  The relative distribution of abundances of refractory, intermediate, and
volatile elements in stars with planets can be an important tool for
investigating the internal migration of a giant planet. This migration can lead
to the accretion of planetesimals and the selective enrichment of the star with
these elements. We report on a spectroscopic determination of the atmospheric
parameters and chemical abundances of the parent stars in transiting planets
CoRoT-2b and CoRoT-4b. Adding data for CoRoT-3 and CoRoT-5 from the literature,
we find a flat distribution of the relative abundances as a function of their
condensation temperatures. For CoRoT-2, the relatively high lithium abundance
and intensity of its Li I resonance line permit us to propose an age of 120
Myr, making this stars one of the youngest stars with planets to date. We
introduce a new methodology to investigate a relation between the abundances of
these stars and the internal migration of their planets. By simulating the
internal migration of a planet in a disk formed only by planetesimals, we are
able to separate the stellar fractions of refractory (R), intermediate (I), and
volatile (V) rich planetesimals accreting onto the central star. Intermediate
and volatile element fractions enriching the star are similar and much larger
than those of pure refractory ones. We also show that these results are highly
dependent on the model adopted for the disk distribution regions in terms of R,
I, and V elements and other parameters considered. We note however, that this
self-enrichment mechanism is only efficient during the first 20-30 Myr or later
in the lifetime of the disk when the surface convection layers of the central
star for the first time attain its minimum size configuration.
