  A first search for same-sign WW production via double-parton scattering is
performed based on proton-proton collision data at a center-of-mass energy of 8
TeV using dimuon and electron-muon final states. The search is based on the
analysis of data corresponding to an integrated luminosity of 19.7 fb$^{-1}$.
No significant excess of events is observed above the expected single-parton
scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the
inclusive cross section for same-sign WW production via the double-parton
scattering process. This upper limit is used to place a 95% confidence level
lower limit of 12.2 mb on the effective double-parton cross section parameter,
closely related to the transverse distribution of partons in the proton. This
limit on the effective cross section is consistent with previous measurements
as well as with Monte Carlo event generator predictions.

High Energy Physics - Experiment