0000000001186653
AUTHOR
José Carlos Nácher Díez
Two pion electroproduction
We have extended a model for the γN→ππN reaction to virtual photons and selected the diagrams which have a Δ in the final state. The agreement found with the γvp→Δ0π+ and γvp→Δ++π− reactions is good. The sensitivity of the results to NΔ transition form factors is also studied. The present reaction, selecting a particular final state, is an extra test for models of the γvN→ππN amplitude.
A model for pi Delta electroproduction on the proton
We have extended a model for the γN→ππN reaction to virtual photons and selected the diagrams which have a Δ in the final state. With this model we have evaluated cross sections for the virtual photon cross section as a function of Q2 for different energies. The agreement found with the γvp→Δ0π+ and γvp→Δ++π− reactions is good. The sensitivity of the results to NΔ transition form factors is also studied. The present reaction, selecting a particular final state, is an extra test for models of the γvN→ππN amplitude. The experimental measurement of the different isospin channels for this reaction are encouraged as a means to unravel the dynamics of the two pions photoproduction processes.
Chiral unitary approach to the pi N*N*, eta N*N* couplings for the N* (1535) resonance
Using a chiral unitary model in which the negative parity nucleon resonance N∗≡N∗(1535) is generated dynamically by means of the Bethe Salpeter equation with coupled meson baryon channels in the S=0 sector, we have obtained the π0N∗N∗ and ηN∗N∗ couplings. The π0N∗N∗ coupling has smaller strength and the same sign as the π0NN coupling. This rules out the mirror assignment of chiral symmetry where the ground state nucleon N and the negative parity resonance N∗ are envisaged as chiral partners in the baryon sector.