Extracting the Omega- electric quadrupole moment from lattice QCD data

TL;DR

This paper estimates the electric quadrupole moment of the Omega- baryon using a covariant spectator quark model calibrated to lattice QCD data, providing the first such prediction based on this approach.

Contribution

The work introduces a novel method combining lattice QCD data with a covariant quark model to estimate the Omega- electric quadrupole moment.

Findings

Predicted Q_Omega= (0.96 +/- 0.02) x 10^(-2) efm^2

GE2(0)=0.680 +/- 0.012

Model accurately reproduces lattice QCD form factors

Abstract

The Omega- has an extremely long lifetime, and is the most stable of the baryons with spin 3/2. Therefore the Omega- magnetic moment is very accurately known. Nevertheless, its electric quadrupole moment was never measured, although estimates exist in different formalisms. In principle, lattice QCD simulations provide at present the most appropriate way to estimate the Omega- form factors, as function of the square of the transferred four-momentum, Q2, since it describes baryon systems at the physical mass for the strange quark. However, lattice QCD form factors, and in particular GE2, are determined at finite Q2 only, and the extraction of the electric quadrupole moment, Q_Omega= GE2(0) e/(2 M_Omega), involves an extrapolation of the numerical lattice results. In this work we reproduce the lattice QCD data with a covariant spectator quark model for Omega- which includes a mixture of S and two D states for the relative quark-diquark motion. Once the model is calibrated, it is used to determine Q_Omega. Our prediction is Q_Omega= (0.96 +/- 0.02)*10^(-2) efm2 [GE2(0)=0.680 +/- 0.012].