  In this work, following recent studies which show that it is possible to
localize gravity as well as scalar and gauge vector fields in a tachyonic de
Sitter thick braneworld, we investigate the localization of fermion fields in
this model. In order to achieve this aim we consider the Yukawa interaction
term between the fermions and the tachyonic condensate scalar field
MF(T)barPsiPsi in the action and analyze four different cases corresponding to
distinct tachyonic functions F(T(w)). The only condition that this function
must satisfy in order to yield 4D chiral fermions upon dimensional reduction is
to be odd in the extra dimension w. These functions lead to a different
structure of the respective fermionic mass spectrum. In particular,
localization of the massless left-chiral fermion zero mode is possible for
three of these cases. We further analyze the phenomenology of the Yukawa
interaction among fermion fields and gauge bosons localized on the brane and
obtain the crucial and necessary information to compute the corrections to
Coulomb's law coming from massive KK vector modes in the non-relativistic
limit. These corrections are exponentially suppressed due to the presence of
the mass gap in the mass spectrum of the bulk gauge vector field. From our
results we conclude that corrections to Coulomb's law in the thin brane limit
have the same form (up to a numerical factor) as far as the left-chiral
massless fermion field is localized on the brane. Finally we compute the
corrections to the Coulomb's law for a more general case, on a thick brane
scenario, for which we can do estimates consistent with brane phenomenology,
i.e. we found that the predicted corrections to the Coulomb law in our model,
which are well bounded by the observed experimental photon mass, is far beyond
its upper bound, positively testing the viability of our tachyonic braneworld.
