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Status of the Measurement of the f meson parameters

Status of the Measurement of the f meson parameters. KLOE General meeting 19-12-2002. M. Dreucci for f fitter WG. M. Antonelli, C. Bini, F. Bossi, P. Branchini, M. Dreucci, C. Gatti, S. Giovannella, S. Miscetti, M. Palutan, L. Passalacqua, B. Sciascia, T. Spadaro. Introduction.

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Status of the Measurement of the f meson parameters

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  1. Status of the Measurement of the f meson parameters KLOE General meeting 19-12-2002 M. Dreucci for ffitter WG M. Antonelli, C. Bini, F. Bossi, P. Branchini, M. Dreucci, C. Gatti, S. Giovannella, S. Miscetti, M. Palutan, L. Passalacqua, B. Sciascia, T. Spadaro

  2. Introduction • theoretical cross sections • data samples and MC simulation • measurement of DAfNE parameters • status of cross section measurements • status of lineshape fits • measurement of leptonic widths • conclusions

  3. Cross sections Born f cross section: Main decays modes K+K– 49.2% KLKS 33.7%  15.5%  1.3% + corrections (phase space + contributions from w r ) f parameters: mass, total width, peak cross sections leptonic modes e+e– 3.0 x 10-3 m+m– 2.9 x 10-3 Peak cross section the measurement of the partial widths requires the knowledge of e+e- width(no direct measurement available)

  4. Cross sections 2 Born f cross sections including contributions from w, rexchange* Up to 10% effects • , r parameters can be fixed to PDG values with no loss of accuracy in measuring the f parameters Born f cross sections (mb) K+K– KLKS   W(MeV) *[ N.N. Achasov et. al. Yad. Fiz. 54, 1097 (1991)]

  5. Initial state radiation correction Standard method: Radiator sth Radiator from Nicrosini et al. 2ndDAFNE handbook numerical integration with VEGAS Kuraev-Fadin radiator used for comparison (no differences) other integration codes used: REMT + home developed one

  6. Initial state radiation correction KLKS • up to 30% correction W (MeV)

  7. KL g KS Data samples and MC simulation data sample 2001 scan: 0.5 pb-1 W[1015:1025] 11 points ~50 nb-1 each 2002: 2 high statistics (7+8 pb-1) energy points @ mfGf/2 + ~ 7 pb-1 at peak MC simulation W=1025 MeV Careful treatment of ISR effects in the generator radiative returns to fmeson KS-KL invariant mass (MeV/c2) s(s) + H(s,s’) + beam energy spread + radiation from both beams

  8. Measurement of DAfNE parameters Luminosity: from large angle bhabha at % level corrected for sbhabha(W) center-of-mass energy beam energy spread e+e- invariant mass (MeV/c2) absolute calibration @ ~2x10-4 linearity @ ~ 10-5 using redondat W measurement in KS->p+p- KL crash events

  9. Status of cross section measurements All analyses well advanced: refinements in progress expected accuracies at % level for each channel K+K–selection Use event symmetry K->pp0 double tag method single tag Double tag Track momentum in Kaon rest frame (MeV)

  10. KLKS selection Based on KL crash algorithm absolute KL crash efficiency from KS->p0p0 KL side not biased Polar angle distribution not altered

  11.  selection Missing mass from measured momenta + W Selection based on kinematics cos (g g angle) in p0 rest frame Mp0 from g g

  12.  selection Very clear signatures agreement within different channels ->3p0, ->gg

  13. Preliminary measurements s(nb)

  14. Preliminary lineshape fits Results of 4 independent fits Direct term in  set to 0 BeS overestimated? (default 575 KeV)

  15. Status of lineshape fits: rp s(nb) W(MeV)

  16. Status of lineshape fits 2 Good agrement in Mf , Gf values for K+K–, KLKS ,  problems in fitting  ( add direct terms) But efficiency vs effective W’/W cut not evaluated Radiative return to w W’(MeV)

  17. Status of lineshape fits 3 Combined fit: rp not included fit with rp in + direct term tried….

  18. Status of lineshape fits: K+K- s(nb) W(MeV)

  19. Status of lineshape fits: KSKL s(nb) W(MeV)

  20. Status of lineshape fits 4: g s(nb) W(MeV)

  21. Sensitivity to new physics? Light + strong coupling objects ( Axions, g ) ~ Measurement of Gee Necessary for the mesurement of partial width measurement Gfinvisible Check of Contribution to e+e- e+e- process

  22. e+e- e+e- forward backward asymmetry • AFB : enhanced sensitivity to Gee with respect to see sensitivity to Gee AFB Some experimental advantages: • Luminosity not needed • Partial cancellations (eff, bkg, syst.) W (MeV)

  23. Preliminary results: full data sample AFB AFB relative accuracy at 8x10-5 Gee at ~2.3% Still to do: more MC Systematics Gee = 1.30 0.03 keV W (MeV)

  24. Perspective for the measurement of Gmm Check consistency with Gee (just QED) Combine the two measurements smm (nb) Expected accuracy on Gmm measurement ~ 1.5% W (MeV)

  25. Conclusions The status of the analyses of the f lineshape in different chennels is well advanced: First preliminary results for all channels Mf and Gf in agreement within channels but for rp Gf seems to be too small (investigate on BeS) charged kaon cross section ~18% higher wrt SND Gee at 2.3% value in agreement with PDG ( Gmm came soon ) We have just started…..

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