Explicit chiral symmetry breaking in the Nambu-Jona-Lasinio model
Nov, 1991
21 pages
Published in:
- Nucl.Phys.A 547 (1992) 612-632
- Published: 1992
Report number:
- RUB-TPII-07-91
Citations per year
Abstract: (Elsevier)
We consider a chirally symmetric bosonization of the SU(2) Nambu-Jona-Lasinio model within the Pauli-Villars regularization scheme. Special attention is paid to the way in which chiral symmetry is broken explicitly. The parameters of the model are fixed in the light of chiral perturbation theory by performing a covariant derivative expansion in the presence of external fields. As a by-product we obtain the corresponding low-energy parameters and pion radii as well as some threshold parameters for pion-pion scattering. The nucleon is obtained in terms of the solitonic solutions of the action in the sector with baryon number equal to one. It is found that for a constituent quark mass M ∼ 350 MeV most of the calculated vacuum and pion properties agree reasonably well with the experimental ones and coincide with the region where localized solitons with the right size exist. For this value, however, the scalar and vector pion radii turn out to be very small. A unique determination of the sigma term is proposed, obtaining a value of σ (0) = 41.3 MeV. The scalar nucleon form factor is evaluated in the Breit frame. The extrapolation to the Cheng-Dashen point leads to σ (2 m 2 ) − σ (0) = 7.4 MeV.- Jona-Lasinio-Nambu model: SU(2)
- symmetry breaking: chiral
- bosonization
- regularization: Pauli-Villars
- perturbation theory: chiral
- pi pi: interaction
- interaction: pi pi
- pi nucleon: sigma term
- nucleon: form factor
- form factor: nucleon
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