Proton and neutron form factors with quark orbital excitations

Abstract

Nucleon form factors play an especially important role in studying the dynamics of nucleons and explicit structure of the wave functions at arbitrary nucleon velocity. The purpose of the paper is to explain theoretically all four nucleon form factors measured experimentally in the cross section measurements (by the Rosenbluth method), yielding almost equal normalized form factors G p E , G p M , G n M ), as well as in the polarization transfer experiments, where a strongly decreasing proton electric form factor has been discovered. It is shown, using relativistic hyperspherical formalism, that the nucleon wave functions in the lowest approximation provide almost equal normalized form factors as seen in the Rosenbluth cross sections, but in the higher components they contain a large admixture of the quark orbital momenta, which strongly decreases G p E and this effect is possibly detected in the polarization transfer method (not seen in the classical cross section experiments). Moreover, the same admixture of the higher components explains the small positive form factorGeV 2 , using the standard and the Lorentz contracted wave functions and shown to be in reasonable agreement with experimental data.

Hadron wave functions in high-energy scattering, form factors and strong decays: the effects of the Lorentz contracted form

“…Assuming an exact Lorentz contracted form for the wave functions participating in the same matrix element with different velocities it was found that meson form factors well reproduce experimental data [32],and the same is true for the baryon form factors at least for moderate Q values [33]. Finally the same LC effect helps to understand the strong ρ decays [34]. It is a purpose of this paper to understand better the effects of LC in different physical systems in the whole range of Q values and for this purpose we consider the case of the hadron-hadron scattering with the one hadron exchange.…”

“…In this respect it is interesting what happens with the momentum dependent wave function when it experiences a Lorentz boost. As it was discussed in [2,3,4,5,7,8,9,11,12,27,28,29,30,31,32,33,34] and below in this paper,the x-space and p-space (pseudo)scalar q q wave functions moving with the velocity v have the form…”

Understanding two slopes in the pp (p\bar p) differential cross sections

“…does not contain any internal angular momenta of the quarks, which can influence the Q dependence of the form factors. It is clear that the ground states of the 3q system have in the dominant component the wave function ψ(ρ), which is called the hypercentral approximation in the framework of the hyperspherical approach, developed in [18], originally in nuclear physics, and was used in the relastivistic formalism with the relativistic Hamiltonian in [19] to calculate the baryon masses [19], the magnetic moments [20], and the form factors [21] in good agreement with experimental data.…”

“…We also define the corresponding momentum variables: q = ∂ i∂ξ , k = ∂ i∂η , and also the proton wave functions in the momentum space in the simple Gaussian form, which is close to the wave function, calculated in [19,20,21] for protons and neutrons:…”