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K charged status report

K charged status report. P.Branchini, E.De Lucia, P.De Simone, E.Gorini, A.Ferrari M.Martemianov, L.Passalacqua, M.Primavera, B.Sciascia, A.Ventura, R.Versaci, V.Patera. DE/Dx development vs PiD (next talk by E.De Lucia) K e3 studies: initial design of efficiency measurement from data

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K charged status report

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  1. K charged status report P.Branchini, E.De Lucia, P.De Simone, E.Gorini, A.Ferrari M.Martemianov, L.Passalacqua, M.Primavera, B.Sciascia, A.Ventura, R.Versaci, V.Patera • DE/Dx development vs PiD (next talk by E.De Lucia) • Ke3 studies: initial design of efficiency measurement from data • Kl4 analysis skeleton • K± p±p0p0 analysis refinement • Improvement ofskkby means of K± p±p0 (already presented by M.Dreucci on Friday) • Kmn studies: skk by means of K± mn and Br(Kmn)/Br(Kpp) (very early stage yet) KLOE GM Capri 23-25 May 2003

  2. Triggering tag on one side • K decay vertex • 0in EMC • e± id :ToF,Kin,De/Dx Ke3 analysis steps: The first and the third steps have been studied in the context of the sKK and K±p±p0p0 analysis. We started to develop methods to extract efficiency and systematics for the other steps (possibly from the data) KLOE GM Capri 23-25 May 2003

  3. fit tracce + vertice K+ K+0 Kl3 (segnale) K+00 p(MeV/c) Ke3 :tracking & vertex efficiency We study a method to measure on data the efficiency to identify a K charged decay in the DC: edecay= etrackKx etrackdaughterxevert indifferent kinematical region of the Ke3 spectrum using other K± decay with overlapping spectrum The aim is to select a sample of events where the vertex in the DC can be detected by means of ECAL quantities. We select a sample of mn tagged events and look at the other side KLOE GM Capri 23-25 May 2003

  4. tg tg tg tg p0 p0 p± Kmntag Kmntag p0 p0 tg tg tg Ke3: edecay @ low charged momentum by meand of g’s Tof (Kp±p0p0) In the Kp±p0p0 decay, the times of the 4 g clusters from 2 p0 give the decay vertex position with fair accuracy r vertex (cm) few pb The method has been successfully used in Kp±p0p0 analysis but has low efficiency and gives only the integrated edecay on the low end of ke3 spectrum Dx vertex (cm) KLOE GM Capri 23-25 May 2003

  5. Ke3: edecay @ high momentum with K momentum extrapolation (Kp±p0) tp The 4 g’s Tof method cannot be applied to the high end of the Ke3→ only one p0 ! We are exploring the possibility to use the info from the tag side. A REFINED DE/DX (!!) is required by K crossing the DC wall and BP. p± pK Kmn tag tg t0 pK tm p0 • From the tag side by means of extrapolation of the Kaons momentum with we obtain: • Timingof the signal K in the DC • Position of the signal K in DC • Momentum of the signal K in the DC tg Only events with 4 clusters and Ecl > 50 MeV KLOE GM Capri 23-25 May 2003

  6. Ke3: edecay & K momentum extrapolationposition resolution Ke3: edecay & K momentum extrapolationposition resolution Ke3: edecay & K momentum extrapolationposition resolution The check on the resolution achieved on the extrapolated position of the signal K has been made on double tag event (K→mn-K→pp0). The extrapolation from the mn tag side is compared with the fitted position and momentum of the signal (pp0) kaon at first hit in DC. s < 1 cm Dx at first hit (cm) ~ 4 pb-1 ; 2002 data Tails are expected mainly due to Landau fluctuations in dc wall energy loss Dr at first hit (cm) KLOE GM Capri 23-25 May 2003

  7. s = 6 Mev/c Dp at first hit (MeV/c) s = 4 Mev/c Dpx at first hit (MeV/c) Dq at first hit (deg) Ke3: edecay & K momentum extrapolationmomentum resolution Ehm.. failed fit with 2 gaussian !! The extrapolation can be further optimized. Up to now it has been made using solenoidal constant B field… Must be taken into account that errors on signal K momentum and position are correlated. tg KLOE GM Capri 23-25 May 2003

  8. R (cm) Dx vertex (cm) Dr vertex (cm) Z (cm) Vertex position Ke3: edecay& K momentum extrapolation: vertex resolution The unknown decay path of the signal K along the extrapolated helix can be found imposing the consistency on the p0 invariant mass, on the K and gs tof. Found the vertex, the g cluster energy and position gives the p0 momentum. Then, with the K momentum at the vertex we obtain the p± momentum. KLOE GM Capri 23-25 May 2003

  9. tp p± pK pp±=pK- pp0 Kmn tag tg pp0 pK tm p0 tg Ke3: edecay& K momentum extrapolation: p± momentum resolution The results obtained are based on a toy c2 evaluation without using the info from the charged cluster: Starting point for a fit constrained. Dpx p± (Mev/c) • good resolution on pp± is needed to: • Correctly evaluate the edecay with respect of charged pion momentum • Reject the kl3 decay using the position and the time of the 4th cluster ( should be the charged one…) To be continued….. KLOE GM Capri 23-25 May 2003

  10. Ke3 : possible Pid for e± Possible strategies for electron ID relies on kinematic cuts, Tof, De/dx , different behaviour in ECAL ( see M.Testa talk) or a mixture of some of them. The approach is to use an ECAL based separation method to extract the signal and a DC driven separation method to check systematics, or vice versa with no use of MC. For more details on possible use of DE/Dx I refer to Erika presentation. Mass from ToF (Mev**2) P* (MeV/c) b KLOE GM Capri 23-25 May 2003

  11. Update of BR(K00) analysis • The work done until December 2002 (112 pb–1) was reported in full detail in KLOE Memo # 279 • Referee’s comments have brought to revise some of the requirements/techniques used in the analysis. • A larger data sample (all 2001-02 statistics) has been used 1) to improve final uncertainty ; 2) to avoid statistical correlations between control samples. Now 240 out of 411 pb-1 are now used for the control samples and the rest for the signal measurement. • The control sample for estimating K has been redefined to better take into account the effect of nuclear interactions . KLOE GM Capri 23-25 May 2003

  12. Results and conclusions Event yield N’(pp0tag)=30798±100, Npp°tag=(1275±4)103 N’(mntag)=52253±230, Nmntag=(1992±4)103 Lint = 441 pb–1 BR(K00)= (1.781  0.013stat  0.016syst)% PDG fit 2002:(1.73  0.04)% • KLOE Memo # 279  KLOE Note # 187 • A preliminary version of the draft is ready KLOE GM Capri 23-25 May 2003

  13. The Ke4’ decay analysis Very preliminary Ljung 73 2 evts /Ke3+ Bolotov 86 25 evts /Ke3– Barmin 88 10 evts /K+all PDG: BR=(2.10.4)10–5 The Ke4’ BR can be measured using the absolute t’ BR obtained at KLOE and measuring the Ratio:(Ke4’) / (’) ’ K   0 0 Ke4’  K  e00e KLOE GM Capri 23-25 May 2003

  14. Preselection : 4LEVEL • Trigger: EMC + Cosmic Veto • Event Classification: kpmstream(all the 5 algo’s) • A 2-track vertex V in DC volume with a K track • Helix distance between the two tracks’ first/last hit and V:t2v<50cm • 4 “ontime” neutral clusters with Ei>15MeV, such that: tij |ti–tj–(rVi–rVj)/c|<4t(Ei,Ej) i,j=1,..,4 and tij<10ns • Pairing of the two 0’s by minimizing ij [(mij – m°)/m°]2 • 80 MeV < m12 , m34 < 190 MeV p0p0 Ch track KLOE GM Capri 23-25 May 2003

  15. ’ selection  • |pdau| < 135 MeVin K± frame • 450 MeV < m3 < 540 MeV • KPP0P0FITbased on 6 contributions: E , p , s0 . 2’ /6 < 5s0(s1+s2+s3)/3 , si  (pK – pi)2  Ke4’ selection • A cluster associated to the daughter track • |s0(’ hyp.) – 105 MeV2| < 8103 MeV2 • KEP0P0NUFITbased on: E conservation in  mass hypothesis, missing mass 0, daughter: p/E1, daughter: t.o.f. compatible with e (not  or ). 2e4’ /4 < 3.75 , 2’ /6 > 1 KLOE GM Capri 23-25 May 2003

  16. KLOE note # 187 Measuring BR(Ke4’) ~ 1 at %1 (MC check) From t’ new Nobs= selected events in the final Ke4’ sample Nbckg= background events expected in the final data sample N’= finally selected ’ events ’= background contamination in ’ events trig ,filt ,K ,vtx ,clu= “4LEVEL” efficiencies for Ke4’ and ’ events 135= cut |pdau|<135 MeV in K frame, m hyp.  ’ ac=e±track-to-cluster efficiency  Ke4’ fitx= kinematic fit efficiency x = ’ , Ke4’ BR(’)= (1.781  0.013stat  0.016syst)% KLOE GM Capri 23-25 May 2003

  17. Data and Monte Carlo samples Data :441 pb–1(June 2001 – September 2002) MC :2.6 107all (~9 pb–1) 2.0 105K+K–, K±e±00e,KŦall (~3.2 fb–1) 2.0 107K+K–, K±±00,KŦall (~380 pb–1) 1.2 107K+K–, K±e±0e,KŦall (~82 pb–1) 1.2 107K+K–,K±0,e0e,0(~100 pb–1) KLOE GM Capri 23-25 May 2003

  18. Ke4’efficiencies e track to cluster association <ac> = 0.359 0.011 • ac (pe) obtained from Ke3 and • integrated over pe distribution in Ke4’’ Kinematic fit(MC) fite4’ = 0.237  0.006 • Systematics include the choices • of the 2e4’ cut and definitions. • The efficiency includes the effect • ofthe s0 cut (in ’ hyp.) : (981)% KLOE GM Capri 23-25 May 2003

  19. Nbckg (’) = 11715 (MC and Data) Nbckg (non-’) = 359 (MC and Data) Nbckg = 15218 Background evaluation • In 441 pb–1 the following contaminations from K+K– are expected (MC): • Additional bckg from K2andKl3 : 5evts • ’ = 0.60.1 % Nbckg = 12017 KLOE GM Capri 23-25 May 2003

  20. Nobs = 407  20 Nbckg = 152  18 N’ = 899020  950  6300 Nsig = 255  27  Preliminary results NO DE/Dx applied !!! tot’/tote4’ = 4.800.03 VERY PRELIMINARY BR(Ke4’) = (2.43  0.20stat  0.22syst )10–5 PDG fit: (2.10.4)10–5 Barmin 88: (2.540.89)10–5 KLOE GM Capri 23-25 May 2003

  21. Capri analysis K±→p±p0 vertex 3 pb-1 sample Tof K (ns) tK = 12.8 ns tKPDG = 12.4ns Summary • sKK and t’ analysis finalized • Ke3 analysis started • Kl4 analysis on the way • Help from DC ADC’s can be there • The K →mn sector must still be exploited KLOE GM Capri 23-25 May 2003

  22. Perspectives • Increase Monte Carlo generation to improve the knowledge of background • Perform data-extracted efficiencies to correct the MC predictions • A KLOE memo will be ready by summer 2003 • Analysisstatuswillbe reported (July) in PhD thesis Studies on the charged kaon decays K  00 and K  e00e(e) with the KLOE experiment – KLOE GM Capri 23-25 May 2003

  23. MC 4LEVEL efficiencies (I) Trigger(Data) Event Classification(MC) trig’/trige4’=1.020.020.01 filt’/filte4’ = 1.0060.011 • |1 – trig’/trige4’| < • |1 – selftrig’/selftrige4’| Kaon identification(MC) K’/Ke4’ = 0.9920.013 KLOE GM Capri 23-25 May 2003

  24. 4LEVEL efficiencies (II) Vertexing(MC) vtx’/vtxe4’ = 1.0160.005 • Small dependence of vtxon the angle • between K and daughter’s directions Clustering(MC) clu’/clue4’ = 1.0070.007 • The efficiencies of “ontime” and • m cuts have been checked to • coincide at % level for’ andKe4’’ KLOE GM Capri 23-25 May 2003

  25. ’efficiencies |pdau|<135 MeV requirement 135 = 0.972 0.002 • Already studied for’ • in KLOE Note # 187 • Computed on data at • 4LEVEL (99.3% ’) • Includes the cut on m3 Kinematic fit(Data and MC) fit’ = 0.403  0.002 KLOE GM Capri 23-25 May 2003

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