Related papers: A Challenge to Lepton Universality in B Meson Deca…
Recent studies of novel four-body lepton number violating decays of $\tau$ leptons and neutral $B$ mesons are summarized and updated. These decays are assumed to be enhanced by the exchange of resonant Majorana neutrinos. It is shown that…
We analyse the violations of lepton-flavour universality in the ratios B(P -> l nu)/B(P -> l' nu) using a general effective theory approach, discussing various flavour-symmetry breaking patterns of physics beyond the SM. We find that in…
The number of leptons may or may not be a conserved quantity. The Standard Model predicts that it is (in perturbative processes), but there is the well known possibility that new physics violates lepton number in one or two units. The first…
We discuss proton and neutron decays involving three leptons in the final state. Some of these modes could constitute the dominant decay channel because they conserve lepton-flavor symmetries that are broken in all usually considered…
Many models for physics beyond the Standard Model predict lepton-flavour violating decays of charged leptons at a level which may become observable very soon. We investigate the decays of a Tau-lepton into three charged leptons (Tau ->…
Recent measurements have revealed a number of intriguing deviations from the Standard Model predictions in $B$ meson decays, in particular in observables testing lepton flavour universality. We review their experimental status and…
Experimental hints for lepton-flavor universality violation in the muon's magnetic moment as well as neutral- and charged-current $B$-meson decays require Standard-Model extensions by particles such as leptoquarks that generically lead to…
The "proton size puzzle" and the "muon anomalous moment problem" are incomplete descriptions of significant discrepancies of Standard Model calculations with experiments. What is particularly new is that the experiments and theory confront…
Since its discovery in the 1930s, the muon has played an important role in our quest to understand the sub-atomic theory of matter. The muon was the first second-generation standard-model particle to be discovered, and its decay has…
The rest masses of the stable mesons and baryons and the rest masses of their antiparticles, as well as the rest masses of the mu (+,-) and tau (+,-) leptons can be explained, within 1% accuracy, with the standing wave model, which uses…
The Standard Model (SM) of particle physics was finalized in its current form in the mid-1970s, and has been extensively tested and confirmed ever since, with the discovery of the Higgs boson in 2012 being the last missing piece. While no…
The pure lepton decay of the polarized muon is considered, accounting for a new tensor interaction which is outside of the Michel local interactions. This interaction leads to new energy distribution and polarization of the final charged…
The report reviews the measurements of the tau lepton parameters. The tau mass measurements at the KEDR detector as well as at the B-factories are considered in more details. The present limitations on the lepton universality are discussed.
Leptoquarks are ubiquitous in several extensions of the Standard Model and seem to be able to accommodate the universality-violation-driven $B$-meson-decay anomalies and the $(g-2)_\mu$ discrepancy interpreted as deviations from the…
Lepton flavor universality in the Standard Model and hints of its violation in neutral ($R_K$) and charged currents $(R_{D^{(*)}})$ in $B$ decays are presented. We discuss model independent features as well as several leptoquark scenarios…
This Resource Letter provides a guide to literature on the Standard Model of elementary particles and possible extensions. In the successful theory of quarks and leptons and their interactions, important questions remain, such as the…
The study of muon properties and decays played a crucial role in the early years of particle physics and contributed over decades to build and consolidate the Standard Model. At present, searches for muon decays beyond the Standard Model…
Model independent tests for symmetry violations in tau decays are important for determining whether the tau lepton is elementary or, instead, macroscopic. Such tests are also significant steps towards resolving the outstanding "e - mu -…
In view of recent experimental indications of violations of Lepton Flavor Universality (LFU) in $B$ decays, we analyze constraints and implications of LFU interactions, both using an effective theory approach, and an explicit dynamical…
We address the anomalies in the semi leptonic decays of $B$ mesons in a warped custodial framework. Two possible solutions of lepton non-universality are discussed: A) The muon singlets couple non-universally to NP and B) The…