Comparing phenomenological estimates of dilepton decays of pseudoscalar mesons with lattice QCD

TL;DR

This paper compares phenomenological estimates and lattice QCD calculations of dilepton decays of pseudoscalar mesons, highlighting recent advances, uncertainties, and implications for Standard Model predictions and beyond.

Contribution

It presents a comparative analysis of phenomenological models and lattice QCD results for pseudoscalar meson dilepton decays, including recent predictions for $ ext{π}^0 o e^+e^-$ and $K_L o ext{l}^+ ext{l}^-$ decays.

Findings

Lattice QCD provides first-principles predictions consistent with phenomenological estimates.

Uncertainty estimates can be improved with future experiments and lattice advancements.

The study enhances understanding of low-energy QCD dynamics and rare decay processes.

Abstract

Dilepton decays of pseudoscalar mesons have been drawing particular interest, thanks to their sensitivity to both the QCD dynamics at low energy and also signals beyond the Standard Model. In this context, we shortly review our recent study on an improved Standard-Model prediction for the rare decay $\pi^0\to e^+e^-$, and compare it with the first determination on the lattice that predicted also the $\pi^0\to \gamma\gamma $ decay width as a byproduct. In addition, we discuss our recent work on $K_L\to\ell^+\ell^-$ decays and its connection to lattice QCD. We comment on the current uncertainty estimates and discuss how they could be improved profiting from future experiments and progress in lattice QCD.