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On description of resonance region in the FKR model

On description of resonance region in the FKR model. Krzysztof M. Graczyk , Jan T. Sobczyk Institute of Theoretical Physic s University of Wrocław Poland. Motivations. Modification of the FKR model  Rein-Sehgal model  MC generators

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On description of resonance region in the FKR model

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  1. On description of resonance region in the FKR model Krzysztof M. Graczyk, Jan T. Sobczyk Institute of Theoretical Physics University of Wrocław Poland

  2. Motivations • Modification of the FKR model  Rein-Sehgal model  MC generators • Model which will better fit to experimental data in D(1232) region • Another idea of introducing form factors (effective) • We still keep only two form factors (vector and axial) • Lepton mass in Charged Current nN scattering • 7 new resonances How modification I affects cross section for Single Pion Production (SPP) in Neutral Current (NC)nN scattering?

  3. Two Form Factors FKR and RS models • Feynman, Kislinger, and Ravndal 71 • Electroproduction: Ravndal 71 • Neutrinoproduction: Ravndal 72, 73, Rein and Sehgal 81, Rein 87 • Baryon wave function Sym[SU(3)xSU(2)xO(3)] representation Elastic Limit of the description FKR MODEL ELASTIC SCATTERING Form Factors of the FKR/RS model are expressed by elastic nucleon form factors!!! This is not the only way of computing form factors

  4. F2 underestimated in the FKR model Electroproduction Neutrinoproduction F. Ravndal, Phys. Rev. D 4, 1466 (1971) F. Ravndal, Nuovo Cimento, 18A 385 (1973) Let’s introduce another Vector FF Form Factor model for D(1232) excitation O. Lalakulich, E. A. Paschos and G. Piranishvili, Phys. Rev. D 74 (2006) 014009 M. Osipenko et al., The proton structure function F2 in the resonance regio, arXiv:hep-ex/0301033

  5. FKR Form Factor Evaluation Form Factor model for D(1232) excitation New effective vector form factor

  6. Significant correction for small Q2

  7. New effective axial form factor O. Lalakulich, E. A. Paschos, Phys.Rev.D71:074003,2005 nN interaction Axial part

  8. SPP in NC nN scattering D. Rein, L. Sehgal Annals Phys.133:79,1981. We have different proportion of the vector and axial contribution!!! almost 2 times more

  9. SPP in NC nN scattering W< 2 GeV

  10. SPP in CC nN scattering W< 2 GeV

  11. We introduced lepton mass into the model. It was done in a different way than V. Naumov et al.. Nucl.Phys.Proc.Suppl.139:158-161,2005 Effect of the lepton mass Lepton mass The matrix elements of the Jt and Jz components of the hadronic current were computed separately

  12. Does not contribute 25 18 Some difficulties !!! to get a space part of the resonances wave functions for third and fourth level of the oscillator, Hey et al. Phys. Rept. 96 (1983) 71. F2(ep) structure functions Only resonance contribution

  13. Summary • We proposed three improvements: • New form factors – the most significant, in particular for the 1p0 production in NC reactions • Lepton mass – relevant for small Q2 • Heavier resonances – not significant

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