Search for New Physics in Mono-jet Final States in pp Collisions

Giuliano Gustavino received his physics bachelor degree in 2011 from the University of L'Aquila, where he started to cultivate his interest in particle and astro-particle physics. In 2013 he obtained the master degree at the Sapienza University of Rome with a thesis on the study of the Higgs boson spin in the four leptons decay channel in the ATLAS experiment. In the same institution he worked for his PhD participating as main analyzer in the mono-jet analysis and focusing his work on the Dark Matter interpretation. He is currently employed as Postdoctoral Research Associate at the University of Oklahoma working on the ATLAS experiment.

This thesis provides a detailed and comprehensive description of the search for New Physics at the Large Hadron Collider (LHC) in the mono-jet final state, using the first 3.2 fb^-1 of data collected at the centre of mass energy of colliding protons of 13~TeV recorded in the ATLAS experiment at LHC.

The results are interpreted as limits in different theoretical contexts such as compressed supersymmetric models, theories that foresee extra-spatial dimensions and in the dark matter scenario. In the latter the limits are then compared with those obtained by other ATLAS analyses and by experiments based on completely different experimental techniques, highlighting the role of the mono-jet results in the context of dark matter searches.Lastly, a set of possible analysis improvements are proposed to reduce the main uncertainties that affect the signal region and to increase the discovery potential by further exploiting the information on the final state.

Nominated as an outstanding PhD thesis by the Sapienza University of Rome, Rome, Italy

Introduction.- The Standard Model.- Beyond the Standard Model.- The Dark Matter Paradigm.- Experimental Facilities.- Physics Objects.- The Mono-jet Analysis.- Mono-jet Versus All.- Mono-jet Analysis Improvements.- Conclusions.