Strange quark mass from Finite Energy QCD sum rules to five loops

TL;DR

This paper determines the strange quark mass using an improved QCD Finite Energy Sum Rule approach with five-loop perturbative calculations, reducing systematic uncertainties and achieving stable results across a wide energy range.

Contribution

It introduces a new FESR optimized to minimize resonance sector uncertainties and employs five-loop perturbative QCD with CIPT for a precise strange quark mass determination.

Findings

Strange quark mass at 2 GeV is approximately 95 MeV for Λ_QCD=420 MeV.

The method achieves stable results across a wide energy range.

CIPT shows very good convergence in this analysis.

Abstract

The strange quark mass is determined from a new QCD Finite Energy Sum Rule (FESR) optimized to reduce considerably the systematic uncertainties arising from the hadronic resonance sector. As a result, the main uncertainty in this determination is due to the value of $\Lambda_{QCD}$. The correlator of axial-vector divergences is used in perturbative QCD to five-loop order, including quark and gluon condensate contributions, in the framework of both Fixed Order (FOPT), and Contour Improved Perturbation Theory (CIPT). The latter exhibits very good convergence, leading to a remarkably stable result in the very wide range $s_0 = 1.0 - 4.0 {GeV}^2$, where $s_0$ is the radius of the integration contour in the complex energy (squared) plane. The value of the strange quark mass in this framework at a scale of 2 GeV is $m_s(2 {GeV}) = 95 \pm 5 (111 \pm 6) {MeV}$ for $\Lambda_{QCD} = 420 (330) {MeV}$, respectively.