The Standard Model (SM) is the theory describing Matter. This model is very predictive and has been tested thoroughly. However, it fails to explain cosmological puzzles as Dark Matter and the Matter-Antimatter imbalance. Several models exist that claim to better describe Matter: they are named New Physics (NP). There exist two ways to test NP. One can either look for particles in-existent in the SM, or more subtly, look for indirect effects of NP on specific observables.
The research I propose uses the indirect approach to constrain NP models. It has the potential to rule out some models, or on the contrary to discover NP via the observation of an effect impossible within the SM. Rare decays of B mesons allow for very precise predictions in the SM and there exist several observables for which the SM predictions sensibly differ from those of NP models. Thus rare B decays are ideally suited to test NP. In this project I propose to measure the branching fractions of the Bs and B0 into two muons, as well as to perform an angular analysis of the B0->K*mumu and Bs->Phimumu decays. The first subject has a high potential to constrain or discover NP. The other two subjects also have a large sensitivity to NP and have the further advantage to be complementary to the first subject since they probe for different types of models.
The proposed research is timely. The study of the Bs->mumu decay is indeed the most significant result of the LHC so far. Moreover, the angular study of B0->K*mumu is currently lacking statistics at any experiments but LHCb will be able to provide a unique result in the next years. Finally, the study of the Bs->Phimumu is less advanced but it recently raised a lot of attention from theorists who demonstrated its high potential to constrain NP.
The Cavendish Laboratory is perfect to undertake this research. My proposal extends indeed the work initiated at Cambridge on B0->K*mumu, while it brings new topics of study with Bs->mumu and Bs->Phimumu.
Fields of science
Call for proposal
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