$\mu \to e$ flavour change is tightly constrained by $\mu \to e \gamma$, $\mu \to 3e$ and $\mu - e$ conversion on nuclei. Furthermore, the experimental sensitivity to these processes will improve by orders of magnitude in coming years.
This motivates the bottom-up, EFT study of what can be learned from these three processes, which will be described in this talk and allows to address...
The COMET experiment at J-PARC facility in JAPAN is designed to search for charged lepton flavour violation (cLFV), one of the most promising way of looking for physics beyond the Standard Model. Specifically, it will search for the coherent, neutrinoless conversion of a muon to an electron in the field of an aluminium nucleus, a process that is forbidden in the Standard Model and highly...
The Belle and Belle II experiments have collected a combined sample of $1.6~\mathrm{ab}^{-1}$ of $e^+e^-$ collision data at centre-of-mass energies near the $\Upsilon(nS)$ resonances. These data have constrained kinematics and low multiplicity, which allow searches for dark sector particles in the mass range from a few MeV to 10 GeV. Using a 365 fb$^{-1}$ sample collected by Belle II, we...
The NA62 experiment at CERN has collected a large sample of $K^+$ decays in flight during Run 1 in 2016-2018 and the ongoing Run 2 which started in 2021. Dedicated lepton-pair trigger lines have enabled a broad rare and forbidden decay programme. A review of searches for lepton flavour and number violating $K^+$ and $\pi^0$ decays with the NA62 lepton-pair dataset collected in 2016-2018 is...
The Standard Model predicts several rare Higgs boson processes, including decays into a Z boson and a photon, a low-mass lepton pair and a photon, or a meson and a photon. Observing these rare decays would offer new and complementary insights into the Higgs boson's coupling structure beyond the more commonly studied channels. In addition, searches for lepton-flavor-violating decays of the...
