Searches for coloured supersymmetry with ATLAS at √s = 8 TeV, 13 TeV, and 14 TeV

The Standard Model of particle physics is describing the interactions of the smallest constituents in the Universe: the elementary particles which are divided into matter particles, leptons, and force carrying particles, bosons. The fundament of the Standard Model is symmetries which dictate the particle content and their interactions. By introducing a new type of symmetry, supersymmetry, between leptons and bosons predicting a bosonic partner of each Standard Model fermion and vice versa, some of the shortcomings of the Standard Model can be fixed. The supersymmetric partners of the Standard Model particles have not yet been observed placing their masses at a higher energy scale. In the high energy proton collisions at the Large Hadron Collider (LHC) at CERN it is possible to test the Standard Model at unprecedented energy scales and look for new, heavy particles, e.g supersymmetric particles. The ATLAS detector is designed to study the proton collisions in detail. This thesis presents searches for squarks and gluinos - the supersymmetric partners of the Standard Model quarks and gluons. The searches are performed at two collision energies, √s = 8 TeV and 13 TeV, in events with jets and missing transverse momentum with data collected by the ATLAS experiment. No excesses were observed and the results of the analyses are presented as limits on various supersymmetric models. The thesis also includes a study of the sensitivity of searches for squarks and gluinos with the dataset of an upgrade of the LHC to the HL-LHC at √s = 14 TeV.