Unipi Team Leader: Prof. Francesco Forti, Dipartimento di Fisica 

I propose a measurement of the lepton flavour violating (LFV) tau -> lepton + gamma decay, where the lepton is a muon or an electron. This will be carried out at the University of Pisa (Italy) under the supervision of Prof. Francesco Forti.

Although highly successful, the Standard Model (SM) of particle physics does not completely describe all the phenomena we observe, such as the recent discovery of neutrino oscillations which violate lepton flavour conservation in the neutral sector.

Many scenarios have been advanced to extend the SM into a bigger picture; several of these models predict LFV to occur in the charged sector as well at measurable rates.

I will exploit the unprecedented data sample provided by the Belle II experiment at SuperKEKB to measure the tau -> lepton + gamma decay rate with a sensitivity of at least a factor of four greater than any previous measurement.

In order to achieve this result I will develop an advanced physics analysis, making full use of the characteristics of the state-of-the-art Belle II detector and incorporating modern techniques such as machine learning. I will use my experience in physics analysis, preparatory studies and detector performance measurements to make this possible.

The impact of a measurement of such sensitivity would be tremendous. A discovery of charged LFV would constitute an enormous breakthrough which would spark a new era of particle physics; a non-observation would instead place strong constraints on possible extensions of the SM and inform physics studies for the coming decade.

Coordinator:
UNIVERSITA DI PISA

Start date 1 June 2021
End date 31 May 2023
Project cost € 183 473,28 €
Project funding € 183 473,28 €
Unipi quota € 183 473,28€
Call title H2020-MSCA-IF-2020