  Two-parton correlations in the pion, a non perturbative information encoded
in double parton distribution functions, are investigated in the Nambu and
Jona-Lasinio model. It is found that double parton distribution functions
expose novel dynamical information on the structure of the pion, not accessible
through one-body parton distributions, as it happens in several estimates for
the proton target and in a previous evaluation for the pion, in a light-cone
framework. Expressions and predictions are given for double parton
distributions corresponding to leading-twist Dirac operators in the quark
vertices, and to different regularization methods for the Nambu and
Jona-Lasinio model. These results are particularly relevant in view of
forthcoming lattice data.
