In this paper we present a complete and exact spectral analysis of the
(1+1)-dimensional model that Jackiw and Rebbi considered to show that the
half-integral fermion numbers are possible due to the presence of an isolated
self charge conjugate zero mode. The model possesses the charge and particle
conjugation symmetries. These symmetries mandate the reflection symmetry of the
spectrum about the line
E=0. We obtain the bound state energies and wave
functions of the fermion in this model using two different methods,
analytically and exactly, for every arbitrary choice of the parameters of the
kink, i.e. its value at spatial infinity (
θ0) and its scale of
variations (
μ). Then, we plot the bound state energies of the fermion as a
function of
θ0. This graph enables us to consider a process of building
up the kink from the trivial vacuum. We can then determine the origin and
evolution of the bound state energy levels during this process. We see that the
model has a dynamical mass generation process at the first quantized level and
the zero-energy fermionic mode responsible for the fractional fermion number,
is always present during the construction of the kink and its origin is very
peculiar, indeed. We also observe that, as expected, none of the energy levels
crosses each other. Moreover, we obtain analytically the continuum scattering
wave functions of the fermion and then calculate the phase shifts of these wave
functions. Using the information contained in the graphs of the phase shifts
and the bound states, we show that our phase shifts are consistent with the
weak and strong forms of the Levinson theorem. Finally, using the weak form of
the Levinson theorem, we confirm that the number of the zero-energy fermionic
modes is exactly one.