Study of Kinematic Variables in Multi-Lepton Final States in search for an Exotic Higgs Boson

Sammanfattning: The Large Hadron Collider in Geneva was constructed as a discovery machine. So far, the Higgs boson has been the only discovery at the Large Hadron Collider, but physicists keep on pushing the limit in order to discover new particles. With the two major runs at the Large Hadron Collider showing some alluring surpluses of activity in multi-lepton final states, beyond the Standard Model theories are being explored in order to try to explain these excesses. One of the most prominent beyond the Standard Model theories consistent with these excesses is the 2HDM(+S) model. This theory postulates a new heavy Higgs boson $H$, decaying into the Standard Model Higgs boson $h$ and a singlet scalar $S$. This thesis investigates the decay products of $S$, which are different flavour leptons of opposite sign $\ell^{\pm}\ell^{\mp}$, by studying kinematic variables in three well-defined regions at different mass points of $H$ and $S$ with a fixed Standard Model Higgs mass of $m_h = \SI{125}{GeV}$.