1 / 19

Test of FSR in the process at DA F NE

Test of FSR in the process at DA F NE. G.Pancheri, O. Shekhovtsova, G. Venanzoni. INFN/LNF. EURIDICE Midterm Collaboration Meeting 8-12 Feb. 2005 Frascati. F p (s). F p (s). FSR in sQED (sQED VMD ). F p (s). But how good is this approximation?

clover
Download Presentation

Test of FSR in the process at DA F NE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Test of FSR in the process at DAFNE G.Pancheri, O. Shekhovtsova, G. Venanzoni INFN/LNF EURIDICE Midterm Collaboration Meeting 8-12 Feb. 2005 Frascati

  2. Fp(s) Fp(s) FSR in sQED (sQEDVMD) Fp(s) But how good is this approximation? sQED VMD is reasonable for the pp final state. But what about ppg final state ? Can we use for FSR the same value of Fp(s) as for pp ? An additional contribution is model-dependent, and probably very small. But must be estimated.

  3. Global structure of FSR tensor for P2 = s • charge conjugation symmetry • photon crossing symmetry and • gauge invariance e*

  4. gauge invariant tensors: scalar (model dependent) functions Limit of soft photon (what we call sQED), in fact VMD*sQED At threshold (very hard photon) this approximation could not work fi=fisQED+Dfi

  5. (S. Dubinsky et al,hep-ph/041113) FSR in ChPT with  and a1 mesons G.Ecker et al., Nucl. Phys B321, 311 (1989) The contribution with r+,- (instead of a1), turns out to be negligible

  6. 4 model parameters: f , FV, GV, FA We calculate fi in ChPT(S. Dubinsky et al,hep-ph/0411113) • ppg contribution to am (analytical results) • Contribution to dsppg/dQ2pp spectrum and charge asymmetry (Monte Carlo)

  7. ppg contribution to am 10-9 10-8 10-13 10-12 Differential contribution to , where  is hard ( >Ecut) am (pp) ~ 500(5) 10-10 am (ppgsQED) 5 10-10 Dam (ppgCHPT) 0.1 10-10 below current experimental precision

  8. Contribution of FSRCHPT to dsppg/dQ2pp spectrum and charge asymmetry The following matrix element has been introduced in a MC, for e+e- p+p-g (based on EVA structure): S. Binner et al. Phys. Lett. B 459 (1999) • We neglect the contributions from g*rp p+p-g (found • to be negligible in hep-ph/0411113) • We included the direct decay f p+ p- g, important at s=mf2. This contribution (which is model dependent) affects also the low Q2pp region. Charge asymmetry can help to distinguish between various models (see the talk of H. Czyz) • We consider KLOE large angle analysis: 50o< qg< 130o, 50o<qp< 130o (S. Mueller talk)

  9. We included fp+ p- g decay in our calculation, by looking to the channel f p0p0g (similar to H. Czyz et al. hep-ph/0412239) We use the Achasov 4quark parametrization with the parameters of the model taken from the fit of the KLOE data f p0p0g. (fp+ p- g is related to fp0 p0 g by isospin symmetry) dBR/dm x 108 (MeV-1) CAVEAT: For the moment we consider only the contribution of f0 (no s meson). This could be too crude for low Q2 ! mpp(MeV)

  10. (Analytical) Comparisons (at s=mf2): 0o<qp< 180o 0o<qg< 180o = FSRsQED+Df dsppg /dQ2 (nb/GeV2) =fp+ p- g resonant cont. = FSRsQED Since MFSR*Mf |Mf|2 at low Q2 Df can be relevant only for destructive interference (we will consider only this case in the following) = Df Q2(GeV2) What happens for s<mf2 ?

  11. The comparison at s=1 GeV2 (off fpeak): 0o<qp< 180o 0o<qg< 180o = FSRsQED+Df dsppg/dQ2 (nb/GeV2) =100·fp+ p- g resonant cont. Multiplied by a factor 100 = FSRsQED = Df 1/|Df(s)|2 s 1.04 GeV 1.04 GeV 1 GeV Q2(GeV2) In this case the interference MFSR*Mf is expected to be >>|Mf|2 • We could not neglect the interference contribution (i.e. f contr.), but the work off the resonance region is attractive (3 p backgroundis much less)

  12. s=mf2 50o<qp< 130o 50o<qg< 130o Numerical results:differential cross section… dsTOT/dssQED ds/dQ2 (nb/GeV2) dssQED+f/dssQED = ISR+FSRsQED = ISR+FSRsQED + f dsTOT/dssQED+f = ISR+FSRCHPT + f Q2(GeV2) Q2(GeV2) Effect al low Q2…however the contribution of f is not much accurate (no interference with s has been taken into account)

  13. A closer look at the threshold region: dsTOT/dssQED ds/dQ2 (nb/GeV2) dssQED+f/dssQED = ISR+FSRsQED dsTOT/dssQED+f = ISR+FSRsQED + f = ISR+FSRCHPT + f 0.35 0.35 Q2(GeV2) Q2(GeV2) Up to 30% of contribution beyond sQED at the threshold. Results are sensitive to FSR model

  14. And asymmetry… = ISR+FSRsQED = ISR+FSRCHPT + f = ISR+FSRsQED + f -25% Q2(GeV2)

  15. Conclusions and outlook • First MC results on a generalization of FSR using ChPT with  and a1 mesons have been presented. • A sizeable effect can be seen on the cross section (at low Q2 only). • The situation on the asymmetry ismore complicate. • the result strongly depends on the parametrization of the f direct decay.

  16. For the near future: • Improve the simulation: • better parametrization of f (including also the s meson) • study of the dependence of results on the various parameters of the models in MC • New theoretical tasks • improve the knowledge on the phi decay (in particular at low Q2): to consider the phi decay in ChPT • try to take into account  and  ' mesons contribution in ChPT • Try to disentangle the various contributions: • asymmetry, and other kinematical variables (angular distributions) • Model independent analysis of fi  different kinematics region? • Work off resonance

  17. Disclaimer: all our numerical results are preliminary!!!The theoretical results is only the first step out sQED!!!

  18. BACKUP SLIDES

  19. Asymmetry ISR+FSRsQED + f ISR+FSRsQED Q2(GeV) Q2(GeV)

More Related