Modification of the dihadron fragmentation function in nuclear matter

The medium modification of dihadron fragmentation functions in the deeply inelastic scattering (DIS) off a large nucleus is studied within the framework of the higher-twist expansion in the collinear factorization formalism. It is demonstrated that the modification due to multiple parton scattering in the nuclear medium is similar to that of the single hadron fragmentation function. However, the conditional distribution of the associated hadron given by the ratio of dihadron to single hadron fragmentation function shows only slight modification. The final results depend modestly on the nuclear density distribution. Comparisons with the experimental results on two hadron correlations as obtained by the HERMES collaboration at DESY are presented.