Top quarks

Image removed.


With my group I focus on studying the properties of top quarks, the heaviest known fermions (by far! Their mass is about 170 times that of the proton). They are the only case of quark which decays into lighter particles before forming a bound state, which allows us to study fundamental strong force fermions as a unique case. 

Coupling with bottom quarks and quark mixing matrix: with my PhD student Valentina we are measuring the intensity of the top quark decaying into bottom quarks, their closest partners in the Standard Model. It is expected that top quarks decay only into bottom quarks: if this were not to be the case, it would be a major discovery and an indication of additional, unknown particles mixing with the Standard Model quarks.

Top quark pair production cross-section: with my PhD student Luca and in collaboration with colleagues at the Niels Bohr Institute in Copenhagen we are measuring how many times a pair of top quarks is produced at the LHC, as a function of many kinematic variables  (energy, velocity of electrons and muons produced in their decays). This is needed to further our understanding of how the Strong Force works.

b-tagging: as top quarks decays (almost?) always into b quarks, Valentina is also very busy measuring the efficiency of algorithms which are able to identify b quarks in jets of particles at the LHC. We developed and brought to fruition a method which was an old idea, lying there abandoned by ATLAS (the pt-rel method)

ttH: in the past I have also worked actively and for long on the search for the production of Higgs bosons with top quarks.  Top quarks, as they are so much heavier than all other fermions, probably play a special role in coupling with the Higgs boson, which originates in the mass mechanism of the Standard Model.  My plan for this was selected and granted a fellowship and money by the MIUR programma d’eccellenza “R.L.Montalcini”

muon trigger: I have also worked on the "trigger" system of ATLAS, which means that fast electronics is able to identify rare events with specific features (in my case muons of high energy) out of events happening 40 million times in a second. I have focused on the time alignment of the first level of the ATLAS muon trigger.

Image removed.

Image removed.