  Double parton distribution functions (dPDF) represent a tool to explore the
3D proton structure. They can be measured in high energy proton-proton and
proton nucleus collisions and encode information on how partons inside a proton
are correlated among each other. dPFDs are studied here in the valence quark
region, by means of a constituent quark model, where two particle correlations
are present without any additional prescription. This framework allows to
understand the dynamical origin of the correlations and to clarify which, among
the features of the results, are model independent. Use will be made of a
relativistic light-front scheme, able to overcome some drawbacks of the
previous calculation. Transverse momentum correlations, due to the exact
treatment of the boosts, are predicted and analyzed. The role of spin
correlations is also shown. Due to the covariance of the approach, some
symmetries of the dPDFs are seen unambigously. For the valence sector, the
study of the QCD evolution of the model results, which can be performed safely
thanks to the property of good support, has been also completed.
