Scalar-isoscalar states in the large-Nc Regge approach

TL;DR

This paper investigates scalar-isoscalar states within the large-Nc Regge framework, incorporating the lightest f0(600) state, and uses lattice data and QCD condensates to analyze their spectrum and nature.

Contribution

It introduces a comprehensive analysis of scalar-isoscalar states using the Regge approach, including the f0(600) and f0(980), and connects lattice data and QCD condensates to their properties.

Findings

f0(600) fits well into the Regge trajectory

m_sigma estimated as 450-600 MeV

f0(600) likely meson, f0(980) likely glueball

Abstract

Scalar-isoscalar states (0++) are investigated within the large-Nc Regge approach. We elaborate on the consequences of including the lightest f0(600) scalar-isoscalar state into such an analysis, where the position of f0(600) fits very well into the pattern of the radial Regge trajectory. Furthermore, we point out that the pion and nucleon spin-0 gravitational form factors, recently measured on the lattice, provide valuable information on the low-mass spectrum of the scalar-isoscalar states on the basis of the scalar-meson dominance in the spin-0 channel. Through the fits to these data we find m_sigma= 450-600 MeV. We compare the predictions of various fits and methods. An analysis of the QCD condensates in the two-point correlators provides further constraints on the parameters of the scalar-isoscalar sector. We find that a simple two-state model suggests a meson nature of f0(600), and a glueball nature of f0(980), which naturally explains the ratios of various coupling constants. Finally, we note that the fine-tuned condition of the vanishing dimension-2 condensate in the Regge approach with infinitely many scalar-isoscalar states yields a reasonable value for the mass of the lighest glueball state.