Related papers: Charged Scalar Particles and $\tau$ Leptonic Decay
An extension of the Zee model involving a light right handed neutrino, nu_R is considered. We update constraints on couplings between the bilepton scalar, the active neutrinos, nu_R and the charged leptons. We find that the most stringent…
We study a renormalizable theory that includes a heavy weak-singlet vectorlike lepton, $\tau^\prime$, that decays into a pseudoscalar boson and a tau lepton. We show that this can be the dominant decay mode of $\tau^\prime$ provided the…
We analyze the recent experimental evidence for an excess of $\tau$-lepton production in several exclusive semileptonic $B$-meson decays in the context of two-Higgs-doublet models. These decay modes are sensitive to the exchange of charged…
We consider a Standard Model extension by a heavy charged scalar gauged only under the $U_{Y}(1)$ weak hypercharge gauge group. Such an extension, being gauge invariant with respect to the SM gauge group, is a simple special case of the…
Purely leptonic $B$ meson decays provide unique probes for physics Beyond the Standard Model. We study the impact of a scalar leptoquark, $S_1$, on $B \to \mu \bar\nu$ decay. We find that, for $m_{S_1}\sim 1$ TeV, the $S_1$ leptoquark can…
The Standard Model (SM) is augmented with a $\mathrm{U}(1)_{B-3L_\mu} $ gauge symmetry spontaneously broken above the TeV scale when an SM-singlet scalar condenses. Scalar leptoquarks $S_{1(3)} = (\overline{\mathbf{3}},\, \mathbf{1}…
In extensions of the standard model, light scalar particles are often possible because of symmetry considerations. We study the decay of the Z boson into such particles. In particular, we consider for illustration the scalar sector of a…
We calculate new contributions to the $K_L\to\pi^0\nu\bar\nu$ decay in models where neutrino Majorana masses require an extension of the scalar sector. First, we study a model where the neutrino mass is induced by the vacuum expectation…
While the $S_3$ scalar leptoquark presents a possible tree-level explanation of the $b \to s \ell \ell$ flavour anomalies, it suffers from two conceptual problems which are often disregarded by model-builders. Firstly, the quantum numbers…
Dark particles with lepton-flavor-violating couplings to the tau lepton can induce rare neutrinoless $\tau$ decays with large final state multiplicities. We study models where transitions of the type $\tau^\pm\to \ell^\pm\,\phi$, with…
We review possible impact of beyond Standard Model physics in the third generation leptonic and semileptonic B decays.
We explore the phenomenology of an $SU(2)$-singlet doubly charged scalar at the high and low energy frontier. Such a particle is predicted in different new physics models, like left-right symmetric models or the Zee-Babu model. Nonetheless,…
We introduce a physical scalar sector in a SU(2)xU(1) electroweak theory in which the gauge group is realized non linearly. By invoking theoretical as well as experimental constraints, we build a phenomenologically viable model in which a…
We consider the version of the Zee model where both Higgs doublets couple to leptons. Within this framework we study charged Higgs decays. We focus on a model with minimal number of parameters consistent with experimental neutrino data.…
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 ->…
Semileptonic exclusive tau decays in the Standard Model are reviewed. As it is well-known, they are a privileged arena to learn about low-energy hadronization. They also allow for a number of clean new physics tests, which have attracted…
In a recent paper, 8 semileptonic parameters were defined to specify the most general Lorentz-invariant spin correlation functions for 2-body tau decays. These parameters can be used to search for anomalous longitudinal-versus transverse…
We discuss the theory and phenomenology of decays of a leptophobic $U(1)_\X$ gauge boson $X$, such as has been proposed to explain the alleged deviations of $R_b$ and $R_c$ from standard model predictions. If the scalars involved in the…
The branching fractions of $\tau$ lepton decays with the production of strange scalar mesons both in the ground and first radially excited states $\tau \to \nu_\tau [K^*_0(700), K^*_0(1430)]$ and $\tau \to \nu_\tau [K^*_0(700)\pi,…
We re-examine the question of radiative symmetry breaking in the standard model in the presence of right-chiral neutrinos and a minimally enlarged scalar sector. We demonstrate that, with these extra ingredients, the hypothesis of…