[SEMINARI]: Dr. Pelaez: The Inverse Amplitude Method and Heavy Barion Chiral Perturbation Theory applied to pion Nucleon scattering

[Arcadi Santamaria]

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                              S E M I N A R I

        [Image]        Departament de Física Teòrica         [Image]
                  Universitat de València - IFIC (UV-CSIC)
                      46100 Burjassot (València) Spain

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        The Inverse Amplitude Method and Heavy Barion Chiral Perturbation
                    Theory applied to pion Nucleon scattering

                            Dr. Jose Ramon Pelaez

                          (Univ. Compl. de Madrid)

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         Sala de Juntes de l'edifici de l'IFIC a Paterna, primer pis
                Thursday 24 of February of 2000 at 11:30 AM
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                                    Resum

      By means of the Inverse Amplitude Method we unitarize the elastic
    pion-nucleon scattering amplitudes obtained from Heavy Baryon Chiral
Perturbation Theory to $\Od(q^3)$. Within this approach we can enlarge their
applicability range and generate the $\Delta(1232)$ resonance. We can find a
  reasonable description of the pion nucleon phase shifts with $\Od (q^2)$
 parameters in agreement with the resonance saturation hypothesis. However,
   the uncertainties in the analysis of the low energy data as well as the
large number of chiral parameters, which can have strong correlations, allow
 us to obtain very good fits with rather different sets of chiral constants.
    We also comment on possible reorderings of the expansion which, once
         unitarized, provide a remarkable description of the data.

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