Publications

Order by: publication date number of citations

• Lepton flavor violation with tau leptons

  Julian Heeck

  SciPost Phys. Proc. 17, 005 (2025) · published 23 July 2025 | Toggle abstract · pdf

  We review the status and importance of lepton flavor violation with tauons, focusing on overlooked flavor-breaking patterns as well as tau-flavor violation in nucleon decays.

• Electric and magnetic tau dipole moments revisited

  G. A. González-Sprinberg

  SciPost Phys. Proc. 17, 004 (2025) · published 23 July 2025 | Toggle abstract · pdf

  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 when dealing with the tau lepton due to its very short lifetime and relatively high mass. Here, we review the theoretical predictions and experimental measurements of both the anomalous magnetic and electric dipole moments of the tau lepton.

• Electromagnetic corrections in hadronic tau decays

  Jesús Alejandro Miranda Hernández

  SciPost Phys. Proc. 17, 003 (2025) · published 23 July 2025 | Toggle abstract · pdf

  We briefly review electromagnetic radiative corrections in semileptonic tau decays and their main applications.

• Monte Carlos for tau lepton - Standard Model and new physics signatures

  Zbigniew Was

  SciPost Phys. Proc. 17, 002 (2025) · published 23 July 2025 | Toggle abstract · pdf

  One of the purposes of High Energy accelerator experiments is confrontation of theory and measurements in ever new realms. Any new agreement extends theory applicability domain, any discrepancy hints to unexplained, calling for better calculations or new, deeper theory. Often one has to search for small contributions over large Standard Model background. Multidimensional signatures and complex background subtraction cuts imply that Monte Carlo techniques are indispensable. My talk included description of: KKMC Monte Carlo for $e^+e^- \to \tau^+\tau^- (n\gamma)$ (with $\tau$ decays), generation of additional lepton pairs of SM and New Physics, and contributions from anomalous magnetic and electric dipole moments.

• Tau lepton averages by the HFLAV group

  Alberto Lusiani

  SciPost Phys. Proc. 17, 001 (2025) · published 23 July 2025 | Toggle abstract · pdf

  We document some features of the preliminary draft of the tau lepton averages for the incoming HFLAV report. We include the tau mass and lifetime averages, and a fit of measurements of tau branching fraction measurements. Elaborations of these results provide lepton universality tests and determination of $|V_{us}|$ with tau measurements.

• Status of the MUonE experiment

  Riccardo N. Pilato

  SciPost Phys. Proc. 16, 034 (2025) · published 15 July 2025 | Toggle abstract · pdf

  The latest measurement of the muon g-2, recently announced at Fermilab, exhibits a 4.2$\sigma$ discrepancy from the Standard Model prediction. The hadronic contribution $a_{\mu}^{HLO}$ represents the main source of uncertainty on the theoretical prediction. The MUonE experiment proposes a novel approach to determine $a_{\mu}^{HLO}$ by measuring the effective electromagnetic coupling in the space-like region, via $\mu - e$ elastic scattering. The measurement is performed by scattering a 160 GeV muon beam, available at CERN, on atomic electrons of a low-Z target. A Test run on a reduced detector is planned in 2022, to validate this proposal. The status of the experiment in view of the Test run is presented.

• Status of Radio MonteCarLow and Strong2020 $e^+e^-$ database activities

  Graziano Venanzoni

  SciPost Phys. Proc. 16, 033 (2025) · published 15 July 2025 | Toggle abstract · pdf

  During the last 15 years the Radio MonteCarLow Working Group has been providing valuable support to the development of radiative corrections and Monte Carlo generators for low energy $e^+e^-$ data and $\tau$-lepton decays. While the working group has been operating for more than 15 years without a formal basis for funding, parts of our program have recently been included as a Joint Research Initiative in the group application of the European hadron physics community, STRONG2020, to the European Union, with a more specific goal of creating an annotated database for low-energy hadronic cross sections in $e^+e^-$ collisions. We will report on both these initiatives.

• New $\tau$-based evaluation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment

  Jesús Alejandro Miranda Hernández, Pablo Roig Garcés

  SciPost Phys. Proc. 16, 032 (2025) · published 15 July 2025 | Toggle abstract · pdf

  We revisit the radiative corrections to the $\tau^-\to\pi^-\pi^0\nu_\tau(\gamma)$ decays using Resonance Chiral Theory for the structure-dependent part. This channel is the most important one to understand the hadronic vacuum polarization piece of the muon g-2, which dominates the uncertainty of its data-driven prediction in the Standard Model. Using our results, the discrepancy between theory and experiment for this observable is reduced to $\sim2.2\sigma$.

• A continuum determination of the strong isospin-breaking contribution to the muon anomalous magnetic moment

  Kim Maltman, Christopher James, Randy Lewis

  SciPost Phys. Proc. 16, 031 (2025) · published 15 July 2025 | Toggle abstract · pdf

  First-principles lattice determinations of the Standard Model expectation for the leading order hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon have become sufficiently precise that further improvement requires including strong and electromagnetic isospin-breaking effects. We provide a continuum estimate of the strong isospin-breaking contribution, $a_\mu^{SIB}$, using $SU(3)$ chiral perturbation theory. The result is shown to be dominated by resonance-region contributions encoded in a single low-energy constant whose value is known from flavor-breaking hadronic $\tau$ decay sum rules. Implications of the form of the result for lattice determinations of $a_\mu^{SIB}$ are also discussed.

• Probing new physics with the leptonic g-2

  Paride Paradisi

  SciPost Phys. Proc. 16, 030 (2025) · published 15 July 2025 | Toggle abstract · pdf

  We present a concise review of the new physics sensitivity of leptonic dipole moments and their interrelationship. In particular, focusing on the current muon g-2 anomaly, we analyse both high-energy and low-energy tests to confirm or to falsify it.