Physics – High Energy Physics – High Energy Physics - Phenomenology
Scientific paper
2002-08-06
J.Phys.G29:405-430,2003
Physics
High Energy Physics
High Energy Physics - Phenomenology
Latex, 29 pages, 6 eps figures
Scientific paper
10.1088/0954-3899/29/2/316
Unitary and analytic ten-resonance model of the nucleon electromagnetic (e.m.) structure with canonical normalizations and QCD (up to the logarithmic correction) asymptotics is constructed on the four-sheeted Riemann surface, which provides a superposition of vector-meson pole and continuum contributions in a very natural way. As a result it describes simultaneously all existing experimental space-like and time-like data on the proton e.m. form factors (ff's) and on the neutron e.m. ff's as well. A crucial factor in the latter achievement is the inclusion of a contribution of the fourth excited state of the $\rho(770)$ meson with the parameters $m_{\rho''''}=2455\pm53 MeV, \Gamma_{\rho''''}=728\pm2 MeV$ and $(f^{(1)}_{\rho''''NN}/f_{\rho''''})=0.0549\pm0.0005$, $(f^{(2)}_{\rho''''NN}/f_{\rho''''})=-0.0103\pm0.0001$. The pronounced effect of the two-pion continuum on the isovector spectral functions demonstrating a strong enhancement of the left wing of the $\rho(770)$-resonance close to two-pion threshold, which was revealed by H\"ohler and Pietarinen by means of the nucleon ff unitarity condition more than a quarter of the century ago, is predicted by the model automatically. The model gives large values of the $f^{(1,2)}_{\phi NN}$ coupling constants, thus indicating the violation of the OZI rule. Since in the framework of the considered model isoscalar ff's above their lowest branch point $t^s_0=9m^2_{\pi}$ are complex functions, the isoscalar spectral function behaviours are predicted as well.
Dubnicka Stanislav
Dubnickova Anna Zuzana
Weisenpacher Peter
No associations
LandOfFree
Nucleon electromagnetic structure revisited does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nucleon electromagnetic structure revisited, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nucleon electromagnetic structure revisited will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-427741