Flavor content of nucleon form factors
Abstract
Description
The flavor content of nucleon form factors is analyzed using two different theoretical approaches. The first is based on a phenomenological two-component model in which the external photon couples to both an intrinsic three-quark structure and a meson cloud via vector-meson dominance. The flavor content of the nucleon form factors is extracted without introducing any additional parameter. A comparison with recent data from parity-violating electron scattering experiments shows a good overall agreement for the strange form factors.
A more microscopic approach is that of an unquenched quark model proposed by Geiger and Isgur which is based on valence quark plus glue dominance to which quark-antiquark pairs are added in perturbation. In the original version the importance of $s \bar{s}$ loops in the proton was studied. Here we present the formalism for a new generation of unquenched quark models which, among other extensions, includes the contributions of $u \bar{u}$ and $d \bar{d}$ loops. Finally, we discuss some preliminary results in the closure limit.
10 pages, 5 figures, 1 table, invited talk at XXX Symposium on Nuclear Physics, Cocoyoc, Morelos, Mexico, January 3-6, 2007, to be published by Revista Mexicana de Fisica
10 pages, 5 figures, 1 table, invited talk at XXX Symposium on Nuclear Physics, Cocoyoc, Morelos, Mexico, January 3-6, 2007, to be published by Revista Mexicana de Fisica