Nature of the sigma meson as revealed by its softening process

Abstract

The pi pi scattering is studied in two-flavor chiral models with a finite pion mass to investigate the nature of the sigma meson which is observed as the lowest scalar-isoscalar resonance. We compare several models with different origins of the sigma meson, such as the chiral partner of the pion and the dynamically generated pi pi molecule. We find that the dynamically generated sigma meson exhibits a novel pattern of the threshold enhancement reflecting the s-wave nature of the resonance, which is qualitatively different from the softening of the chiral partner introduced as a bare field. This behavior around the threshold energy region is universal as far as the bare sigma pole stays away from the threshold throughout the symmetry restoration process. On the other hand, for m_pi=0, the dynamically generated sigma behaves similarly to the chiral partner in the symmetry restoration limit, implying the possibility of the dynamically generated chiral partner.

arXiv comment33 pages, 7 figures, 4 tables, version accepted in Nucl. Phys. A

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Cited by in corpus (20)

• From controversy to precision on the sigma meson: a review on the status of the non-ordinary $f_0(500)$ resonance
• The nature of the Lambda(1405) resonance in chiral dynamics
• Compositeness of dynamically generated states in a chiral unitary approach
• Comprehensive analysis of the wave function of a hadronic resonance and its compositeness
• Structure and compositeness of hadron resonances
• Exotic baryons from a heavy meson and a nucleon -- Negative parity states --
• Identification of non-ordinary mesons from the dispersive connection between their poles and their Regge trajectories: the f0(500) resonance
• Chiral condensate at finite density using chiral Ward identity
• Theoretical support for the $\pi (1300)$ and the recently claimed $f_0(1790)$ as molecular resonances
• Elementarity of composite systems
• Enhanced non-quark-antiquark and non-glueball Nc behavior of light scalar mesons
• Preliminary lattice study of $\sigma$ meson decay width
• Dispersive calculation of complex Regge trajectories for the lightest $f_2$ resonances
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• Composite and elementary nature of a resonance in the sigma model
• Role of U${}_A$(1) breaking term in dynamical chiral symmetry breaking of chiral effective theories
• Nature of the D_0 meson in the D pi scattering with chiral symmetry
• The $\eta$ decay into 3$\pi$ in asymmetric nuclear medium
• Structure of the sigma meson and the softening