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Status of f 0 (980)  p + p - analysis

LNF 03/02/05. Status of f 0 (980)  p + p - analysis. Study of background sources ( m + m - g , p + p - p 0 , p + p - ) r 0 line shape and r 0 - w interference Three different fits to the same spectrum Charge asymmetry. Muon MC. Muon data. Pions data-MC. 1.Study of background sources

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Status of f 0 (980)  p + p - analysis

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  1. LNF 03/02/05 Status of f0(980)p+p-analysis • Study of background sources (m+m-g,p+p-p0,p+p-) • r0 line shape and r0-w interference • Three different fits to the same spectrum • Charge asymmetry

  2. Muon MC Muon data Pions data-MC 1.Study of background sources m+m-g : new generation based on phokhara3 Trackmass: comparison data-MC

  3. M(mm) in pp hypothesys This curve is added to the fit function 239 pb-1 MC sample 360 evts surviving 526 evts in the full sample (6.8 x 105 data sample)

  4. p+p-p0 higher statistics new generation  new function to add in the fit p+p- new two-body generator done  see possible tail on the high mass region

  5. Present estimated backgrounds: Events m+m-g p+p-p0

  6. M(r0) and G(r0) forced M(r0) forced M(r0) and G(r0) Free (baseline fit) 2. r0 line shape and r0-w interference r0 mass and width (773.3 and 144.1 MeV) “not consistent” with p+p-p0 analysis (775.9±0.7 and 147.3±1.6 MeV). Try to force

  7. Fit with M(w) and G(w) free:r0 parameters do not change: values found: M(w) = 782.2 ± 0.6 (PDG) 782.59 ± 0.11 G(w) = 8.9 ± 0.8 (PDG) 8.49 ± 0.08 Are we sensitive to M(w) and G(w) ? Or do they Affect M(r0) and G(r0) determination ? Good momentum scale calibration. No smearing required

  8. 3. Three different fits to the same spectrum: KL = Kaon-loop approach (N.N.Achasov et al) IM = “no structure” (G.Isidori, L.Maiani) BP = based on scattering amplitudes (M.E.Boglione, M.Pennington)

  9. The fitting function: Free parameters: (1) for the “background” M(r0) G(r0) ab arp (2) for the “signal” KL ( mf gfKK R ) IM ( mfGf gg c0 c1 fase ) BP ( a1 b1 a2 b2 s0 fase )

  10. KL fit c2 = 541/481 P(c2)= 3.0% IM fit c2 = 540/478 P(c2)= 2.6% BP fit c2 = 521/478 P(c2)= 8.4%

  11. KL fit c2 = 131/100 IM fit c2 = 139/100 BP fit c2 = 119/100

  12. Summary of fit results

  13. KL vs IM (1): red = signal green = direct blue = interference KL IM Gf(KL) ~ 70 MeV , Gf(IM) ~ 21 MeV

  14. KL vs IM (2): different “rise” of the signal: it is due to the different propagator KL Flatte’- like gfab are the parameters IM

  15. KL vs IM (3): couplings: KL: g2fKK/4p =3.4 GeV2 gfKK = 6.4 GeV g2fpp/4p =1.2 GeV2 gfpp = 3.9 GeV IM: Gf = 21 MeV  gfpp = 1.0 GeV(*) gffggfpp = 1.6  gffg = 1.6 GeV-1 (*) assuming f  p+p- the only contribution to G

  16. IM : Effect of the c0 and c1 “background”: solid: c0 =0 , c1 =0 dashed: c0 and c1 fitted

  17. Size of the “scalar” signal respect to ISR: peak at f0 mass (size ~ 30%) rise at low masses KL IM Any low mass analysis requires knowledge of the scalar contributions

  18. 4. Charge asymmetry: in hep-ph/0412239 first attempts to predict the M(pp) behaviour. Full = data Open = MC FSR+ISR

  19. Conclusions • Some more checks on possible backgrounds (p+p-p0 andp+p-) are needed • The fit is OK (improve is possible for BP) • The charge asymmetry is an interesting issue • A message for hadronic cross-section measurement: take care of scalars even in the low mass region. • Define a strategy for publications.

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