PhD start seminar: Exotic decays of vector-like quarks in ATLAS

by Dr Elin Bergeås Kuutmann (Uppsala University), Mr Thomas Mathisen (Uppsala University)

Thursday 6 Dec 2018, 15:15 → 16:15 Europe/Stockholm

Abstract: In 2012 the discovery of the Higgs boson pieced together the Standard Model of Particle Physics. Since then, studies on the nature of the Higgs boson have been made, one example is understanding the so-called fine-tuning of the Higgs boson mass. Theoretical solutions to the fine-tuning problem exists such as supersymmetry and Composite Higgs Model. Both models predict the existence of additional particles which cancel the radiative corrections to the Higgs boson mass. Here the Composite Higgs Model is considered and how this leads to a prediction of Vector-Like Quarks (VLQ) is explained. More precisely focus is made on the Top-partner, a VLQ of charge +2/3 which in many scenarios decays to Wb, Ht and Zt. ATLAS and CMS have been conducting searches for the Top-partner. However, so far only considering decays to the known SM particles as stated above. By theory, the Composite Higgs model can predict additional pseudo-Nambu-Goldstone (pNGB) scalars. Here we construct such a extension and consider a new pNGB scalar S which will couple to the Top-partner, thus we add an exotic decay to the search.