Chiral perturbation theory with nucleons

Technical Report · Sun Sep 01 00:00:00 EDT 1991

DOI:https://doi.org/10.2172/6095581· OSTI ID:6095581

Meissner, U G

I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, {pi}N scattering and the {sigma}-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.

• Research Organization: Bern Univ. (Switzerland). Inst. fuer Theoretische Physik; Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG06-90ER40561
• OSTI ID: 6095581
• Report Number(s): DOE/ER/40561-28; ON: DE92004383
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CHIRAL SYMMETRY
SYMMETRY BREAKING
MESONS
NUCLEONS
COMPTON EFFECT
FORM FACTORS
GREEN FUNCTION
HAMILTONIANS
LAGRANGIAN FUNCTION
MAGNETIC MOMENTS
PERTURBATION THEORY
PION-NUCLEON INTERACTIONS
QUANTUM CHROMODYNAMICS
SCATTERING AMPLITUDES
AMPLITUDES
BARYONS
BASIC INTERACTIONS
BOSONS
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
FERMIONS
FIELD THEORIES
FUNCTIONS
HADRON-HADRON INTERACTIONS
HADRONS
INTERACTIONS
MATHEMATICAL OPERATORS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
QUANTUM FIELD THEORY
QUANTUM OPERATORS
SCATTERING
SYMMETRY
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