  We present a fully backreacted D3-D7 supergravity solution dual to the
Klebanov-Strassler cascading gauge theory coupled to a large number of massive
dynamical flavors in the Veneziano limit. The mass of the flavors can be larger
or smaller than the dynamically generated scale. The solution is always regular
at the origin of the radial coordinate and as such it can be suitably employed
to explore the rich IR physics of the dual gauge theory. In this paper we focus
on the static quark-antiquark potential, the screening of chromoelectric
charges induced by the dynamical flavors, the flux tube breaking and the mass
spectrum of the first mesonic excitations. Moreover, we discuss the occurrence
of quantum phase transitions in the connected part of the static
quark-antiquark potential. Depending on the ratio of certain parameters, like
the flavor mass, with respect to some critical values, we find a discontinuous
(first order) or smooth transition from a Coulomb-like to a linear phase. We
evaluate the related critical exponents finding that they take classical
mean-field values and argue that this is a universal feature of analogous first
order transitions occurring in the static potential for planar gauge theories
having a dual supergravity description.
