The CP-violation necessary for the generation of the baryon asymmetry of the
Universe YB​ in the "flavoured" leptogenesis scenario can arise from the "low
energy" PMNS neutrino mixing matrix U and/or from the "high energy" part of
neutrino Yukawa couplings, which can mediate CP-violating phenomena only at
some high energy scale. The possible interplay between these two types of
CP-violation is analysed. The type I see-saw model with three heavy
right-handed Majorana neutrinos having hierarchical spectrum is considered. We
show that in the case of inverted hierarchical light neutrino mass spectrum,
there exist regions in the corresponding leptogenesis parameter space where the
relevant "high energy" phases have large CP-violating values, but the purely
"high energy" contribution in YB​ plays a subdominant role in the production
of baryon asymmetry compatible with the observations. In some of these regions
the purely "high energy" contribution in YB​ is so strongly suppressed that
one can have successful leptogenesis only if the requisite CP-violation is
provided by the Majorana phase(s) in the neutrino mixing matrix.Comment: Version accepted for publication in Phys. Lett. B; Addendum, in which
the numerical analysis is extended to the case of complex R_{13} element, and
one figure adde