Related papers: Tau as a Probe for New Physics
Lorentz and CPT symmetry have been tested at high precision in numerous experiments. A general theoretical framework incorporating possible Lorentz and CPT violation in an extension of the standard model of particle physics has been…
The polarization of a top-quark can be sensitive to new physics beyond the standard model. We propose a novel method to measure top-quark polarization, based on the charged lepton energy fraction in top-quark decay, and illustrate the…
We study the five-body decays $\mu^- \to e^- e^+ e^- \nu_{\mu} \bar{\nu}_{e}$ and $\tau^- \to \ell^- \ell'^+\ell'^-\nu_{\tau}\bar{\nu}_{\ell}$ for $\ell, \ell'=e, \mu$ within the Standard Model (SM) and in a general effective field theory…
The implications of precision $Z$ and $W$-pole and neutral current data for testing the standard electroweak model, determining its parameters, and searching for new physics, are described.
We review the current status of precision electroweak measurements and the constraints they impose on new physics. We perform a model independent analysis using the STU-formalism of Ref. 1, and then discuss how the Z-pole data from LEP and…
Interactions between electrons in solids are often behind exciting novel effects such as ferromagnetism, antiferromagnetism and superconductivity. All these phenomena break away from the single-electron picture, instead having to take into…
The possibility off measuring for the first time neutrino-nuclei coherent scattering has been recently discussed by several experimental collaborations. It is shown that such a measurement may be very sensitive to non-standard interactions…
The discovery of a Z' and the measurement of Z' couplings to fermions are main tasks of future colliders. Here, the possibilities to measure Z' f \bar f couplings at an NLC operating below a Z' resonance are studied. In dependence on the…
The DONUT collaboration has observed four events in a hybrid emulsion spectrometer consistent with tau neutrino charged-current interactions. The resulting tau lepton is identified by its decay into a single charged particle. The expected…
$\tau$ leptons emitted in cascade decays of supersymmetric particles are polarized. The polarization may be exploited to determine spin and mixing properties of the neutralinos and stau particles involved.
We parameterize the non-universal couplings of t-t-Z and t-b-W in the electroweak chiral lagrangian approach, and examine the constraints on these parameters from the LEP data. We also study how the SLC, Tevatron, LHC and NLC can improve…
This article summarizes recent developments in $B\to D^{(\ast)}\tau\nu$ decays. We explain how to extract the tau lepton's production properties from the kinematics of its decay products. The focus is on hadronic tau decays, which are most…
The low-energy approach to electric charge quantization predicts physics beyond the minimal standard model. A model-independent approach via effective Lagrangians is used examine the possible new physics, which may manifest itself…
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…
In recent times, several hints of lepton non-universality have been observed in semileptonic $B$ meson decays, both in the charged-current ($b \to c l \bar \nu_l$) and neutral-current ($b \to s ll $) transitions. Motivated by these…
Methods for obtaining additional sensitivities to Lorentz violation in the fermion sector of the Standard-Model Extension using gravitational couplings are discussed.
In this talk, a brief summary is given of the possibility of using neutral-kaon oscillations to bound CPT- and Lorentz-breaking parameters in an extension of the minimal standard model.
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-…
Analytic formulae for the one-loop order QCD corrections to the differential width of the semileptonic b decay are given with the tau polarization taken into account. Thence the polarization of tau is expressed by its energy and the…
In the present report, let us adress the issues related to simulation of decays for particle embodied in full production and decay chains of Monte Carlo programs set-up for experiments such as at LHC or LC. Both technical issues related to…