Related papers: Leptons and QCD
Inspired by the relation between the hadronic decay of the tau lepton and the electron-positron annihilation into hadrons, we derive new tests of perturbative QCD. We design a set of commensurate scale relations to test the self-consistency…
The evaluation, systematic analysis and numerical study of the semileptonic $\tau$-lepton decays with two mesons in the final state has been made in the frame of the standard model extended by right handed neutrinos. In the analysis,…
Tau decays into hadrons foresee the study of the hadronization of vector and axial-vector QCD currents, yielding relevant information on the dynamics of the resonances entering into the processes. We analyse tau -> (3 pion) nu_tau decays…
Following updates in the compilation of $e^+e^-\rightarrow{\rm hadrons}$ data, this work presents re-evaluations of the hadronic vacuum polarisation contributions to the anomalous magnetic moment of the electron ($a_e$), muon ($a_\mu$) and…
Precise measurements of magnetic and electric dipole moments are important tests of the Standard Model and beyond Standard Model physics, particularly for the electron and the muon. However, the situation presents distinctive challenges…
The mass of the $\tau$-lepton has been measured in the decay modes $\tau \to 3\pi \nu_\tau$ and $\tau \to 3\pi \pi^0\nu_\tau$ using a pseudomass technique. The preliminary result is $1776.71\pm 0.25 {(stat)} \pm 0.62 {(syst)}$ MeV. The…
The \tau \to (a_1 h)^- \nu_{\tau} decays of the \tau-lepton are studied using the method of phenomenological chiral Lagrangians. The expression of weak hadronic currents between pseudoscalar and axial-vector meson states is obtained.…
Analytic formulae are given for order alpha_s perturbative QCD corrections to the double differential distribution of the tau lepton energy and the invariant mass of the tau + antineutrino system in semileptonic decays of the bottom quark.…
We perform a global analysis of exclusive hadronic tau decays into one and two mesons using the low-energy limit of the Standard Model Effective Field Theory up to dimension six, assuming left-handed neutrinos. A controlled theoretical…
Within our present knowledge, the tau is the heaviest lepton and the only one decaying into hadrons, a fact that makes it the source of a very rich phenomenology. It represents the third family of leptons in the Standard Model, a feature…
The four-loop determination of the strong coupling from fully inclusive observables is reviewed. Special attention is given to the low-energy measurement extracted from the hadronic $\tau$ decay width. A recent exhaustive analysis of the…
The mass of the $\tau$ lepton has been measured in the decay mode $\tau \to 3\pi \nu_\tau$ using a pseudomass technique. The result obtained from $414 \mathrm{fb}^{-1}$ of data collected with the Belle detector is $M_\tau = (1776.61\pm 0.13…
Improved values for the two- and three-loop mass-dependent QED contributions to the anomalous magnetic moments of the electron, muon, and tau lepton are presented. The Standard Model prediction for the electron (g-2) is compared with its…
A technique to sum up the regular corrections appearing under the analytic continuation from the spacelike momentum region to the timelike one is proposed. A perturbative part of the inclusive semileptonic decay width of the tau-lepton in…
The angular asymmetry in decays of polarized muons and tau leptons is discussed. Both the standard $V-A$ Fermi model and the general parameterization via Michel parameters are considered. Numerical importance of contributions suppressed by…
We make use of recent accurate results obtained for the pion and kaon vector form factors within a chiral unitary approach in order to calculate the decay widths of the $\tau$ lepton to these mesons and also to evaluate the contribution of…
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.
Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order alpha_s^4 for the cross section of electron-positron annihilation into hadrons and for the decay rates of the Z-boson and…
The tau lepton lifetime is measured with the L3 detector at LEP using the complete data taken at centre-of-mass energies around the Z pole resulting in tau_tau = 293.2 +/- 2.0 (stat) +/- 1.5 (syst) fs. The comparison of this result with the…
The structure of the form factors stemmed from the hadronization of QCD currents in the energy region of the resonances can be explored through the analyses of exclusive hadronic decays of the tau lepton. I give a short review on the later…