%e formulate relativistic and nonrelativistic two-particle dynamics in such a manner that the two-body binding energies are the same for both. %e then formulate and solve the relativistic Faddeev equations for a simple s-wave potential (Malfliet-Tjon V). The relativistic effects are small {about 3%}and reduce the three-body binding energy. The expectation value of the relativistic energy operator with the nonrelativistic wave function is a fairly good approximation, but approximate expressions involving expansions in powers of the momentum are shown to be quite unreliable.

The dynamical model developed in [Phys. Rev. C 54, 2660] has been applied to investigate the pion electroproduction reactions on the nucleon. It is found that the model can describe to a very large extent the recent data of p(e, e ′ π 0 ) reaction from Jefferson Laboratory and MIT-Bates. The extracted magnetic dipole(M1), electric dipole(E2), and Coulomb(C2) strengths of the γN → ∆ transition are presented. It is found that the C2/M1 ratio drops significantly with Q 2 and reaches about -13% at Q 2 =4 (GeV/c) 2 , while the E2/M1 ratio remains close to the value ∼ −3% at the Q 2 = 0 photon point.The determined M1 transition form factor drops faster than the usual dipole form factor of the proton. We also find that the non-resonant interactions can dress the γN → ∆ vertex to enhance strongly its strength at low Q 2 , but much less at high Q 2 . Predictions are presented for future experimental tests.Possible developments of the model are discussed. PACS number(s): 13.75. Gx,21.45.+v,25.20.Lj

We study nucleon-to-delta electromagnetic transition form factors and relations between them within the framework of the holographic dual model of QCD proposed by Sakai and Sugimoto. In this setup, baryons appear as topological solitons of the five-dimensional holographic gauge theory that describes a tower of mesons and their interactions. We find a relativistic extension of the nucleon-delta-vector meson interaction vertices and use these to calculate transition form factors from holographic QCD. We observe that at low momentum transfer, magnetic dipole, electric and Coulomb quadrupole form factors and their ratios follow the patterns expected in the large Nc limit. Our results at this approximation are in reasonable agreement with experiment. *

The absorption of π + on 3 He in the ∆-region is evaluated with exact inclusion of the final state interaction among the three emerging protons. The absorption is described by a πN → ∆ vertex and a N ∆-N N transition t-matrix which are calculated from a phenomenological model for N N and πd reactions. In a calculation where the initial pion scattering effects are neglected, the predicted peaks of the pion absorption cross sections for 2 H and 3 He lie too high in energy in relation to the data. The effect of the final state three-nucleon interaction turns out to be too small for changing the magnitude and shifting the peak position of the total absorption cross section for 3 He. We demonstrate that the adjustment of the peak position for the deuteron cross section by small modifications of the ∆-parameters, automatically leads to the correct peak position in 3 He. 25.10.+x, 25.80.Ls

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