The NA62 experiment at CERN took data in 2016–2018 with the main goal of measuring the K+ → π+νν ̄ decay. The NA62 dataset is also exploited to search for light feebly interacting particles produced in kaon decays. Searches for K+ → e+N, K+ → μ+N and K+ → μ+νX decays, where N and X are massive invisible particles, are performed by NA62. The N particle is assumed to be a heavy neutral lepton,...
A new search for the electroweak production of supersymmetric particles decaying into two leptons with missing transverse momentum is presented. Two simplified models are considered: direct pair production of sleptons decaying into the lightest neutralinos through leptons of the Standard Model (SM) and direct pair production of the lightest charginos decaying into the lightest neutralinos...
This talk presents the results of a direct search for lepton-flavour-violating decays of the Higgs boson into e tau and mu tau final states with the ATLAS detector at the LHC with Run 2 data. Both leptonically and hadronically decaying tau leptons are included and two different background estimation techniques are employed: a MC-template method, based on data-corrected simulation samples, and...
The ratios $R(D^{(*)})$ are defined as the $\tau/\mu$ ratio of the branching fractions of semileptonic $B \to D^{(*)}$ decays. They are a powerful test of Lepton Flavour Universality (LFU) and are determined by the hadronic Form Factors (FFs) describing the $B \to D^{(*)}$ decays. Through the novel Dispersive Matrix (DM) approach, we describe these FFs without assumptions on their functional...
During the last 15 years the "Radiative Corrections and Monte Carlo Generators for Low Energies" Working Group (Radio MontecarLow WG, see www.lnf.infn.it/wg/sighad/) has been providing valuable support to the development of radiative corrections and Monte Carlo generators for low energy $e^{+}e^{-}$ data and tau-lepton decays.
Its operation started in 2006 and proceeded until the last few...
Despite the many successes of the Standard Model of Particle Physics, there are still several physical observations that it cannot explain, such as matter-antimatter asymmetry, non-zero neutrino masses, and the existence of dark matter. To address these limitations, extensions to the Standard Model are necessary, and a search for electric dipole moments of leptons is a valuable test. The...
The search for charged Lepton Flavour Violation (cLFV) in muon decays is a sensitive probe to test the Standard Model at the intensity frontier. The MEG II and Mu3e experiments at the Paul Scherrer Institut are respectively designed to detect $\mu \to e \gamma$ and $\mu \to eee$ with an unprecedented accuracy. In addition, both experiments are sensitive to cLFV decays of a muon into an...
In the Muon EDM experiment in preparation at the Paul Scherrer Institute (PSI), an entrance detector is needed to trigger the storage mechanism if a muon with the right phase space is injected. A first detector prototype consists of a very thin (100 μm) plastic scintillator to trigger the arrival of a muon, and a long rectangular channel to ensure that the muon follows the desired trajectory...
At the Paul Scherrer Institute (PSI), we are setting up an experiment to search for the electric dipole moment of the muon (muEDM) using the frozen-spin technique. The discovery of a muEDM would indicate violation of charge conjugation parity symmetry and lepton flavor universality, beyond the Standard Model. The experiment aims to achieve a sensitivity of...
In a dedicated experiment at the Paul Scherrer Institute (PSI) [A. Adelmann et al., [arXiv:2102.08838][1] (2021)], the muEDM Collaboration seeks to implement, for the first time, the frozen-spin technique [F.J.M. Farley et al., [Phys. Rev. Lett., 93, 052001][2] (2004)$]$ in order to advance the search for the muon electric dipole moment (EDM) with an improved sensitivity...
At the Paul Scherrer Institute we are developing a high precision instrument to measure the electric dipole moment (EDM) of the muon. The salient feature of the experiment is the use of the frozen-spin method to suppress the anomalous precession of the muon spin, allowing for a sensitivity that cannot be achieved with conventional g-2 muon storage rings. With this technique, the expected...
In high energy particle physics scattering experiments, the precision of the reconstructed particle tracks can be fundamental. For this reason, a method for detecting the displacement of tracking detector modules is developed. The modules are silicon planes mounted on a frame and used in the MUonE project, which aims at a precision measurement of the scattering angle of elastic muon-electron...
The Mu2e experiment is currently being constructed at Fermilab to search for the neutrino-less conversion of negative muons into electrons in the field of an aluminum nucleus. The experiment aims at a sensitivity of four orders of magnitude higher than previous related experiments, which implies highly demanding accuracy requirements both in the design and during the operation. To achieve such...
