Pion propagator in relativistic quantum field theories of the nuclear many-body problem

Journal Article · Mon Nov 01 00:00:00 EST 1982 · Ann. Phys. (N.Y.); (United States)

DOI:https://doi.org/10.1016/0003-4916(82)90106-3· OSTI ID:5982122

Matsui, T; Serot, B D

Pion interactions in the nuclear medium are studied using renormalizable relativistic quantum field theories. Previous studies using pseudoscalar ..pi..N coupling encountered difficulties due to the large strength of the ..pi..NN vertex. We therefore formulate renormalizable field theories with pseudovector ..pi..N coupling using techniques introduced by Weinberg and Schwinger. Calculations are performed for two specific models; the scalar-vector theory of Walecka, extended to include ..pi.. and rho mesons in a non-chiral fashion, and the linear sigma-model with an additional neutral vector meson. Both models qualitatively reproduce low-energy ..pi..N phenomenology and lead to nuclear matter saturation in the relativistic Hartree formalism, which includes baryon vacuum fluctuations. The pions propagator is evaluated in the one-nucleon-loop approximation, which corresponds to a relativistic random-phase approximation built on the Hartree ground state. Virtual NN-bar loops are included, and suitable renormalization techniques are illustrated. The local-density approximation is used to compare the threshold pion self-energy to the s-wave pion-nucleus optical potential. In the non-chiral model, s-wave pion-nucleus scattering is too large in both pseudoscalar and pseudovector calculations, indicating that additional constraints must be imposed on the Lagrangian. In the chiral model, the threshold self-energy vanishes automatically in the pseudovector case, but does so for pseudoscalar coupling only if the baryon effective mass is chosen self-consistently Since extrapolation from free space to nuclear density can lead to large effects, pion propagation in the medium can determine which ..pi..N coupling is more suitable for the relativistic nuclear many-body problem. Conversely, pion interactions constrain the model Lagrangian and the nuclear matter equation of state. An approximately chiral model with pseudovector coupling is favored.

• Research Organization: Institute of Theoretical Physics, Department of Physics, Stanford University, Stanford, California 94305
• OSTI ID: 5982122
• Journal Information: Ann. Phys. (N.Y.); (United States), Vol. 144:1
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
NUCLEAR MATTER
PION-NUCLEON INTERACTIONS
PIONS
PROPAGATOR
CHIRALITY
COUPLING CONSTANTS
LAGRANGIAN FUNCTION
MANY-BODY PROBLEM
NUCLEAR STRUCTURE
QUANTUM FIELD THEORY
RENORMALIZATION
SCATTERING AMPLITUDES
SELF-ENERGY
AMPLITUDES
BOSONS
ELEMENTARY PARTICLES
ENERGY
FIELD THEORIES
FUNCTIONS
HADRON-HADRON INTERACTIONS
HADRONS
INTERACTIONS
MATTER
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
MESONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PSEUDOSCALAR MESONS
653002* - Nuclear Theory- Nuclear Matter
645400 - High Energy Physics- Field Theory