arXiv subjects

Lucas M. Mansur

Publications and source records attributed to Lucas M. Mansur.

2 recordsLinked to original sources

arXiv2026

Comparison of the hadronic vacuum polarization between hadronic $τ$-decay data and lattice QCD

We compare the isospin-one, vector-current hadronic vacuum polarization (HVP) obtained from isospin-symmetric lattice QCD with that obtained from a dispersive representation employing inclusive hadronic $τ$ decay data corrected for isospin breaking. We consider the subtracted HVP evaluated at squared Euclidean momenta ranging from $0.5$ GeV$^2$ to $12$ GeV$^2$, together with the light-quark-connected HVP contribution to the muon anomalous magnetic moment and the short-, intermediate- and long-distance RBC/UKQCD window components thereof. Dispersive contributions from the region of hadronic invariant masses above the $τ$ mass are evaluated using perturbative QCD. We also consider dispersive determinations using $τ$ data only for contributions from two-pion, or two-pion and four-pion, modes, and evaluating the remaining contributions using exclusive-mode $e^+e^-\to\mbox{hadrons}$ cross sections up to about 2 GeV, lessening the dependence on perturbation theory. We find generally good agreement between lattice and $τ$-based results. However, a comparison of $τ$-based window-quantity contributions for the two four-pion modes to expectations for those contributions based on the Pais relations and $e^+e^-$ four-pion cross sections, reveals significant differences for the $2π^-π^+π^0$ mode.

hep-ph↗

arXiv2025

The strong coupling from hadronic $τ$-decay data including $τ\toπ^-π^0ν_τ$ from Belle

In previous work we have combined the $π^-π^0$, $2π^-π^+π^0$ and $π^-3π^0$ spectral data obtained from hadronic $τ$ decays measured by the ALEPH and OPAL experiments, together with electroproduction data for several of the subleading hadronic modes and BaBar data for the $K\bar{K}$ mode to construct an inclusive non-strange vector spectral function entirely based on experimental data, with no Monte-Carlo generated input. In this paper, we include, for the first time, the Belle $τ\toπ^-π^0ν_τ$ high-statistics decay data to construct a new inclusive non-strange vector spectral function that combines more of the world's available data. As no Belle data are at present available for the two $4π$ modes, this requires a revised data analysis in comparison with our previous work. From the resulting new spectral function, we obtain a new determination of the strong coupling, $α_s$, using our previously developed strategy based on finite-energy sum rules. We find, at the $Z$ mass scale, $α_s(m_Z^2)=0.1159(14)$. We discuss the smaller central value and larger error of our new result compared to our previous result, showing the shifts to be due mainly to significant changes in updated HFLAV results for the $π^-3π^0$ decay mode.

hep-ph↗