Conveners
WG4: Muon Physics: CLFV part-I
- Yuri Oksuzian ()
WG4: Muon Physics: CLFV part-II
- Matthew Solt (University of Virginia)
WG4: Muon Physics: g-2: part I
- Simon Corrodi (Argonne)
WG4: Muon Physics: Colliders
- Yuri Oksuzian (Argonne)
WG4: Muon Physics: Future experiments
- Yuki Fujii (Monash University)
WG4: Muon Physics: g-2 part-II
- Gavin Hesketh (UCL)
We report on the MEG II experiment, a search for the charged lepton flavor violating (CLFV) decay $\mu^{+} \rightarrow e^{+} \gamma$. The experiment is designed to improve upon the previous most sensitive search, done by the MEG experiment, by an order of magnitude: a sensitivity of $4.2 \cdot 10^{−13} \rightarrow 6 \cdot 10^{−14}$ at the 90% confidence level. The positron and photon...
Being an accidental symmetry in the Standard Model (SM), the conservation of lepton flavour is violated in many extensions of the SM. There is a global effort to search for lepton flavour violation (LFV) at high intensity muon sources to which the upcoming Mu3e experiment at the Paul Scherrer Institute (PSI) will contribute.
The Mu3e Collaboration aims to perform a background-free search...
The Mu2e experiment, currently under construction at Fermilab, will search for the neutrinoless conversion of a muon into an electron in the field of an aluminum nucleus. A clear signature of this charged lepton flavor violating two-body process is given by the monoenergetic conversion electron of 104.97 MeV produced in the final state. The experimental apparatus consists of an intense pulsed...
The AlCap experiment recently published its first results on the yields and energy spectra of heavy particles emitted after the nuclear muon capture process. These detailed measurements quantify an important hit background to the Mu2e and COMET experiments, which will search for charged lepton flavor violation. These results greatly expand the literature in this area with first measurements on...
The one of an experiment to search for the charged lepton flavor violating process, muon-electron conversion in a nuclear field , DeeMe, is being prepared at the J-PARC MLF H-line in Japan. This experiment utilizes a pulsed proton beam from the Rapid Cycle Synchrotron (RCS). A graphite target is bombarded with a pulsed proton beam and negative pion production and pion-in-flight-decay to...
Muon to electron conversion, an example of charged lepton flavour violation (CLFV), provides a clear experimental probe into new physics beyond the Standard Model. The COMET experiment at J-PARC will use the highest intensity muon beam to search for muon to electron conversion using a staged approach, with sensitivity levels in reach of many new physics models. With a single event sensitivity...
The hadronic vacuum polarization (HVP) is one of the main contributors to the total uncertainty in the theoretical prediction of the muon $g - 2$. The HVP term is historically obtained from a data-driven calculation based on a dispersive approach from time-like processes. To improve the theoretical prediction of HVP, in parallel to the lattice communities' effort to obtain HVP by space-like...
The MUonE experiment aims at an independent and competitive determination of the leading hadronic contribution to the muon anomalous magnetic moment $a_\mu = (g_\mu -2)/2$, based on an alternative method, complementary to the existing ones. It relies on the measurement of the shape of the $\mu e$ elastic scattering cross section, with unprecedented precision, which can be obtained at CERN by...
First results from the Fermilab Muon $g-2$ experiment were announced in 2021. The muon’s anomalous magnetic moment $a_{\mu}$ was measured to an unprecedented $460 \text{ ppb}$ precision, and the result is in agreement with the previous Brookhaven National Lab measurement. The $4.2 \sigma$ tension between the combined experimental result and the Standard Model theoretical prediction suggests...
The NA62 experiment at CERN collected world's largest dataset of charged kaon decays in 2016-2018, leading to the first observation of the ultra-rare K+ --> pi+ nu nu decay based on 20 candidates. Dedicated trigger lines were employed for collection of di-lepton final states, which allowed establishing stringent upper limits on the rates lepton flavor and lepton number violating kaon decays....
The growing evidence of lepton-flavour-universality violation in B-meson decays is one of the most interesting hints for physics beyond the Standard Model that may be reachable at the Large Hadron Collider. In addition, the observation of lepton flavor violation (LVF) would be a smoking gun for the presence of physics beyond the Standard Model Consequently, a broad program of measurements and...
The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is 6×1035 cm−2s−1 and the Belle II experiment aims to ultimately record 50 ab−1 of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure the...
Tests of lepton flavour universality are particularly sensitive to the presence of physics beyond the Standard Model. Recent results and future prospects with semileptonic and rare heavy flavour decays at the LHCb experiment are presented.
Muon to electron conversion in a muonic atom is an excellent laboratory to search for
charged lepton flavor violation (CLFV). Its discovery would be a clear signal of physics beyond the
Standard Model (BSM). In order to further improve the experiments by an additional factor of 100 in sensitivity beyond the current generation ones and study
potential signals, the use of a Fixed-Field...
We propose an evolution of the Mu2e experiment, called Mu2e-II, that would leverage advances in detector technology and utilize the increased proton intensity provided by the Fermilab PIP-II upgrade to improve the sensitivity for neutrinoless muon-to-electron conversion by one order of magnitude beyond the Mu2e experiment, providing the deepest probe of charged lepton flavor violation in the...
The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. The scenario where dark matter originates from thermal contact with familiar matter in the early Universe requires the DM mass to lie within about an MeV to 100 TeV. Considerable experimental attention has been given to exploring Weakly Interacting Massive Particles in the upper end of...
The observation of a non-zero permanent electric dipole moment (EDM) of an elementary particle would break both parity and time-reversal symmetries, implying the violation of charge-parity (CP) symmetry under CPT invariance. The Standard Model (SM) predicts subatomic particle EDMs which are so small as to be out of reach of current experiments, such that any observation of a non-zero EDM would...
The muon g-2/EDM experiment at J-PARC (E34) aims to measure muon g-2 and EDM with a low-emittance muon beam realized by the acceleration of thermal muons. Together with other novel techniques, the experiment measures muon g-2 in a different approach from FNAL. The technical design of the experiment has been completed, and the budget is being requested to start the data taking in 2027. In the...
Permanent electric dipole moments (EDMs) are excellent probes of physics beyond the Standard Model. Recently, the muon EDM has been of particular interest due to the tensions in the magnetic anomaly of the muon and the electron and hints of lepton-flavor universality violation in B-meson decays. At PSI, we proposed a dedicated muon EDM search experiment using the frozen-spin technique. In this...