Differential Cross Section Measurement of the $pp\rightarrow WH\rightarrow WWW$ Process With the ATLAS Experiment

In this thesis, a Simplified Template Cross Section (STXS) analysis for the $ pp\rightarrow WH\rightarrow WWW\rightarrow l\nu l\nu l\nu$ process is presented, using final states with no lepton pairs of the same flavor and opposite charge. The analysis uses proton-proton collisions at a center of mass energy of $13~TeV$ with an integrated luminosity of $139~fb^{-1}$, which were measured by the ATLAS detector at the Large Hadron Collider. Neural networks are used to reconstruct the transverse momentum of the associated $W$ boson and to separate signal and background. The expected signal strengths of the STXS bins were measured to be $\mu(0~GeV\leq p_T^W<75~GeV)=1\pm 1.24$, $\mu(75~GeV\leq p_T^W<150~GeV)=1\pm 1.52$, $\mu(150~GeV\leq p_T^W<250~GeV)=1\pm 2.20$ and $\mu(p_T^W\geq 150~GeV)=1\pm 2.22$.