Claudio Gatti (KLOE Collaboration) LNF INFN

  • View

  • Download

Embed Size (px)


K decay measurements with the KLOE detector. Claudio Gatti (KLOE Collaboration) LNF INFN. XXII Rencontres de Physique de La Vallée d’Aoste Feb. 2008. u. W. l. g q V ud,s. g l. d, s. . . W. e. g . g e. . . Precision test of SM with kaons. - PowerPoint PPT Presentation

Text of Claudio Gatti (KLOE Collaboration) LNF INFN

  • Claudio Gatti (KLOE Collaboration) LNF INFNK decay measurements with the KLOE detector XXII Rencontres de Physique de La Valle dAoste Feb. 2008

  • Precision test of SM with kaonsC.Gatti - La Thuile 2008SM coupling to W Same coupling for all fermionsUnitary matrix(gqgl)2|Vud,s|2/MW4(gge)2 /MW4K, and nuclear decays decay(gqgl)2(|Vud|2+|Vus|2)= (gge)2 Left-handedTest of unitarity anduniversalityVub negligible

  • C.Gatti - La Thuile 2008Precision test of SM with kaonsBelieve in SM coupling to W: Test the presence of scalar and right-handed currents and presence of new gauge bosons.With recent precise experimental results and progress in theoretical predictions (lattice QCD, ChPT ...), kaon physics allows us to test the Standard Model at permil level, and probe new physics at the TeV scale.

  • Semileptonic kaon decaysC.Gatti - La Thuile 2008 For the extraction of |Vus| we need to measure (Kl3): from measurement of BRs and lifetimes.Ikl: from measurement of the t-dependence of form factors.All measurements taking into account radiated photons.

  • Leptonic kaon decaysC.Gatti - La Thuile 2008EM correctionRatio of K and decay constants Precise determination of the ratio |Vus|/|Vud| from Km2 and pm2 decay width.Combine measurement from Km2, pm2, Ke3, K3 and from nuclear decays to test electron-muon and lepton-quark universality and the unitarity of the CKM matrix.

  • The KLOE experimentC.Gatti - La Thuile 2008Electromagnetic Calorimeter (pb/sci)(E)/E = 5.7 %/E(GeV)(t) = 57 ps/E(GeV) 100 ps(x)~1 cmDrift Chamber (90%He 10% isobutane)sp/p = 0.4 % (tracks with q > 45)sxhit = 150 mm (xy), 2 mm (z)sxvertex ~ 1 mms(Mpp) ~ 1 MeVKS, K+ KL, K-K+K-BR~50%p=127 MeV=95 cmKSKLBR~30%p=110 MeVs=0.6 cm L=340 cmB=0.5 TIntegrated luminosityL=2.5 fb-1About 2.5109 KSKL

  • Simulation of the final state photonC.Gatti - La Thuile 2008Emission of final state photon included in the KLOE simulation.All measurements are inclusive of the final state radiation.Enriched Ke3 sampleDirect measurement of E in Ke3

  • Kaon TagC.Gatti - La Thuile 2008KL tagged by KS p+p-Efficiency ~ 70%s(PK) ~ 1 MeVKS tagged by KL interaction in EmCEfficiency ~ 30%s(PK) ~ 1 MeVK tagged by Kmn, pp identified by the secondary particle momentum in the K rest frame: p*(m) Trigger from the tag side.Tag~10%Absolute BRs: BR=Nobs/Ntag

  • KL,S decays and KL lifetimeC.Gatti - La Thuile 200813106 KL tagged decays.BR for 30, +-0, Ke3 and Km3, identifying photons in the calorimeter and fit to Emiss-pmiss from pTrk.tL measurement from BR dependency on FVDBR/BR=DL0.0128 ns-1 BR=1 Measurement of L from proper decay-time ditribution for KL 30.KL vertex from photon time of flight and KL direction.8.5 million decays in ~0.4L.400 106 KSKLBR for KSpenPID from time of flight.13,500 Ke3 events selected.Fit to Emiss-pmiss.First measurement of the charge asymmetryAS=(1.510)10-3

  • C.Gatti - La Thuile 2008BR(Ke3) 0.4008(15)BR(K3) 0.2699(14)BR(3p0) 0.1996(20)BR(p+p-p0) 0.1261(11)BR(p+p-) 1.964(21)10-3BR(p0p0) 8.49(9)10-4BR() 5.57(8)10-4L 50.84(23) nsAll correlations taken into accountOnly non-KLOE input BR(p0p0)/BR(p+p-)=0.43910.0013 PDG ETAFITBR(KL+-)(KL)=0.007275(68)BR(KL)(KL30)=0.00279(3)Other KLOE inputsBR(p+p-) 69.196(51)BR(p0p0) 30.687(51)BR(Ke+3) 3.517(58)10-4BR(Ke-3) 3.528(62)10-42/dof = 0.19/1BR(KS p+p-())/BR(KSp0p0)=2.2549(54)The sum of measured KS BRs isBR1-510-4KL,S decays and KL lifetime

  • K+m+n, p+p0C.Gatti - La Thuile 2008From 4 million tagged events.Found ~865,000 K2 events in 225
  • C.Gatti - La Thuile 2008K lifetimeWith 12 million tagged K, use 2 methods:K decay lenght t*= L KKcfrom DC info, taking into account dE/dX.K decay time t*= (t-L c)/Kfrom calorimeter info, measure photon time of flight. =(12.3470.030) ns- + = 1.0040.004PDG average 12.385(25) ns but CL 0.2%

  • K semileptonic decaysC.Gatti - La Thuile 200860 million tagged events.Apply kinematic cuts to reject background. Reconstruct photons and measure tK from tof.Measure lepton mass from tof and track momentum measurement.Counting from fit to m2l distribution.300,000 Ke3 and 160,000 Km3.Using lifetime from KLOE:BR(Ke3)=(4.9720.053)%BR(Km3)=(3.2370.039)%

  • Form Factor: K0e3C.Gatti - La Thuile 2008High purity Ke3 sample, 2 million events, selected by kinematics and time of flight.e by tof measure t=(pK-p)2Independent measurement for the two charge modes.Ke3 sensitive only to vector FF.t/m2+=(25.51.5stat1.0syst)10-3+=(1.40.7stat0.4syst)10-3P(2) ~ 90%Correlation 0.95MV=(8706stat7syst) MeVPole parametrization: P(2) ~ 92%

  • C.Gatti - La Thuile 2008Form Factor: K0m31.8 million Km3 selected.Sensitive to both vector and scalar FFs.Bakground rejection with kinematic cuts and tof.Difficult p/m separation: Fit to E spectrum, less sensitive (errors 2-3 times larger) combined fit with Ke3 data.Large correlations: impossible to measure 0.0=(15.42.2)10-32/ndf =2.3/2

    + + 0 1 -0.95 0.29 1 -0.38

  • C.Gatti - La Thuile 2008Form FactorsNew parametrizations based on dispersive relations (Bernard, Oertel, Passemar, Stern) and K scattering data: f+ and f0 depend only on parameters + and 0 respectively.+=(25.70.6stat+syst )10-30=(14.02.1stat+syst )10-32/ndf =2.6/3Correlation 0.26 Phase-space integrals change by 0.04% and 0.09% for Ke3 and Km3.Test of lattice QCDCallan-Treimanf0(tCT)=fK f+ CTCT O(10-3) (Gasser, Leutwyler)fK f=1.1890.007 (HPQCD/UKQCD)f+(0)=0.9670.025Compare with f+(0)=0.96440.0049 (RBC/UKQCD)

  • KLOE main publications related to VusC.Gatti - La Thuile 2008Charged Kaons JHEP 01 (2008) 073 d0.25% K+mn PLB632 (2006) 76 dBR BR~0.26%K pln JHEP Accepted dBR(l)BR~1.1%Neutral KaonsL PLB626 (2005) 15 d0.5%KL BRs PLB632 (2006) 43 dBR(l)BR~0.4-0.5%Kspen PLB636 (2006) 173 dBR(e)BR~1.3%Form factorsKe3 FF PLB636 (2006) 166 d~7% d50%Km3 FF JHEP 12 (2007) 105 d0014% dII~0.3-0.5%|Vus| and lepton universality @ KLOE arXiv:0802.3009

  • f+(0)|Vus| from KLOE resultsC.Gatti - La Thuile 2008KLe3 0.2155(7)KLm3 0.2167(9)KSe3 0.2153(14)Ke3 0.2152(13)Km3 0.2132(15)f+(0)|Vus|=0.21570.00062/ndf =7.0/4 (13%)All correlations taken into accountOnly non-KLOE input sComparing charged and neutral K decays: SU(2)=1.67(62)% (theory 2.36(22)%) Test of lepton universality:rme=1.0000.008From p and t decays 0.4%

  • Test of CKM unitarity with KLOE resultsC.Gatti - La Thuile 2008UsingFrom lattice QCD: f+(0)=0.96440.0049 (RBC/UKQCD)fK f=1.1890.007 (HPQCD/UKQCD)From 0+0+ nuclear b decays|Vud|=0.974180.00026And using G(pmn):|Vus|=0.22370.0013From Kl3 decays:|Vud|2+|Vus|2-1=-0.00090.0008|Vus|2|Vud|2=0.05410.0007From Km2:|Vus|=0.22490.0010|Vud|=0.974170.00026|Vud|2+|Vus|2-1=0.00040.00072/ndf =2.34/1 (13%)Combined fit result:Unitarity condition verified to 0.1%

  • Bounds on new physics from Km2 decayC.Gatti - La Thuile 2008From previous results:Unity in SM, affected by presence of scalar or right-handed currents.(Isidori, Paradisi)Rl23=1.0080.008We obtain:This places bounds on the charged Higgs mass and tan.Competitive and complementary to B decays.

  • C.Gatti - La Thuile 2008Bounds on new physics from Ke2 decayRK=G(Ken)/ G(Kmn)Accurate SM determination (0.04%)New physics effects up to 1% (Masiero, Paradisi, Petronzio).BR(Ken)~10-5 at most 4104 events. No tag requested.Background from Km2, selection using DC info (Mlep2) and calorimeter PID:

  • C.Gatti - La Thuile 2008Bounds on new physics from Ke2 decaytanbMH (GeV)Preliminary KLOE result with ~ 8100 observed events:RK=(2.550.05stat0.05syst)10-5We place bounds on the charged Higgs mass and tan, for different values of the slepton-mass matrix element D13.SM: 2.477(1)10-5 (Cirigliano, Rosell)NA48 preliminary: 2.43(4)10-5

  • ConclusionC.Gatti - La Thuile 2008We have measured: All the BRs for KL KS and K The form factor parameters in semileptonic KL decays The KL and K lifetimesWe obtain f+(0)|Vus|=0.21570.0006 with 0.3% accuracyWe test lepton universality: rme = gm2/ge2 =1.0000.008We measured the ratio |Vus/Vud fK/fp |2 = 0.76500.0033 with 0.4% accuracy.Using lattice QCD determinations for meson form factor and decay constants we obtain:|Vus|=0.22370.0013 and |Vus/Vud|=0.23260.0015 with 0.6% accuracyCombining with a fit these results with the evaluation of |Vud| from nuclear b decay we obtain |Vus|=0.22490.0010 with 0.4% accuracy.First-row CKM unitarity is satisfied to 0.1% (0.6s)With our results we are able to exclude a large region in the mH+-tanb plane.Preliminary results on the ratio BR(Ken)/BR(Kmn) allow a test LFV and the exclusion of a large region in the mH+-tanb plane.Complete dataset must still be analyzed, we expect improvements for lifetimes, BRs and FF parameters, as well as from the theory side (Lattice QCD, ChPT ......).

  • backupC.Gatti - La Thuile 2008f+(0)fK/fp

  • backupC.Gatti - La Thuile 2008