  The underlying event measurement may be crucial for the new physics searches
at high energies at LHC. This study presents the influence of double parton
scattering on the same-sign di-muon production, where only the positive charge
is taken into account for now. The signal production cross section is found to
be 0.94 fb within the kinematic range of the ATLAS detector. This creates
around 25 per cent of the total cross section for the searched final state.
