Foliation, topology and nucleon charge profiles in hypersphere soliton model

Abstract

In the hypersphere soliton model (HSM), we study the geometrical inner structures and the ensuing charge distributions of the nucleons by exploiting the aspect of the HSM where the hypersphere soliton is described by an extended object possessing the parameter $\lambda$ $(0\le\lambda<\infty)$ which corresponds to the radial distance from the center of $S^{3}$ to the foliation leaves of the hypersphere soliton. To do this, we investigate the foliation and topology related with geometry on a hypersphere described by $(\mu,\theta,\phi)$. Exploiting the so-called scanning algorithm we study geometrical relations between spherical shell foliation leave on a northern hemi-hypersphere $S^{3}_{+}$ and that on a flat equatorial solid sphere $E^{3}$ which contains the center of $S^{3}$. We then elucidate the physical meaning of $\mu$ in $S^{3}$ of radius $\lambda$ by showing that $\mu$ plays the role of an auxiliary angle to fix the radius $\lambda\sin\mu$ of the $S^{2}$ spherical shell sharing the center of $S^{3}(=S^{2}\times S^{1})$, at a given angle $\mu$. Next, using the charge density profiles of nucleons with $\mu$ dependence, we construct the nucleon fractional charges of spherically symmetric and nontrivial distributions. In the HSM we note that the proton and neutron charges do not leak out from the hypersphere soliton, and the positive and negative charges in the neutron are confined inside and outside its core, respectively. Explicitly we predict the fractional volumes and charges of the neutron. The proton and neutron are shown to be described by a topological structure of two Hopf-linked M\"obius strip type twist circles in $S^{3}$. We also note that the characteristic ratio of the hypersphere volume to the corresponding solid sphere one is given by a geometrical invariant related with hyper-compactness.