The Higgs Width in Higgs production in association with a W+ boson

Sammanfattning: The width of the Higgs boson is a quantity that cannot be measured directly from the on-shell Higgs peak; it would have to be measured indirectly. In 2013, Caola and Melnikov developed a method to determine the Higgs width by using off-shell and on-shell cross-sections and applying the narrow-width approximation. In this thesis, we will use the indirect method of finding the Higgs width for the production of the Higgs boson in association with a W+ boson. The specific decay mode of the scalar boson will be its decay to two Z bosons. In theory, this specific decay mode of the scalar boson must result in an off-shell and on-shell region. We simulated proton-proton collisions that produce the Higgs and W+ boson using the MadGraph5_MC@NLO software and, using the generated data, we were able to plot a histogram for when the Higgs width equals the Standard Model Higgs boson width calculated at LO accuracy. The same was done when the width is two times the Standard Model Higgs boson width and when it is five times the Standard Model Higgs boson width. From the analysis of the histograms and finding the total cross-section of the on-shell and off-shell region in each of the histograms, we found that the results agree with the relationship between the on-shell cross-section and the Higgs width when the narrow-width approximation is applied. The same can be said for the off-shell cross-section.