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Risultati recenti dell’esperimento KLOE alla f -factory DA F NE - Frascati

Risultati recenti dell’esperimento KLOE alla f -factory DA F NE - Frascati. Antonio Passeri INFN Sezione Roma III passeri@roma3.infn.it A nome della collaborazione KLOE. XCI Congresso Nazionale della Società Italiana di Fisica Catania, 26 settembre 2005. The DA F NE f -factory.

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Risultati recenti dell’esperimento KLOE alla f -factory DA F NE - Frascati

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  1. Risultati recenti dell’esperimento KLOE alla f-factory DAFNE - Frascati AntonioPasseri INFN Sezione Roma III passeri@roma3.infn.it A nome della collaborazione KLOE XCI Congresso Nazionale della Società Italiana di Fisica Catania, 26 settembre 2005 Risultati recenti di KLOE

  2. The DAFNE f-factory • Ebeam 510 MeV • 2 separate rings for e+ and e- to minimize beam-beam • high current (20 mA per bunch) • up to 120 bunches • Crossing at 12.5 mrad angle Risultati recenti di KLOE

  3. Excellent running at beginning of september: peak luminosity: 1.4 1032 integrated lum: 90 pb-1 in 15 days KLOE data sample Only 2001-02 sample Analyzed so far. Plan to run up to end 2005 on peak (expect 2 fb-1 for 2004-05 data overall) An off peak run planned in 2006 Risultati recenti di KLOE

  4. B = 0.52 T 4m-, 3.75m-length, all-stereo sp/p = 0.4 % (tracks with q > 45°) sxhit = 150 mm (xy), 2 mm (z) sxvertex ~1 mm • sE/E = 5.7% / E(GeV) • sT = 54 ps / E(GeV)  50 ps • PID capabilities mostly from TOF • sL(gg) ~ 1.5 cm(p0 from KLp+p-p0) KLOE detector performances Risultati recenti di KLOE

  5. 0- 1- 0+ f(1020) g BR 83% a0(980) KK g g f0(980) p0 h'(960) p g w(780) BR 1.3% BR 15% r(770) h(550) g p0 pp KLOE Physics • Main focus on KAON physics • CP double ratio/interferometry • CPT test with semileptonicKs,KLchargeasymmetries • Vus , kaon form factors from semileptonic KS,L ,K decays • Rare KS,L decays • ( KS3p0, p+p-p0 , KL gg...) • Non Kaon Physics • radiative f decays (scalars, pseudoscalars + photon) • rp final states • hadronic cross section Risultati recenti di KLOE

  6. The presence of one kaon tags the other one on the opposite side All KS decaynear the i.p. Advantages of f-factory environment • Decays K+K– 49.1% KLKS 34.3%  15.4%  1.3% • The final KK statehas the samequantum numbers as the f i.e. is a pureJPC = 1- - quantum state • PK=-PK ~110 MeV/c • l(KS) = 6 mm (t = 90 ps), l(KL) = 3.5 m (t =51.7 ns) KLOE has the unique capability of selecting pure KS and KL beams Risultati recenti di KLOE

  7. KS(L) p+p- at t1 f KL(S) p+p- at t2 +0.038 -0.035 zS,L = 0.043 0.008 Kaon interferometry and QM coherence I(Dt)  e-GL|Dt|+e-GS|Dt|- 2(1 - zS,L)e-(GS+ GL)|Dt|/2 cos(DmDt) • KLOE preliminary • 380 pb-1 ’01 + ’02 data • Fit with PDG values for GS, GL: • Dm = (5.34  0.34) × 109ħ s-1 • PDG ’04: (5.301  0.016) × 109ħ s-1 • Fix Dm to PDG ’04 value, obtain: • Data: 7366 evts • Fit: c2/dof = 15.1/22 Coherent KL regeneration on beam pipe Peak position sensitive to Dm No simultaneous events: same final state/ antisymmetric initial state cf. Bertlmann ’99 (CPLEAR): +0.16 -0.15 zS,L = 0.13 |t1-t2|/tS Risultati recenti di KLOE

  8. KL“crash” • = 0.22 (TOF) KS p+p- KS p-e+n KL 2p0 KS and KL “beams” • KL tag by requiring two opposite • charge tracks from IP • Loose cuts on pKs and MKs • etag~ 70% (mainly geometrical) • Good determination of KL direction • (s1) and momentum (s1MeV) • Clean KS tag by time of flight identification • of KL interactions in the calorimeter (Kcrash) • KL velocity in f rest frame b*= 0.218 • ecrash  30% (mostly geometrical) • provides a good estimate of KS direction (s1, 0.3 in f) and momentum (s1MeV) Risultati recenti di KLOE

  9. Charged kaons Tagging – 102 Ev/0.5MeV – Kinem. ID  Data — fit: pp0+ mn 3000 + + 2000 1000 K+m+nmK–p–p0 180 200 220 240 Measurement of absolute BR’s: K+ beam tagged from K- p-p0, m-n • Two-body decays identified as peaks • in the momentum spectrum of secondary • tracks in the kaon rest frame: 6•105 tags/pb-1 p*p(MeV) Risultati recenti di KLOE

  10. KLOE results in kaon physics KS Phys. Lett. B538 21 (2002) KS00NEWUpdate with ’01-’02 data sample KSe Phys. Lett. B535 37 (2002) Updated with ’01-’02 data sample KS000Phys. Lett. B 619 61 (2005) KS p+p-p0 In progress K0 mass KLOE Note 181 (http://www.lnf.infn.it/kloe) KLKL30 Phys. Lett. B566 61 (2003) KL, e, +-0, 30 NEW Accepted by Phys. Lett. B KL lifetimeNEWAccepted by Phys. Lett. B Semileptonic form factorsNEWPreliminary results available CP violation & interferenceNEWPreliminary results available Vus fromK+/-  m nPaper in preparation Vus fromK+/-  p l n NEWPreliminary results available K+/-lifetime In progress K+ +00 Phys. Lett. B597 139 (2004) Risultati recenti di KLOE

  11. |Vus f+K0p-(0) |2 I(lt) (1 + DI(lt,a)) (1 + dEM) dSU(2) G(K  pℓn(g))  = 0.5 _ 0.05  |Vus| G I(lt) f+K0p-(0) KLOE is performing a precise measurement of |Vus| i.e. the most precise test of CKM matrix unitarity from 1st row: |Vud|2 + |Vus|2 + |Vub|2~ |Vud|2 + |Vus|2  1 – D Can test if D = 0 at few 10-3: from super-allowed 0+ 0+ Fermi transitions, n b-decays: 2|Vud|dVud = 0.0010 from semileptonic kaon decays (PDG 2002 fit): 2|Vus|dVus = 0.0011 Two techniques: • Extract |Vus| from Kl3 decays. EM effects must be included: d|Vus| dG dI(lt) df+K0p-(0) Relative uncertainty: • Extract |Vus| from(K())/(())ratio. Dominated by the theoreticaluncertainity on thefK/fevaluation. • KLOE can measure all experimental inputs: • BRs, lifetimes, and form factors ! Risultati recenti di KLOE

  12. KL branching ratios using KL beam tagged by KS p+p- 328 pb-1 ’01 + ’02 data 13  106KL’s for counting (75%) 25% used to evaluate efficiencies • BR’s to pen, pmn, and p+p-p0: • KL vertex reconstructed in DC • PID using decay kinematics • Fit with MC spectra including radiative processes and optimized EmC response to m/p/KL • BR to p0p0p0: • Photon vertex reconstructed by TOF using EmC ( 3 clusters) • erec = 99%, background < 1% Data 7% of sample pen pmn p+p-p0 p+p- Lesser of pmiss-Emiss in pm or mp hyp. (MeV) Risultati recenti di KLOE

  13. KLOE results for KL BRs eFV • Errors on absolute BR’s dominated by error on tL • tL needed for geometrical efficiency (eFV) • Alternately, set Sx BR(KL x) = 1 and solve for tL • BR(pen+pmn+p+p-p0 + 3p0) from KLOE + • BR(p+p-+p0p0 + gg) from PDG’04 = 1.0104  0.0076 Obtain: tL/bc BR(KL pen(g)) 0.4007  0.0006  0.0014 800k evts BR(KL pmn(g)) 0.2698  0.0006  0.0014 500k evts BR(KL 3p0) 0.1997  0.0005  0.0019 700k evts BR(KL p+p-p0(g)) 0.1263  0.0005  0.0011 200k evts tL = (50.72  0.17  0.33) ns Risultati recenti di KLOE

  14. Measurement of KL lifetime × 102 • Measure using KL p0p0p0 • Require  3 g’s • e(LK) ~ 99%, uniform in L • Background ~ 1.3% • sL(gg) ~ 2 cm • Use KL p+p-p0 to determine: • EmC time scale • Photon-vertex efficiency • KLOE 400 pb-1 ’01 + ’02 data • 10M KL p0p0p0 evts • tL = 50.92  0.17  0.25 ns • Average with result from KL BR’s: • tL = 50.84  0.23 ns pK = 110 MeV good lever arm for lifetime measurement Events/0.3 ns 6 – 24.8 ns 40 – 165 cm 0.37 lL L/bgc (ns) cf. Vosburgh, ’72: tL = 51.54 ± 0.44 ns Risultati recenti di KLOE

  15. KS semileptonic decay : not only Vus ! AS,L = _ G(KS,L  p-e+n) - G(KS,L  p+e-n) _ G(KS,L  p-e+n) + G(KS,L  p+e-n) CPT in mixing CPT in decay S Q and CPT CP Sensitivity to CPT violating effects through charge asymmetry: AS  AL  0 implies CPT AS= 2(ReK ReK Re b/a Re d*/a) AL = 2(Re K Re K Re b/a Re d*/a) Never measured before ! • G(KSpln) provides also a test of S= Q rule: • GS(pln)/GL(pln) = 1 + 4 Re(x) Risultati recenti di KLOE

  16. KSπ e  selection • Event selection: • KS tagged by KL crash • Two tracks from IP to EmC • Kinematic cuts to reject background from KSpp • Associate tracks to clusters • e/p ID from TOF • Identifies charge of final state • Obtain number of signal events from a constrained likelihood fit of multiple data distributions • Normalize using KSpp events in same data set p+e- Dt-Dtexp(e+p-) (ns) p+e- e+p- e+p- Dt-Dtexp(p+e-) (ns) Risultati recenti di KLOE

  17. Data • MC fit • pen • pp, p  m • ppg • pbadp • ppbad • other PCA2 Evts/MeV 700 Evts/0.2cm 500 PCA1 600 400 500 300 400 300 200 200 100 100 0 0 -150 -100 -50 0 50 -8 -4 0 4 8 Emiss(pe) - pmiss (MeV) dPCA (cm) KSpen event counting Fit distributions of 5 variables in data with various MC sources Close kinematics: Emiss(pe) -pmiss = 0 MC includes peng and ppg processes dPCA = PCA1 – PCA2eliminates p  m kinks and badly reconstructed tracks Risultati recenti di KLOE

  18. BR(p-e+n) = (3.54  0.06  0.04)  10-4 BR(p+e-n) = (3.55  0.05  0.02)  10-4 BR(pen) = (7.09  0.08  0.05)  10-4 BR(KLe3) KLOE KS assuming DS = DQ KTeV ’04 0.40 KLOE ’05 0.39 PDG ’04 KSpen Results • Branching ratios: • 410 pb-1 ’01 + ’02 data • cf. BR(pen) [KLOE ’02, 17 pb-1]: • (6.91  0.34  0.15)  10-4 Charge asymmetry: AS = (-2  9  5)  10-3 dominated by statistics: with 2.5 fb-1: dAS 3 10-3 2 Re e AL = (3.322  0.058  0.047) 10-3 [KTeV 2002] AL = (3.317  0.070  0.072) 10-3 [NA48 2003] Test of DS = DQ rule: t(KS) = 89.62  0.05 ps Avg. KTeV ’03, NA48 ’02 t(KL) = 50.84  0.23 ns KLOE ’05 (avg.) Risultati recenti di KLOE

  19. First observation of KSpmn More difficult: poor charge ID (mm mp), background from KS pp, p  mn • 2002 data • MC m+p-n • MCppg • MCpp Evts/MeV Evts/MeV 3% stat error from fit Cuts on E*(p) + dPCA + rvtx Preselection cuts only: Kinematics and TOF -40 -20 0 20 40 -40 -20 0 20 40 Emiss(pm) -pmiss(MeV) Emiss(pm) -pmiss(MeV) Risultati recenti di KLOE

  20. K nucl.int. Kpp0p0 Kpp0 K± semileptonic decays Events tagged either by K+m2 , K-m2, K+p2 or K-p2 on the opposite side Ev/(14MeV)2 • 1-prong kaon decay vertex in the fiducial volume: rVTX in (40,150) cm • daughter track extrapol. to EMC • Reject two-body decays: • p(mp)  195 MeV • p0 search: 2 neutral clusters in EmC, with ToF matching the K decay vertex (d(dt)<3st) • Spectrum of charged daughter mass, m2lept, from TOF measurement: MC tdecayK = tlept -Llept /(bleptc) = tg-Lg/c • Additional kinematical cuts to reject non-semileptonic decays. • The residual background is about 1.5% of the selected Kl3 sample, and has the mp2 signature. Risultati recenti di KLOE

  21. K±pln signal extraction Ev/(14MeV)2 • Fit m2lept spectrum with a linear combination of Ke3 and Km3 shapes, and background contribution. • Correct MC shapes for Data/MC differences on the calorimeter timing. • The residual distribution show the same trend for all the tag samples. Possible residual different Data-MC resolution. • Selected signal events in 2001/2002 data set Risultati recenti di KLOE

  22. Tag K+m2 Tag K+m2 Tag K+p2 Tag K+p2 Tag K-m2 Tag K-m2 Tag K-p2 Tag K-p2 K±pln preliminary results • The error accounts for the data and Monte Carlo statistics used in the fit, the MC statistics for the efficiency estimation, the Data/MC efficiency corrections, and the systematics on the tag selection. • The systematics due to the signal selection efficiency is under evaluation. • c2/nDof for the 4 measurements: • Ke3: 3.20/3, P(c2> cM2)  36% • Km3: 5.32/3, P(c2> cM2)  15% • taking correlations into account we get: KLOE preliminary • The error is dominated by the error on Data/MC efficiency correction. • Fractional accuracy of 0.9% for Ke3, 1.2% for Km3. Risultati recenti di KLOE

  23. KTeV ISTRA+   KLOE measurements of Vus • Expect from unitarity • Vusf+(0) = 0.2181  0.0022 • Vud = 0.9739  0.0003 • Marciano, CKM ‘05 • Hardy & Towner ‘04 (SFT) • f+(0) = 0.961  0.008 • Leutwyler & Roos • BR’s from KLOE BR(KL e) = 0.4007 0.0015 BR(KL m) = 0.2698 0.0015 • With S BR = 1 constraint • BR(KS e) = (7.09  0.09)  10-4 • BR(K e) = (5.047  0.043)% • BR(K m) = (3.310  0.048)% KL lifetime from KLOE tL = (50.84  0.23) ns Avg. of direct, S BR = 1 determinations • Quadratic form-factor parameterizations: l+ = 0.0221  0.0011 l+= 0.0023  0.0004 l0 = 0.0154  0.0008 prelim. Risultati recenti di KLOE

  24. KLOE Vus and rest of the world Thanks to F. Mescia (see hep-ph/0411097) New Vud t+ = 12.384  0.024 ns [PDG ’04] tL = 50.84  0.23 ns [KLOE] Risultati recenti di KLOE

  25. Particle momentum in K rest frame  Nev/MeV e  MC P*(MeV) Vus from BR(K++()) • Tag from K--; to reduce the tag bias, tag selection requires EMC trigger. • 2002 data set: 1/3 used for signal selection, 2/3 used as efficiency sample • Count events in (225,400) MeV pp* window after the subtraction of p0 identified background. • Selection efficiency measured on data. • Radiated g acceptance measured on MC. BR(K+m+n(g)) = 0.6366  0.0009stat. 0.0015syst. • Following Marciano hep-ph/0406324 : • (K())/(())  |Vus|2/|Vud|2fK2/f2 • From lattice calculations: fK /f=1.210±0.014 (MILC Coll. hep-lat/0407028) • Vud=0.9740±0.0005 (superallowed -decays) Vus = 0.2223±0.0025KLOE preliminary Risultati recenti di KLOE

  26. Ke3 • phase space • phase space + FF KLe3 form-factor slopes • Form-factor slopes for K pln decays needed for extraction of Vus (evaluation of phase-space integrals) • Parameterization: • t = (pK-pp)2/m2p+ • For Ke3:f+(t) = f+(0) [1 +l+t] or • f+(0) [1 +l+t+ ½ l+t2] Ed Blucher dN/dt • Preliminary KLOE results for KL pen decays: • 328 pb-1 of ’01 + ’02 data • KL decays tagged by KS p+p- satisfying trigger (e  30%) • Two tracks in fiducial volume forming vertex • Kinematic cuts + TOF PID to reduce background • Separate mmts for each charge state (e+p-, p+e-) to check systematics t Risultati recenti di KLOE

  27. KLe3 form-factor slopes KLOE preliminary 328 pb-1’01 + ’02 data, 2  106Ke3 decays • Linear fit: • l+10-3c2/dof • e+p- 28.7  0.7 156/181 • p+e- 28.5  0.6 174/181 • All 28.6  0.5 330/363 • l+ = (28.6  0.5  0.8)  10-3 • Quadratic fit: • l+10-3l+10-3c2/dof • e+p- 24.6  2.1 1.9  1.0 152/180 • p+e- 26.4  2.1 1.0  1.0 173/180 • All 25.5  1.5 1.4  0.7 325/362 • l+ = (25.5  1.5  1.9)  10-3 • l+ = (1.4  0.7  0.7)  10-3 • r(l+, l+) = -0.95 1s contours l+10-3 KTeV ISTRA+ KLOE NA48 l+10-3 Risultati recenti di KLOE

  28. Rare decays @KLOE: search for KSp0p0p0 c22p • KS  3p0is purelyCP violating • If CPT conserved, GS= GL|e+e000|2 • BR(KS  3p0) = 1.9 × 10-9 • Best previous result from direct search: • BR < 1.4 × 10-5 90% CL [SND ’99] • Signature (epresel ~ 14%): • KL crash + 6 g’s, no tracks from IP • Background rejection: • KS  p0p0 + 2split/accidental clusters • Define signal box in c23p vs. c22p plane: • c23p3 cluster pairs with best p0 mass estimates • c22p2 best cluster pairs - p0 masses, E(KS), p(KS), angle between p0’s • MC 3p (BR 10-5) • MC 2p c23p Risultati recenti di KLOE

  29. KSp0p0p0: Results and prospects c22p MC Eff. Stat. = 5.3 data • Nbkg(MC) = 3.13  0.82  0.37 • Nobs = 2 • KLOE 450 pb-1 ’01+’02 data • BR  1.2 × 10-7 90% CL • cf. NA48 ’05 (interference) • BR  7.4 × 10-7 90% CL • Prospects for 2 fb-1: • 6.5 increase in statistics • (L efficiency) • 1.5 decrease in background • Potential to reduce limit ~10 c23p c22p 450 pb-1 ’01+’02 data c23p Risultati recenti di KLOE

  30. c2 from kinematic fit: • MC background • MC signal (L× ~100) Search for KSp+p-p0 • Decaymainly CP-conserving (DI = 3/2) • BR useful to constrain K 3p amplitudes • PDG ’04: BR = (3.2+1.2-1.0)  10-7 • Based on interference measurements • [CPLEAR, E621] New NA48 preliminary • Never observed directly • First use of ’04 data: 740 pb-1 total! • Preselection criteria (e = 7%) • KL crash + vertex + 2 g clusters • Kinematic fit rejects > 99% of bkg • 6 constraints + m(p0) + m(KS) • Remaining backgrounds: • f K+K-Cut on momentum of secondaries at ends of p tracks • KS p0Dp0(D) Associate tracks to clusters, get e/p ID from TOF • Both types Veto on extraneous prompt clusters Risultati recenti di KLOE

  31. KSp+p-p0: Current status • Preliminary results with 740 pb-1 ’01 + ’02 + ’04 data: • Signal efficiency: ~ 1.5% (including KL-crash eff) • Candidates: 6 events • Background (sidebands): ~ 3.5 events • Number of events observed consistent with expectation • Statistical error: ~ 100% • Evaluation of systematic error in progress • Scaling these values to 2 fb-1 we expect: • Measurement of BR(KS  p+p-p0) with 60% error • About the same precision as interference-based measurements • First measurement of BR from a direct search Risultati recenti di KLOE

  32. KLOE results in “non-kaon” physics continuum: • (ee→hadrons)Phys. Lett. B606, 12 (2005) (small angle g) • Large photon angle analysis in progress f decays: • f  p+p-p0Phys. Lett. B561 55 (2003) •  f0g ,a0gPhys. Lett. B536 209 (2002), B537 21 (2002) update with 2001/02 statistics almost final f0π+π-channel studied (g at large angles) •  ggg Phys. Lett. B591 49 (2004) h  π+π-New limit available • →p+p-p0 , p0p0p0 preliminaryDalitz plot analysis • p0gg preliminary result available •  h´gPhys. Lett. B541 45 (2002) update with 2001/02 data in progress Risultati recenti di KLOE

  33. g gKK gSKK gSP1P2 K+ P1 f S P2 K- Light scalar mesons • e+e-   f0(980); f0(980)(I=0) 00 +-  +-  final state • 5  final state • e+e-   a0(980); a0(980) (I=1)  0 •  • +-0  +- + 5  final state • not easily interpreted as mesons (3P0 nonet) • other interpretations: states (Jaffe ’77) • molecules (Weinstein-Isgur ’90) • Fit the mass spectra or the Dalitz plot to extract the relevant parameters • (masses, couplings, ...): two models exploited • 1) “No Structure” – S as simple BW 2) Kaon Loop • [Isidori-Maiani, private communication][Achasov-Ivanchenko, NPB315 (1989) 465] P1 S e+ e+ gS gSP1P2  P2 e- e- g Risultati recenti di KLOE

  34. f0(980) region Events/1.2 MeV M(pp) (MeV) M(pp) (MeV) f0(980)+- • f0 Already observed in p0p0 final state • e+e-+- events with the photon at large angle (45<<135) • Main contributions: ISR (radiative return to ,   pion FF ), FSR • Look for deviations on Mππ spectrum from the expected ISR+FSR behaviour • Data sample: 350 pb-1 at  peak , 676000 events selected • Kaon loop model fits better F-B asymmetry Asymmetry 800 M(pp) (MeV) 600 Risultati recenti di KLOE

  35. A by product analysis: hp+p-upper limit P and CP violating decay Standard Model prediction BR ~ 10-27 10-24 e=16.6% Normalization to h->3p0 BR < 1.3 10-5 @90% C.L. Risultati recenti di KLOE

  36. h and h’ at KLOE • h/ h produced through M1 transition f→Pg • Erecoil(h) = 363 MeV very clean h sample • Erecoil(h) = 60 MeV grecoil misid. for some channels… f  hg Monochromaticrecoil photon very powerful for event id ! f hg Eg (MeV) • f  h g p+p-p0g  p+p-ggg • f  hg  h p+p-g  ggp+p-g Risultati recenti di KLOE

  37. N = 3405  61  28 evts. N = 1.7  106 evts. inv.mass of +-+ 6 out of 7 inv.mass of +-+ 6 out of 7 syst. dominated by the uncertainties on Br(+-) and Br(00) We will measure them with 2 fb-1 KLOE Preliminary • data • MC R= 4.7  0.5  0.3 KLOE [Phys.Lett.B541(2002)] ( +-+3 final state, 17pb-1 of 2000 data)  mixing angle By using the PDG value of Br()  Br() = (6.16  0.20  0.28)  10-5 M6 (MeV) M6 (MeV) BR()/BR() • ;   +-; 000 •  00; +- 0 • ; 000 +- + 7  final state Risultati recenti di KLOE

  38. background estimate from the sidebands Erecoil = 363 MeV  4  expected signal shape Search for h  ggg Violates C, BR < 5104 @95% CL PDG ’02 (GAMS2000) BR(31.6105 @ 90% CL Phys. Lett. B (591) pp. 49-54 (2004) Risultati recenti di KLOE

  39. M4 (MeV) A clean test of chiral PT: 0 • PT: relevant terms start at O(p6) • Recent measurements of Br(0): (7.21.4)10-4 GAMS (1984) • < 8.4 10-4@90% C.L. SND (2001) • (2.70.90.5)10-4 Crystal Ball (2004) • ; 0  5  final state • Large background from: (1) 5 processes: a0, f0; e+e-0 (0) • (2) ; 000 with lost or merged photons • Reject (1) with veto on , , and additional 0 • Reduce (2) by exploiting shower shape variables • to identify merged clusters • Fit to the 4 inv. mass spectrum: 735 evts selected  Sign. = 68  23; Bkg=667  36 KLOE Preliminary BR(h→p0gg) = ( 8.4 ± 2.7stat±1.4syst ) × 10-5 Risultati recenti di KLOE

  40. [1] [2] [3] [4] [5] [6] [7] [8] GAMS (1984) KLOE 1s KLOE 2s Crystal Ball (2004) KLOE 3s O(p6) calculations KLOE 0 • Factor ~ 10 less than GAMS • Only marginally compatible with Crystal Ball • Good agreement with O(p6) calculations Risultati recenti di KLOE

  41. Conclusioni La f-factory DAFNE fornisce un ambiente sperimentale unico al mondo, dove si possono selezionare grandi campioni di mesoni K con un purezza ed un controllo delle sistematiche eccellenti. KLOE sta producendo una serie di importanti misure in fisica del K ed in fisica adronica, spesso migliorando di ordine di grandezza la precisione delle misure precedenti. Attualmente KLOE sta raccogliendo un campione di dati di dimensione almeno 4 volte superiore a quello sinora analizzato: ci aspettiamo notevoli miglioramenti delle misure già effettuate, e sensibilità a canali più rari ! IL PESO DELLA SCIENZA Risultati recenti di KLOE

  42. SPARE SLIDES Risultati recenti di KLOE

  43. BR(KSp+p-(g))/BR(KSp0p0) • Interest in KS pp branching ratios: • Rpp fixes BR(KS p+p-(g)), used to normalize BR(KS pen) • Opportunity to push systematics for high-precision KLOE measurements • First part of double ratio for Re e/e • Provides information on EM isospin breaking in K pp decays • Can extract d0- d2 if effective Eg cutoff known for ppg channel • Previous mmt: KLOE ’02 17 pb-1 ’00 data 2.236 0.003  0.015 • Repeat analysis with various improvements: • New simulation of machine background in MC • Reproduces effects e.g. on selection efficiency on a run-by-run basis • Improved KL-crash simulation • Leads to optimized choice of KL-crash energy cut: 100  200 MeV • Higher statistics allow stability of result to be studied Risultati recenti di KLOE

  44. Rpp vs. running period 2.256 ± 0.003 2/dof = 0.99 (45.9%) 2001 2.259  0.004 2002 2.254  0.003 BR(KSp+p-(g))/BR(KSp0p0) KLOE ’02 17 pb-1 ’00 data2.236 0.003  0.015 KLOE ’05 preliminary 410 pb-1 ’01 + ’02 data 2.256 0.003  0.010 Risultati recenti di KLOE

  45. Event counting checks Data-MC agreement after the fit is satisfactory Reliability of the fit result has been checked on variables not used in the fit PID from spatial distribution of energy deposit in EmC is a valuable tool  Data — MC fit signal  pm  ppg  pbadp  ppbad other  Data — MC fit signal  pm  ppg  pbadp  ppbad other 500 200 Evts/2.5MeV Evts/0.1 150 300 100 50 100 0 0 1 400 500 -2 -1 0 300 350 450 Mpp(MeV) Ln(Le)/Ln(max{Lp,Lm}) Risultati recenti di KLOE

  46. Analysis outline – efficiency estimate Two methods for the efficiency estimate: • “Single-particle” method: • Estimate single-particle efficiencies from various sources, both in data and MC • Parametrize as a function of kinematical variables: Pt, Pz, P, cos a, zfib • Use Data/MC efficiency ratio to correct MC efficiencies • “Double-particle” method: • Select prompt KL  pen decays, accompanied by KS  pp • Evaluate the efficiency on the control sample, with attention to the trigger condition in each event Comparison of two methods used to evaluate systematic uncertainty Total efficiency is 20% given the tag Risultati recenti di KLOE

  47. Systematic uncertainties Dependence of corrections on charge state is crucial for the charge asymmetry TOF efficiency responsible for the charge dependence: de/e = (4.3 ± 0.9stat± 0.8syst)% TOF difference arise from different hadronic interaction mechanisms for p+ and p- in EmC Corrections studied as a function of time during data taking: the result is stable Check fit stability and MC reliability by varying KL crash minimum energy Risultati recenti di KLOE

  48. KSpen decays – Results Compare G(KS  pen) with G(KL  pen): test of the DS = DQ rule Use average of KTeV and NA48 measurements of KS lifetime: tS = (89.62  0.05) ps Use new measurement of the KL lifetime: tL = (50.81  0.23) ns [KLOE 05] Re(x) =1/4 [G(KS  pen) / G(KL  pen) - 1] KLOE KS assuming DS=DQ BR KLe3 0.41 Use BR(KL  pen) = (40.67 ± 0.11)% [KTeV 04]: Re(x) = (-3.1  3.0stat  1.8syst) 10-3 Use BR(KL  pen) = (40.07 ± 0.17)% [KLOE 05*]: Re(x) = (+0.6  3.1stat  1.8syst) 10-3 KTeV 04 0.40 KLOE 05* Most precise measurement of Re(x) (in CPT conserving transitions): compare w CPLEAR99, dRe(x) = 6×10-3 0.39 PDG04 0.38 *to be published, see C. Bloise talk in this conference Risultati recenti di KLOE

  49. Charged kaon lifetime - 1 • Vus experimental input. • 0.2% fractional accuracy; 0.1% for Vus. • Affects the BR measurement via the geometrical acceptance. • t PDG entries: discrepancies between in-flight and at-rest measurements; discrepancies between different stoppers in at-rest measurements. • New high statistics t measurement almost complete at KLOE, now under the review of the collaboration. • Two different methods to measure t. • Measuring K decay length • Measuring K decay time • Cross check on the systematic error. Risultati recenti di KLOE

  50. Tag(Km2) Charged kaon lifetime - 2 • Common to both methods: • Tag events with Km2 decay • Identify a kaon decay vertex in DC fiducial volume • 1st method: • Measure the kaon decay length taking into account the energy loss: tK = i Li/(bigic) • Tracking efficiency and resolution measured on data by means of neutral vertex identification. • Fit of the tK distribution. • 0.2% fractional error. • 2nd method: • Use only Kp2 decays • Use tag information to estimate the T0 i.e. the fK+K time. • Identify the clusters belonging to p0. • Measure the kaon decay time: • tK = (tg – Rg/c –T0)gK. • gK: average over the kaon path (0.5% fractional error on tK) Risultati recenti di KLOE

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