Development of the NA62 Detector and search for New Physics with kaon decays

Nowadays High Energy Physics and Cosmology are more interconnected than ever: the former and its Standard Model (SM) are powerful tools to understand the latter, while the latter currently gives the only indications that there is new physics beyond the SM, i.e. the existence of Dark Matter and the matter-antimatter asymmetry in the Universe. Measurements related to very rare decays are being pursued by several experiments, since searches for new physics in forbidden or heavily suppressed phenomena have access to higher energy scales than the direct searches for new particles. NA62 is a fixed target experiment at CERN, now in its final stage of development. Its aim is to measure ultra rare decays of kaon particles, which fall in the category of processes described above and have also the advantage of a very accurate theoretical prediction within the Standard Model. This is a unique opportunity to search for new physics and be able to distinguish between several proposed models involving new physical processes.
Addressing measurements of rare processes is, therefore, rewarding, but it represents a significant challenge. The need to generate a huge amount of processes to achieve a large statistics - kaon decays in this case - conflicts with the need to reject almost all of them to collect the few interesting ones. This is intrinsically unavoidable, and challenging both in the production and in the rejection phase. Besides, it is also necessary to ensure that the statistical quality of the measurement is not spoiled by detector and systematic effect.

Cosmology and Particle Physics are cascade tools to achieve a better understanding of Nature. On the other hand, developing new detectors, with all the effort needed to understand the hidden details, usually gives insights in Nature that are rewarding by themselves, besides being useful to progress in research.
I plan to exploit my expertise in designing, building and operating detectors to ensure that the final performance of the experimental setup will be the best to achieve the target accuracy. Part of this task is to understand the detector itself, and this can be done by means of simulation and analysis software; I have extensive expertise also in this area, being the primary author of the NA62 software.

The CEDAR detector, which is being developed by UK institutions, among which Birmingham is the leader, will be crucial to suppress one of the instrumental effects that could prevent the success of the experiment. Identifying kaons at 50MHz rate in a GHz hadron beam mainly composed of pions and protons is a technologically challenging but essential task. The identification will in fact minimise backgrounds due to interactions of the beam with the material of the detectors, which otherwise could spoil the measurements.

Once the construction and testing will be finished, and the understanding of the subtleties of the response of the instrumentation will be good enough to reject the overwhelming background affecting the foreseen measurements, I plan to lead the analysis of the data. I will focus on the study of background and systematic effects, the two most important issues. The systematic studies will examine subtle detector effects, like for example the impact on the measurement of non-gaussian tails in the particle reconstruction. It will also be necessary to study most of the background channels in detail, to be able to reproduce them in the simulation and to efficiently reject them. At this stage, joining the expertise on detectors and data analysis will be crucial to the success of a such challenging project.

These measurements of kaon rare decays will put tight constraints on possible new physics processes, or reveal new ones. By that time, the LHC might have found evidence for new particles and the rare kaon decays will then be essential to study the structure of new physics.