Smeared $R$-ratio in isospin symmetric QCD with Low Mode Averaging

TL;DR

This paper demonstrates how Low Mode Averaging enhances the calculation of smeared R-ratios in isospin symmetric QCD, revealing the rho resonance using spectral density reconstruction in lattice simulations.

Contribution

It introduces the application of Low Mode Averaging to improve the computation of smeared R-ratios and spectral densities in isospin symmetric QCD lattice studies.

Findings

Improved signal quality in vector-vector correlators.

Successful extraction of the rho resonance around 770 MeV.

Preliminary results showing the effectiveness of LMA in spectral density analysis.

Abstract

Low Mode Average (LMA) is a technique to improve the quality of the signal-to-noise ratio in the long time separation of Euclidean correlation functions. We report on its beneficial impact in computing the vector-vector light connected two-point correlation functions and derived physical quantities in the mixed action lattice setup adopted by ETM collaboration. We focus on preliminary results of the computation within isospin symmetric QCD (isoQCD) of the $R$-ratio smeared with Gaussian kernels of widths down to $\sigma\sim250$ MeV, which is enough to appreciate the $\rho$ resonance around 770 MeV, using the Hansen-Lupo-Tantatlo (HLT) spectral-density reconstruction method.