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Ilaria Villella I.N.F.N. and Universita’ di Napoli

3 rd KLOE Physics Workshop May 24th 2003, Capri. Status Report on fhgp + p - gg. Ilaria Villella I.N.F.N. and Universita’ di Napoli. Study of h  p + p - g. BR measurement( h  p + p - g ) PDG’02: BR( h  p + p - g ) = (4.68±0.11)x10 -2 Study of theoretical model :

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Ilaria Villella I.N.F.N. and Universita’ di Napoli

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  1. 3rd KLOE Physics Workshop May24th2003, Capri Status Report on fhgp+p-gg Ilaria Villella I.N.F.N. and Universita’ di Napoli

  2. Study of hp+p-g • BRmeasurement(h p+p-g) PDG’02: BR(h p+p-g) = (4.68±0.11)x10-2 • Study of theoretical model : comparison of the predicted spectra whit the corresponding experimentally determined values ¤ In MC generator (Gormley et al. P.R.D2(1970),501 7250 events) • There is a model including the effect of a pp final-state interaction assuming that the dipion phase shift is dominated by the r meson; May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  3. Theoretical Models Anomalous contribution: Contribution of the box anomaly beside the classical triangle anomaly responsible for h/h’p+p-g decays predicted by PCAC and by the Wess-Zumino-Witten chiral lagrangian. Resonant contribution: • Model M2: involving the r whit its subsequent decay to a pion pair (VDM); • Model M1: existence of a small non-VDMcontribution; The anomalous and resonat contribution are indipendent processes. May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  4. Signal and Background • s(mb) • Signal decay • fhgp+p-gg1.84 x10-3 • Background decay S/B • f p+p-p0p+p-gg 0.44 4 x 10-3 • e+e-wp0p+p-gg 7.66x10-6 2.4 x 102 • fhgp+p-p0g 8.717x10-3 0.2 May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  5. Signal: hp+p-g Final State: p+ p- g g Topological cut: • 2 prompt photons |tcl-lcl/c| < 5 st; • 1 charged vertex with two associated tracks • The Vertex must be inside the following region: rxy < 4 cm; |z|< 8 cm. Kinematic fit without mass constraint. Filfo EVCL(RADstream) topological cut Total eselection: 99% 54%86% 46 % May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  6. RPI stream efficiency eRPIstre eRPI= 11.50% Eg(Mev) RAD stream efficiency eRADstream Eg(Mev) gh spectrum Eg(Mev) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  7. Invariant mass of two photons MCtrue MC true RAD Stream MC true RPI Stream Mgg (MeV) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  8. RAD+RPI Stream Efficiency Average e = 66% Eg(Mev) Eg(Mev) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  9. (Ep++Ep-)h(MeV) (Eg)h(Mev) Ep++Ep- (MeV) RPI Stream cuts SIGNAL h rest frame • f rest frame: (Egrad)f =363 Mev; ph = pf–pg • ph in lab. Frame • Boost p+ p- gh in h rest frame May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  10. RPI Stream cuts Background (Ep++Ep-)h(MeV) Ep++Ep- (MeV) (Eg)h(Mev) • Signal Background • =Ncuts/NRPI 80.7%17.8% (S/B)RPI =3x10-3 May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  11. RAD+RPI stream S/B=2x10-2 S S+B Egh (MeV) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  12. Cuts • Both streams: • P(c2)>10-4 • 357.8 MeV< Egrad <368.2 MeV S/B =0.14 Signal Background Egrad(MeV) Egrad(MeV) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  13. fppp signal Bhabha Tight cuts Only RAD stream: • P(c2)>10-4 • 357.8MeV<Egrad<368.2MeV S/B = 1.63 Lint= 29 pb-1 2001 datarecV13 Recoil mass(MeV) Recoil mass > 160 MeV S/B = 4.59x 102 May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  14. h Invariant Mass RAD stream Lint= 29 pb-1 Mppg(MeV) 357.8MeV<Egrad<368.2MeV Recoil mass > 160 MeV Mppg(MeV) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  15. Branching Ratio Accuracy We select N=18508 events our BR 3% below PDG’02 value sBR/BR = 7 x 10-3 preliminary cosqpp There is still background Mppg(MeV) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  16. Conclusions and Outlook • We will study cuts based on angular variable • to reduce other background, but we need MC events from the last GEANFI version • (some bugs resolved). • We plan to analyse 100pb-1 • Faisability to check different theoretical model for hp+p-g decay May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  17. May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  18. KLOE: 500pb-1  4.6x105 events (eselection~50%) Trackmass s = E p+ +E p- + Eg Trackmass(MeV) May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  19. Angular distribution Expected angular distribution  dN/d(cosq)~sin2q cosq Corrected MC generator is now in geanfi May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  20. May 24th 2003 - 3rd KLOE Physics Workshop, Capri

  21. May 24th 2003 - 3rd KLOE Physics Workshop, Capri

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