Minijets and the Two-Body Parton Correlation

A large number of double parton scatterings have been recently measured by CDF. The double parton scattering process measures $\sigma_{eff}$, a non perturbative quantity related to the hadronic transverse size and with the dimensions of a cross section. The actual value measured by CDF is considerably smaller as compared with the naive expectation, namely the value of the inelastic non diffractive cross section. The small value of $\sigma_{eff}$ may be an effect of the hadron structure in transverse plane. We discuss the problem by taking into account, at all orders, the two-body parton correlations in the many-body parton distributions.Comment: 19 pages, plane tex, no figure

Temperature and Density Effects on the Nucleon Mass Splitting

The finite temperature and finite density dependence of the neutron-proton mass difference is analysed in a purely hadronic framework where the $\rho-\omega$ mixing is crucial for this isospin symmetry breakdown. The problem is handled within Thermo Field Dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei.Comment: 17 pages, revtex fil