Abstract
Double Parton Scattering (DPS) is the interaction of two hard processes within proton-proton collisions. This dissertation presents the observation of DPS with same-sign \ssww production with the 140 $\mathrm{fb}^{-1}$ dataset at a center-of-mass energy of $\sqrt{s}=13$ TeV using the ATLAS experiment at the LHC. Neural networks are trained to separate DPS \ssww events from other backgrounds to enhance sensitivity. A binned maximum likelihood function of the neural network outputs is utilized to extract the cross section. The DPS \ssww process is observed at ATLAS with a $8.7\sigma$ significance. The measured fiducial DPS \ssww cross section is $4.68 \pm 0.67~\mathrm{fb}$ and a total cross section with the $W^\pm$ boson decaying leptonically is $\sigma = 108 \pm 16 ~\mathrm{fb}$ at ATLAS. The DPS effective cross section is measured to be $\sigma_{\mathrm{eff}}=9.1 \pm 1.3 ~\mathrm{mb}$.