Neutral Scalar Higgs searches using Vector Boson Fusion at ATLAS

The Higgs boson is the last undiscovered particle predicted by the Standard Model. Its discovery is key to our understanding of the electroweak symmetry breaking process and the origin of mass. The primary purpose of the ATLAS detector at the Large Hadron Collider is the discovery of this particle. This thesis evaluates the discovery potential of the ATLAS experiment for a Heavy Neutral Scalar Higgs boson, $\text{M}_{H} \ge 170 ~\text{\GEVCC}$, produced through vector boson fusion and decaying through the four physics channels : H$\rightarrow$ZZ$\rightarrow l^{+}l^{-}$+jj and H$\rightarrow$WW$\rightarrow l\nu_{l}$+jj where l~=~e,$\mu$. \\ The analysis has been performed using the PYTHIA 6.227 Monte-Carlo generator and the ATLAS fast simulation package ATLFAST. This fast simulation package has been modified such that the results are in agreement with the full simulation program DICE/ATRECON. The ATLFAST package has also been modified to include electronic noise and low and high luminosity pileup. \\ This thesis demonstrates that even when the large systematic uncertainties are addressed a neutral scalar Higgs boson can be discovered after 3 years of running at low luminosity (collecting 30 \invfb at L=1$\times$\lowlumi) if its mass were between 170 \GEVCC $ <M_{H} < $ 190 \GEVCC or above 280 \GEVCC. The Higgs boson can also be discovered after running for 1 year at high luminosity (collecting 100 \invfb at L=1$\times$\highlumi) if its mass were between 170 \GEVCC $ <M_{H} < $ 180 \GEVCC or above 290 \GEVCC.