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

It has been recently proposed that neutrino mass could originate from Yukawa interactions of leptons with new colored particles. This raises the interesting possibility of testing mass generation through copious production of those…

Motivated by the measurements of $b\to s\ell^+\ell^-$ transitions, including $R(K)$ and $R(K^*)$, we examine lepton flavour (universality) violation in $B$ decays and its connections to $\mu\to e\gamma$ in generic leptoquark models.…

The electric and magnetic dipole moments of the electron and of the muon provide stringent tests of the Standard Model and sensitive probes of new physics. By contrast, the corresponding dipole moments of the $\tau$ lepton remain weakly…

In the Standard Model, the three charged lepton are identical copies of each other, apart from mass differences. Experimental tests of this feature in decays of semileptonic b hadrons, such as $B\rightarrow D^* \tau\ nu$, are highly…

High energy, high luminosity, future lepton colliders, circular or linear, may possibly give us hint about fundamental laws of Nature governing at very short distances and very short time intervals, the same which have brought our Universe…

Lattice theory is used to explain the rest masses of the stable mesons and baryons and their spin. From the mass of the charged pi-mesons follows the mass of the muons. From the mass of the muons follows the mass of the electron. We do not…

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…

In the Standard Model (SM), the rare transitions where a bottom quark decays into a strange quark and a pair of light leptons exhibit a potential sensitivity to physics beyond the SM. In addition, the SM embeds Lepton Flavour Universality…

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…

Since its inception, no decisive departure from the predictions of Standard Model (SM) has been reported. But recently various experiments have observed few hints of possible departure from SM predictions in lepton flavor universality…

A test of lepton universality between muons and electrons is performed using $B^+\to K^+\ell^+\ell^-$ decays (where $\ell$ = $e$, $\mu$), in the dilepton invariant-mass-squared region above 14.3 GeV$^2/c^4$. The data used for the…

Recent Standard Model predictions for the anomalous magnetic moments of the electron, muon and tau lepton are reviewed and compared to the latest experimental values.

We interpret the recent hints for lepton flavor universality violation in rare $B$ meson decays. Based on a model-independent effective Hamiltonian approach, we determine regions of new physics parameter space that give a good description…

A search for compositeness of electrons and muons is presented using a data sample of proton-proton collisions at a center-of-mass energy of sqrt(s) = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated…

The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium ($M = \mu^+ e^-$) can be used as an ideal…

The fundamental description of nature, beyond the Standard Model (SM), may include heavy neutrinos that mix and thus allow processes in which lepton flavor is not preserved. We investigate the impact of charged currents that couple heavy…

A recent analysis of the LEP data shows an interesting deviation from lepton universality in W boson decays. An excess at the level of 2.8 sigma is found in the tau mode branching ratio with respect to the other two modes. It is suggested…

We show that lepton number violating muon decays, \mu^+ -> e^+ + \nu_e-bar + \nu_i-bar (i=e, \mu or \tau), can consistently explain the neutrino anomaly reported by the LSND experiment. Two effective operators in the Standard Model are…

The "precision" frontier, which is closely related to the "intensity" frontier, provides a complementary path to the discovery of physics beyond the Standard Model. Several examples of discoveries that would change our view of the physical…

We present a measurement of the ratio $R_\mu = \mathcal{B}(\tau^-\to \mu^-\bar\nu_\mu\nu_\tau) / \mathcal{B}(\tau^-\to e^-\bar\nu_e\nu_\tau)$ of branching fractions $\mathcal{B}$ of the $\tau$ lepton decaying to muons or electrons using…