2 = ± Muons, electrons and quarks carry the same weak charge to better than 0.5% Kaon properties limit the parameter space for some new physics models Roma, 4 April 2008 Paolo Franzini - Kaons and Kloe 59