“The flavour of Dark Matter – A search for Dark Matter in association with a Higgs boson decaying to bottom quarks with the ATLAS detector”
Veronica Fabiani, promovenda aan het Nikhef, verdedigt haar proefschrift vrijdag 5 juni 2020 online aan de Radboud Universiteit te Nijmegen.
“Have you ever played hide-and-seek? It may be a long shot but I believe this game works a bit like the search for Dark Matter at the Large Hadron Collider (LHC). The seeker can win the game only if all the hidden players have been found. Catching the majority of them is not enough. Well, when a proton-proton collision occurs at the LHC, a large number of particles is produced, all of them giving rise to a different signals in our detectors. Only after all the visible particles have been recognised, we can tell whether something is still missing. . . or rather it is invisible. We don’t know much about Dark Matter, but one thing that we know is that it seems to interact very weakly with “ordinary” matter, i.e. all the matter described by the Standard Model (SM) of particle physics. Therefore, if we were able to produce Dark Matter at the LHC, we wouldn’t see it directly because it would not leave any signal in the detector. At the LHC, the energy imbalance caused by the particles escaping our detection is called “missing energy” (MET). If we want to select a Dark Matter signal we therefore need to require the presence of an additional measurable object X. Here it is: the MET + X final state. The discovery of the Higgs boson in 2012 by the ATLAS and CMS experiments opened up a new challenge: looking for MET + Higgs events. Since the Higgs boson decays mostly to a pair of bottom quarks b, it is natural to probe the MET + H(bb), also called monoHbb, signature. In this thesis, I present the results of the monoHbb search performed during Run 2 of the LHC with the ATLAS detector. One of the most challenging aspects of this analysis is the ability to identify the flavour of the Higgs boson’s decay products. Therefore a special highlight is dedicated to the study of optimised flavour tagging algorithms and new reconstruction techniques that can help us identifying the presence of b-quarks, especially at very high energies. Unfortunately, no sign of Dark Matter was found in the data collected by the ATLAS detector during 2015, 2016 and 2017. Nevertheless, not every stone has been turned so we cannot exclude that Dark Matter is still hiding somewhere…this means that we have a new exciting hide-and-seek game to play during Run 3 of the LHC!”
“The flavour of Dark Matter – A search for Dark Matter in association with a Higgs boson decaying to bottom quarks with the ATLAS detector” (pdf)
De promotie vindt plaats online om 11.00. Het is mogelijk de promotie te volgen via een livestream.
Promotoren: prof. dr. N. de Groot
Co-promotor: dr. F. Filthaut
contact: Veronica Fabiani