Speaker
Description
The R-ratio is a phenomenologically important observable, relevant both in its own right and in applications such as the dispersive approach to the muon anomalous magnetic moment. A first-principles lattice QCD investigation of the R-ratio can be carried out with controlled statistical and systematic uncertainties, by introducing a suitable energy-smearing kernel and employing spectral reconstruction techniques, such as the Hansen-Lupo-Tantalo algorithm. Building on our first study published in 2023, we present preliminary results using the correlation functions produced by ETMC in Nf=2+1+1 lattice simulations at four lattice spacings, different volumes and with higher statistics than in our previous work. The new correlators, thanks to the implementation of the Low Mode Averaging technique, allow the determination of the R-ratio smeared with Gaussian kernels of widths down to σ∼200 MeV with phenomenologically relevant precision.