Related papers: A Challenge to Lepton Universality in B Meson Deca…

Recently Georgi has discussed the possible existence of `Unparticles' describable by operators having non-integral scaling dimensions. With the interaction of these with the Standard Model (SM) particles being constrained only by gauge and…

Minimal extensions of the Standard Model that are motivated by grand unified theories or superstring models with an E_6 symmetry can naturally predict heavy neutrinos of Dirac or Majorana nature. Such heavy neutral leptons violate the de-…

A simultaneous analysis of the $B^+\to K^+\ell^+\ell^-$ and $B^0\to K^{*0}\ell^+\ell^-$ decays is performed to test muon-electron universality in two ranges of the square of the dilepton invariant mass, $q^2$. The measurement uses a sample…

Tests of lepton universality in $B^0\to K^0_S \ell^+ \ell^-$ and $B^+\to K^{*+} \ell^+ \ell^-$ decays where $\ell$ is either an electron or a muon are presented. The differential branching fractions of $B^0\to K^0_S e^+ e^-$ and $B^+\to…

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. In the present paper we investigate the decays of a Tau into three charged…

In the Standard Model (SM), the coupling of the electroweak gauge bosons to the leptons is lepton flavour universal. Tests of this property constitute sensitive probes for new physics models that violate lepton flavour universality. Recent…

We argue that the longitudinal lepton polarization and the forward-backward asymmetries in exclusive $B\to (K,K^*)\ell^+\ell^-$ decays are largely unaffected by the theoretical uncertainties in the long-distance contributions both induced…

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…

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…

This article reviews the current theoretical and experimental status of the field of muon decay and its potential to search for new physics beyond the Standard Model. The importance of rare muon processes with lepton flavor violation is…

Precision data on Kl3 and Kl2 decay rates and form factors allow us to perform significant tests of lepton universality and to constrain the strength of non-standard interactions. The present status of these tests and new physics searches…

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…

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…

The mass of an electroweakly charged lepton consists of the two components of electric and weak nature, and regardless of the difference in masses, all leptons have an equal charge, the same charge radius as well as an identical magnetic…

The electron and muon magnetic moments have played, and continue to play, important roles in testing the fundamental mathematical description of physical reality called the Standard Model of particle physics (SM). The electron magnetic…

The Standard Model (SM) of particle physics represents our most fundamental knowledge of elementary particles and their interactions. One of the cardinal properties of the SM which has been thoroughly studied during the past years is the…

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…

We investigate the constraint on the split fermions in extra dimensions by considering the universality of $W$ leptonic decays $W\to l_i \nu_i$, the charged lepton decays $l_i \ra l_j\nu_i\bar{\nu}_j$, and the lepton flavor violating…

The evidence for Lepton Flavour Universality (LFU) violation in semileptonic $B$-decays has been rising over the past few years. Relying on generic effective field theory (EFT) results, it has been shown that models addressing the…

The first test of lepton flavor universality between muons and electrons using $B^+ \to K^+\pi^+\pi^-\ell^+\ell^-$ ($\ell=e,\mu$) decays is presented. The measurement is performed with data from proton-proton collisions collected by the…