  We study the electroweak properties of pseudo-scalar mesons in the light and
heavy-light sectors. In particular, we address the electromagnetic form factors
and decay constants of the pion, kaon and D mesons. The structure of composite
systems are given by the Bethe-Salpeter (BS) amplitude of a meson formed by a
confined pair of constituent quark and antiquark, which in our work is written
in terms of Pauli-Villars regulators. The analytical structure contains single
poles in the complex momentum space. The BS amplitude takes into account poles
due to the regulator parameters, while the quark-antiquark cut is avoided,
implying in confined quarks with the property that the sum of the constituents
masses can be larger than the mass of the meson. The one-loop expressions of
the electroweak transition amplitudes are conveniently written in terms of
light-front momentum. Technically, we introduce a Wick-rotation of he minus
component of the momentum (k-minus) in the one-loop amplitudes allowing to
avoid the cuts in the complex plane of this momentum variable without crossing
them. This is particularly useful as we can study the electroweak properties
with several models of the BS amplitude with different powers of Pauli-Villars
regulators. The possibility to change the power of the BS amplitude is
interesting in order to test the asymptotic behavior of the electromagnetic
form factors searching for a suitable form that incorporates the expected QCD
decaying power-law form. The results are compared with others models in the
literature and with the experimental data.
