The Belle and Belle II experiments have collected a $1.6~\mathrm{ab}^{-1}$ sample of $e^+e^-$ collision data at center-of-mass energies near the $\Upsilon(nS)$ resonances. We present searches for the decays $\tau \to \mu\gamma$, $\tau \to \ell\eta$, $\tau\to \ell\pi^0$, and $\tau^-\to \ell^-\alpha$, where $\ell = e$ or $\mu$ and $\alpha$ is an invisible scalar particle. In addition, we...
The Standard Model predicts several rare decay processes of the Higgs boson, including decay to a Z boson and a photon (H->Zgam), decay to a pair of muons (H->mumu), and decay to a pair of electrons (H->ee). The lepton-flavor-violating (LFV) decay of the Higgs boson, on the other hand, is forbidden in the Standard Model but allowed in new physics models. Search for rare and LFV decays of the...
The MUonE experiment, currently under preparation at CERN, aims to measure the running of the electromagnetic coupling $\alpha$ in the elastic $\mu e$ scattering process, from which the dominant hadronic contribution to the anomalous magnetic moment of the muon can be extracted. We present performance results from the Phase 1 MUonE test-beam campaign carried out in summer 2025 at the CERN SPS...
Ordinary Muon Capture (OMC) provides a unique experimental avenue to probe the β+ type nuclear responses essential for understanding double beta decays (DBDs) and astrophysical neutrino interactions. This study leverages high energy-resolution gamma-ray spectroscopy to meticulously identify transition channels in enriched and natural molybdenum. By utilizing high-purity germanium (HPGe)...
