Electromagnetic Form Factors of Nucleons in a Relativistic Three-Quark Model

Abstract

We report the calculation of electromagnetic form factors of nucleons within a relativistic three-quark model with Gaussian shape for the nucleon-quark vertex. The allowed region for two adjustable parameters, the range parameter N in the Gaussian and the constituent quark mass m q , is obtained from tting the data for magnetic moments and electromagnetic radii of nucleons. The shapes of electric and magnetic nucleon form factors calculated in this approach with the central parameters m q =420 MeV and N =1.25 GeV are close to the data for momentum transfers 0 Q 2 1 GeV 2 .

Axial form factor of the nucleon in the perturbative chiral quark model

“…The model clearly underestimates the finite Q 2 -behavior, but it should be noted that a similar effect occurs in the discussion of the electromagnetic form factors of the nucleon [9]. The stiffness of the form factors can be traced to the Gaussian ansatz of the single quark wave functions and can also be improved when in addition resorting to a fully covariant description of the valence quark content of the nucleon [30]. Hence the applicability of the PCQM is mostly for static quantities and low Q 2 observables of baryons.…”

Semileptonic decays of double heavy baryons

“…In the present paper we, however, choose a more phenomenological approach where the vertex functions are modelled by Gaussian forms and the quark propagators are given by local representations. We have demonstrated in our papers [6,11] that the relativistic constituent model is consistent with the heavy quark symmetry in the limit of infinite quark masses. We mention that the authors of [12] have developed a relativistic quark model approach for meson transitions which shows some similarities to our approach.…”

“…As concerns the vertex functions, we found a good description of various physical quantities [5,6,11,13] adopting a Gaussian form. Here we apply the same procedure using φ H (k 2 E ) = exp{−k 2 E /Λ 2 H } in the Euclidean region.…”

“…The magnitude of Λ H characterizes the size of the vertex function and is an adjustable parameter in our model. The Λ H parameters in the meson sector were determined [6] by a leastsquares fit to experimental data and lattice determinations. The nucleon Λ N parameter was determined from the best description of the electromagnetic properties of the nucleon [6].…”

Electromagnetic properties of nucleons and hyperons in a Lorentz covariant quark model

“…Next, we use this Lagrangian to perform a dressing of the operators of constituent quarks by a cloud of light pseudoscalar mesons and by other heavy states. Then we discuss the calculation of matrix elements of dressed quark operators between baryons states using a specific constituent quark model [6]- [8]. In Sec.…”