Related papers: A Challenge to Lepton Universality in B Meson Deca…
In this paper, we consider the Standard Model (SM) with one family of vector-like (VL) leptons, which couple to all three families of the SM leptons. We study the constraints on this model coming from the heavy charged lepton mass bound,…
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…
We search for lepton-flavor-violating tau decays into three leptons (electron or muon) using 535 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No evidence for these decays is observed and we…
Fundamental symmetry tests with neutrons can provide unique information about whatever will be the new Standard Model of fundamental interactions. I review two aspects of this possibility: searches for the permanent electric dipole moment…
Very compelling deviations in the recently observed lepton nonuniversality observables $\big (R_{D^{(*)}}, R_{K^{(*)}}, R_{J/\psi} \big )$ of semileptonic $B$ meson decays from their Standard Model predictions hint towards the presence of…
In the framework of the Standard Model we present predictions for partial widths, double and single differential distributions, and forward--backward lepton asymmetries for four-leptonic decays $B^- \to \mu^+\mu^- {\bar \nu}_e\, e^-$, $B^-…
We report on the first searches for lepton flavour violating $\tau^-$ decays at a hadron collider. These include searches for the lepton flavour violating decay $\tau^-\to \mu^+\mu^-\mu^-$ and the lepton flavour and baryon number violating…
Deviations from the standard model prediction have been observed in several leptonic and semileptonic $B$ meson decays to $\tau\nu$ final states mediated via $b \to u$ and $b \to c$ charged current interactions. The measured value of ratio…
The large samples of tau decays available from CLEO and the four LEP experiment have resulted in new, precise measurements of the leptonic branching ratios of the $\tau$. The experimental techniques to obtain these results are reviewed with…
A next-generation rare pion decay experiment, PIONEER, is strongly motivated by several inconsistencies between Standard Model (SM) predictions and data pointing towards the potential violation of lepton flavor universality. It will probe…
We present a comprehensive update of the bounds on R-Parity violating supersymmetric couplings from lepton-flavour- and lepton-number-violating decay processes. We consider tau and mu decays as well as leptonic and semi-leptonic decays of…
The di-leptons and di-neutrinos observed in the final states of flavor-changing neutral b decays provide an ideal platform for probing physics beyond the standard model. Although the latest measurements of $R_{K^{(*)}}$ agree well with the…
This is a review of new results on the Tau lepton. The lifetime has been measured with improved precision, allowing the test of lepton universality to 0.2% level. There are several new measurements of the branching ratios for the hadronic…
Longitudinal lepton polarization asymmetry in B_q -> l l (q = d, s$ and l = e, mu, tau) decays is investigated. The analysis is done in a general manner by using the effective operators approach. It is shown that the longitudinal lepton…
This Fifth International WEIN Symposium is devoted to physics beyond the standard model. This talk is about tau lepton physics, but I begin with the question: do we know how to find new physics in the world of elementary particles? This…
Leptonic rare decays of $B^0_{s,d}$ mesons offer a powerful tool to search for physics beyond the Standard Model. The $B^0_{s}\to\mu^+\mu^-$ decay has been observed at the Large Hadron Collider and the first measurement of the effective…
The recent measurements on $R_D$, $R_{D^*}$ and $R_{J/\psi}$ by three pioneering experiments, BaBar, Belle and LHCb, indicate that the notion of lepton flavour universality is violated in the weak charged-current processes, mediated through…
Recent CLEO results on the search for CP violation in decays of B and D mesons and tau lepton are reviewed. New data on ``wrong-sign'' D decays and B to K(*)l+l-$ FCNC transitions are presented. As possible Standard Model contribution to…
While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in $b\to s\ell^{+}\ell^{-}$ and $b\to c\ell\nu$. In this context,…
The measurements of the ratios $R_{K^{(*)}}$ along with $R_{D^{(*)}}$ hint towards lepton flavor non universality which is in disagreement with the standard model. In this work, we reanalyze the four new physics models, which are widely…