Two-component model for lepton pair production in hadron collisions

We present a model for lepton pair production in hadron collisions into which two different production mechanisms are incorporated simultaneously. They are the mechanisms due to the hard interactions of the energetic constituents (partons) in a hadron and due to the soft interactions. We can unify the two mechanisms by solving the Boltzmann equation of parton probability distributions which describes the time-evolution process of hadron collisions. Our model can reproduce well the experimental data on the nonresonant continuum spectrum from small (above 1 ${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c}}^2$) to large pair mass.