Estimates of the pion-nucleon sigma term using dispersion relations and taking into account the relation between chiral and scale invariance breaking

Journal Article · Tue Mar 01 04:00:00 EST 1983 · Sov. J. Nucl. Phys. (Engl. Transl.); (United States)

OSTI ID:5703675

Efrosinin, V P; Zaikin, D A

We study the possible reasons for the disagreement between the estimates of the pion-nucleon sigma term obtained by the method of dispersion relations with extrapolation to the Cheng-Dashen point and by other methods which do not involve this extrapolation. One reason for the disagreement may be the nonanalyticity of the ..pi..N amplitude in the variable t for ..nu.. = 0. We propose a method for estimating the sigma term using the threshold data for the ..pi..N amplitude, in which the effect of this nonanalyticity is minimized. We discuss the relation between scale invariance violation and chiral symmetry breaking and give the corresponding estimate of the sigma term. The two estimates are similar (42 and 34 MeV) and are in agreement when the uncertainties of the two methods are taken into consideration.

• Research Organization: Institute of Nuclear Research, USSR Academy of Sciences
• OSTI ID: 5703675
• Journal Information: Sov. J. Nucl. Phys. (Engl. Transl.); (United States), Journal Name: Sov. J. Nucl. Phys. (Engl. Transl.); (United States) Vol. 37:3; ISSN SJNCA
• Country of Publication: United States
• Language: English

Related Subjects

645303* -- High Energy Physics-- Particle Invariance Principles & Symmetries-- Applications to Strong Interactions-- (-1987)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
CHIRAL SYMMETRY
DISPERSION RELATIONS
HADRON-HADRON INTERACTIONS
INTERACTIONS
ISOSPIN
LIE GROUPS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PION-NUCLEON INTERACTIONS
SCALING LAWS
SCATTERING AMPLITUDES
SU GROUPS
SU-2 GROUPS
SYMMETRY
SYMMETRY BREAKING
SYMMETRY GROUPS