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Hadronic results from KLOE

European Physical Society International Europhysics Conference on High Energy Physics EPS (July 17th-23rd 2003) in Aachen, Germany. Hadronic results from KLOE. E. Santovetti (INFN – Roma II) for the KLOE Collaboration. DA F NE: the Frascati F factory.

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Hadronic results from KLOE

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  1. European Physical Society International Europhysics Conference on High Energy Physics EPS (July 17th-23rd 2003) in Aachen, Germany Hadronic results from KLOE E. Santovetti (INFN – Roma II) for the KLOE Collaboration

  2. DAFNE: the Frascati F factory • electron positron collider at the f mass energy (ECM= 1020 MeV) • separate rings to minimize beam-beam interaction • two interaction points (KLOE – DEAR/FINUDA) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  3. KLOE data taking history in 2002 An upgrade of the machine has been done. An increase in luminosity ( > x2 ) is expected in the next data taking. E. Santovetti HEP2003 Aachen, 17-23 July 2003

  4. KL e- e+ f KS Kaon physics at DAFNE • The kaons are produced in pairs (K+ K- and KS KL ) with opposite momentum. • The detection of a kaon on one side can be used to tag the other kaon in the opposite side • Measure of absolute branching ratios • Interferometry studies on KS KL system all KS decay close to the IP reasonable acceptance for KL E. Santovetti HEP2003 Aachen, 17-23 July 2003

  5. The KLOE detector • Electromagnetic calorimeter • lead/scintillating fibers structure • 15 X0 thickness • 4880 PMT's • Drift chamber (4m Ø x 3.3m) • 90% He – 10% IsoB mixture (X0 ~ 500m) • 12582/52140 sense/total wires • stereo geometry for z measurement • Quadrupole calorimeter • lead/sc. tiles calorimeter surrounding the permanent quadrupoles (32 PMT's) • Superconducting coil (5m Ø) • B = 0.52 T E. Santovetti HEP2003 Aachen, 17-23 July 2003

  6. High efficiency for low energy photons Detector performances calorimeter Drift chamber E. Santovetti HEP2003 Aachen, 17-23 July 2003

  7. Discrete symmetries • Re(e/e) via double ratio (CP direct) • KLKS Semileptonic asymmetry (CPT) • KLKS interferometry 2 fb–1 • KS gg , KS3p, KSppg • KL 2p, KL gg • Vus from K± and KL decays • K± branching ratios • s(e+e– p+p–) to 1% 200 pb–1 2000 2002 20 pb–1 • f radiative decays f f0g , a0g scalar f  h’g , hg pseudoscalar • KS decays BR(KS p+p–)/BR(KS p0p0) BR(KS pen) first published results 2 pb–1 KLOE physics program 1999 500 pb-1 now on tape E. Santovetti HEP2003 Aachen, 17-23 July 2003

  8. K+K– KSKL rp In the case of  a fit with several points has been used to find the correct line shape form (interference between direct,  and w) hg f mass and width + corrections (phase space + contributions from w r ) f line shape has been fitted for the main f decays K+K– 49.2% KLKS 33.7%  15.5%  1.3% f parameters: mass, total width, peak cross sections With a combined fit, we measure the f width: Gf=4.19±0.04 MeV (preliminary) (Mass is calibrated with the CMD-2 value) W(MeV) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  9. MKs=497.583±0.005stat±0.020syst MeV* PDG: 497.648±0.022 MeV 2001 Energy scan *KLOE Note 181 (http://www.lnf.infn.it/kloe/) Neutral kaon mass KLOE can study masses of particles with high accuracy thanks to excellent drift chamber momentum resolution Neutral kaon mass can be measured using KSgp+p- Energy scale from CMD-2 f mass value fgKSKL KSgp+p- s(e+e-gKSKL) (mb) W (MeV) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  10. KS is tagged by identification of KL in the calorimeter (KL crash): a neutral cluster in a fixed time window • efficiency ~ 30% ( largely geometrical) • angular resolution on tagged KS ~ 1° • momentum resolution ~ 2 MeV • KL is tagged by identification of the • KSgp+ p- decay: a vertex near the interaction point with the kaon inv. mass • efficiency ~ 70% • angular resolution on tagged KL ~ 1° • momentum resolution ~ 2 MeV KS/KL tagging E. Santovetti HEP2003 Aachen, 17-23 July 2003

  11. From the K g pp decays (KS, K+), in the exact isospin symmetry hypothesis, we have: considering the EM correction: Kgpp decays measure c0-c2 To extract d0-d2, we need a theoretical input dEM. Important to know the effective Eg cutoff in p+ p- g decay G(KSgp+p-(g))/G(KSgp0p0) • Can be used to extract d0-d2 phase shifts and Kgpp amplitudes • Provides information on isospin symmetry breaking from EM terms Chiral pert. theory • First part of the double ratio E. Santovetti HEP2003 Aachen, 17-23 July 2003

  12. MC  MC  G(KSgp+p-(g))/G(KSgp0p0) • KSgp0p0 • at least 3 neutral clusters in time • Ecl> 20 MeV, |cosq| < 0.9 • to reduce machine Bkg • Efficiency ~ 90% • KSgp+p- • 2 tracks from IP extrapolated to the EmC (120 MeV <pTRK < 300 MeV) Efficiency ~ 60% The measurement is fully inclusive in the radiated photon energy (no cut in the p+p- invariant mass) Efficiency is corrected for the radiated photon in the final state by folding the MC distribution (linear interpolation) with the photon spectrum theoretically predicted 0.3% effect E. Santovetti HEP2003 Aachen, 17-23 July 2003

  13. *Cirigliano et al. (2000) **G. Colangelo et al. (2001) KLOE ‘02 G(KSgp+p-(g))/G(KSgp0p0) Physics Letters B538 (2002) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  14. Cut on time of flight: The mass hypothesis m=me and m=mp on both tracks allows to discriminate a large part of background KSgp-e+n, p+e-n Together with the KLgpen, can be used to strictly test CPT and the DS=DQ Provides information about Vus • Difficoult to isolate Ksgpen respect to the more abundant (x1000) Ksgpp • best measurement CMD-2: BR(Ksgpen) = (7.2 ± 1.4) x 10-4 (75 events) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  15. CMD-2 ’99 PDG eval. from KL KLOE ’02* (17 pb-1 2000 data) *Physics Letters B535 (2002) KLOE ’03 preliminary 6 7 8 ×10-4 KSgp-e+n, p+e-n Use of variable Emiss-cpmiss For pen decays this is the neutrino mass, while for the p+p- decays a value larger than zero is expected. A fit of the data to the sum of the signal and background spectra simulated by MonteCarlo allows to extract the number of events. E. Santovetti HEP2003 Aachen, 17-23 July 2003

  16. DSDQ transitions are forbidden at lowest order in the SM DS=DQ: c = d = Re(x) = 0 K0gpen, CPT and DS=DQ CPT:b = d = 0 AS = AL if CPT conserved KLOE preliminary AS = (19 ± 17stat ± 6syst) x 10-3 First measurment of AS ! E. Santovetti HEP2003 Aachen, 17-23 July 2003

  17. gg invariant mass plot after the cut on collinearity and total energy tL (ns) KLOE 51.5 ± 0.4 PDG '02 51.7 ± 0.4 Preliminary 1/10 of 362 pb-1 362 pb-1 of data analysed ('01+'02 data) KLgp0p0p0 G(KLggg)/G(KLgp0p0p0) • Provide information about the absortive contribution (Aabs) to the KLgmm decay (long-distance term) – Prediction on Ksggg • Very sensitive to the calorimeter performance in reconstructing the neutral vertex • very clean signals: low background (KLgp0p0) • KLgp0p0p0 • inclusive measure: at least four neutral clusters in time with Eg > 20 MeV • Efficiency > 99% • Background ~ 0.4% (KLgp0p0) • KLggg • Close kynematics: cuts on • - E*tot, Collinearity, Invariant mass • Efficiency ~ 80% • Background negligible *Physics Letters B? (2003) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  18. pmn pen p+p- p+p-p0 Pmiss - Emiss in pmor mphyp. (MeV) KLg charged (very preliminary) *Errors are statistical only! (including MC statistics) Systematic errors also ~1-2% but not yet fully evaluated Very preliminary 78 pb-1 ’02 data E. Santovetti HEP2003 Aachen, 17-23 July 2003

  19.  0 + K+  – K– 0 0    K±gpp0p0 (t') • Direct CP violation in the charge asimmetry (from theory 10-6 ÷ 10-4) • Dalitz plot parameters (CP) • Extract isospin amplitudes and phase shifts for Kgppp decay (cPT) (t') best value (PDG '02) has ~2% error and concerns only K+ • Selection • mn/pp0– tagging and self-triggering • 2-tracks vtx in DC volume • p* < 135 MeV/c • 4 clusters ontime @ vtx(Dt<4s) • Etot < 450 MeV Background: main K± decays, Ke4’ Efficiencies evaluated from data by using control samples (ex. ecl from K±gpp0) E. Santovetti HEP2003 Aachen, 17-23 July 2003

  20. 187 pb-1 event counting (~80000 ev.) 250 pb-1 efficiency estimate K±gpp0p0 (t') *KLOE Note 187 Preliminary Dalitz plot analysis: F(X,Y) = 1+gY+hY2+kX2 si=(PK–Pi)2 s0=isi/3 ; X=(s1–s2)/m2 Y=(s3–s0)/m2 Charge asimmetry analysis in progress E. Santovetti HEP2003 Aachen, 17-23 July 2003

  21. For Ke3 modes: E865 preliminary exp th KLOE preliminary BR’s confirm previous values for K0e3, K0m3 KLOE will have BR(K+e3) soon KLOE will measure all BR’s to < 1% and can also significantly improve l+, l0, tL Vus determination Introduced in 1963, known to 1.5% |Vus| = 0.2196 ± 0.0019exp ± 0.0018th tL = (5.17 ± 0.04) · 10-8 s tS = (8.9598 ± 0.0007) · 10-11 s t+ = (1.2384 ± 0.0024) · 10-8 s E. Santovetti HEP2003 Aachen, 17-23 July 2003

  22. f grp,p+p-p0 DaFne produces 5·105p+p-p0 events/pb-1 ,allowing a detailed study of the decay dominated by the rp intermediate state: r mass measurement (CPT) • Selection • 2 charged tracks with vtx at I.P. • |Mmiss– Mp°| < 20 MeV (p0 mass) • 2 photons (cos q*gg< –0.98) (collinearity) • c2 = (Etot- Mf)2/sE2 + (Mgg-Mp°)2/sM2 < 8 Efficiency ~ 30% - Negligible background Fit of the Dalitz plot considering a direct decay together with rp (dominant) and wp intermediate staes: Arp : 3 terms : Mr+, Mr–,Mr0 and Gr (Gounaris Sakurai shape) Awp : standard Breit Wigner Adir: constant  ad eifd : |ad|2 =  |Adir|2 /  |Arp|2 E. Santovetti HEP2003 Aachen, 17-23 July 2003

  23. f grp,p+p-p0 2×106 events analyzed (16 pb–1 – 2000 data) Very different values depending on the used techniques: e+e-, t decay, hadronproduction X=(E+– E–)/3 Y=(E°– M°) *Physics Letters B561 (2003) Relative decay intensities from integration of |A|2 over Dalitz plot Irp = 0.937 Idir = 0.0085 Iwp = 0.0002 Irp + Idir + Iwp  1 (+6%) Interference between rp and direct decays E. Santovetti HEP2003 Aachen, 17-23 July 2003

  24. Conclusions and outlook • DANE luminosity has been continuously improving. KLOE expects to collect at least 1 fb-1 in 2003/2004 • Analysis of 2000-2001 data brought to several published results on neutral kaons and  decays • Work in progress with 2001/2002 data: - K , KLsemileptonic decays (Vus) – Rare kaons decays: KS  p+p-g, KS  3p0, KS  p+p- e+e,KS  gg –  decays (about 2×107 produced in 500 pb-1) E. Santovetti HEP2003 Aachen, 17-23 July 2003

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