Iacopo Vivarelli
Professor (Experimental Particle Physics Research Group)

Research

I have spent the last few years (since 2010, when LHC has started collecting data) focusing on searches for signals from supersymmetric particles. The Standard Model of particle physics does not give a complete description of our Universe, as, for example, it does not explain dark matter. A supersymmetric extension of the Standard Model might actually explain dark matter while fixing problems related to perturbative corrections to the Higgs mass.

There are good theorethical reasons to expect the supersymmetric partners of the bottom and top quark to have relatively small masses, and therefore to be produced abundantly at the LHC. My research has focused on the search of such partners, the so-called stop and sbottom. Unfortunately, so far we failed in observing a signal from these new particles. This has led us to derive what we call 'exclusion limits'. We basically answer the following question: what can I say about the mass of the new particles given the fact that I have observed no signal from them? The answer is expressed by the plot below. On the x-axis one finds the mass of the supersymmetric partner of the top quark, on the y-axis one finds instead the mass of the dark matter candidate particle. All the regions that are coloured are excluded by the LHC data collected by the ATLAS experiment in 2012.