Exploring Baryon Asymmetry and Naturalness with the Current Experimental Data and Observations

This thesis explores some extensions of the Standard Model in search of new physics. The research presented here concerns aspects of cosmology and collider physics. The research includes a combination of model building, constraints imposed by the current experimental data, and prospects of future experimental bounds. There is an aggregate of three main research projects composing this thesis. Firstly, the possibility of multiple hidden sectors to accommodate a successful framework to explain the abundance of matter over anti-matter and study prospects of a viable dark matter candidate. The evolution of cosmological history and the baryon asymmetry is studied thoroughly. The baryon asymmetry and the dark matter relic abundance are checked in light of the current cosmological data and a potential parameter space is computed. The analysis conducted reveals that a viable mechanism for the origin of matter and a feasible model for dark matter can be constructed considering the multiple hidden sectors framework. Secondly, we study the phenomenology of an extension of the Standard Model with fermionic top partners. The introduction of such new particles gives rise to rich collider phenomenology which is examined given the copious amount of data collected at the Large Hadron Collider. The discovery potential and the constrained parameter space for the proposed model are derived and discussed in great detail. The various available collider searches for top partners suggest that the limits obtained on the fully hadronic decay channels of the proposed model are less stringent compared to the traditional decay modes and the effects of future dedicated searches are outlined. Finally, a dedicated study analyzing some aspects of supersymmetric quantum chromodynamics (SQCD) like gauge theories is conducted. In particular, exploring the behaviour of a sub-category of SQCD theories which confines without chiral symmetry breaking for three quark flavours. The computations of the SQCD with the anomaly-mediated supersymmetry breaking effects lead to the conclusion that for the three flavour scenario, the scalar potential does not have a minimum away from the origin.