Chiral dynamics of {sigma} hyperons in the nuclear medium

Journal Article · Wed Jun 01 04:00:00 EDT 2005 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.71.068201· OSTI ID:20698793

Kaiser, N ^[1]

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1. Physik-Department T39, Technische Universitaet Muenchen, D-85747 Garching (Germany)

Using SU(3) chiral perturbation theory, we calculate the density-dependent complex mean field U{sub {sigma}}(k{sub f})+i W{sub {sigma}}(k{sub f}) of a {sigma} hyperon in isospin-symmetric nuclear matter. The leading long-range {sigma}N interaction arises from one-kaon exchange and from two-pion exchange with a {sigma} or a {lambda} hyperon in the intermediate state. We find from the {sigma}N{yields}{lambda}N conversion process at nuclear matter saturation density {rho}{sub 0}=0.16 fm{sup -3} an imaginary single-particle potential of W{sub {sigma}}(k{sub f0})=-21.5 MeV, in fair agreement with existing empirical determinations. The genuine long-range contributions from iterated (second order) one-pion exchange with an intermediate {sigma} or {lambda} hyperon sum to a moderately repulsive real single-particle potential of U{sub {sigma}}(k{sub f0})=59 MeV. Recently measured ({pi}{sup -},K{sup +}) inclusive spectra related to {sigma}{sup -} formation in heavy nuclei give evidence for a {sigma}-nucleus repulsion of similar size. Our results suggest that the net effect of the short-range {sigma}N interaction on the {sigma} nuclear mean field could be small.

• OSTI ID: 20698793
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 6 Vol. 71; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CHIRAL SYMMETRY
CHIRALITY
HEAVY NUCLEI
HYPERNUCLEI
INTERMEDIATE STATE
ISOSPIN
KAONS PLUS
MEAN-FIELD THEORY
MEV RANGE
NUCLEAR MATTER
NUCLEAR POTENTIAL
NUCLEON-HYPERON INTERACTIONS
PERTURBATION THEORY
PION-NUCLEON INTERACTIONS
PIONS MINUS
QUANTUM FIELD THEORY
SIGMA MINUS PARTICLES
SU-3 GROUPS