Core nucleus polarization in {lambda} hypernuclei

Journal Article · Sat Mar 15 04:00:00 EDT 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.77.034312· OSTI ID:21189830

Usmani, Q N ^[1]; Bodmer, A R ^[2]; Sauli, Z ^[3]

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1. Institute of Engineering Mathematics, University Malaysia Perlis (Malaysia)
2. Department of Physics, University of Illinois at Chicago, Chicago, Illinois (United States)
3. School of Microelectronics Engineering, University Malaysia Perlis (Malaysia)

The response of the core nucleus to the {lambda} in a hypernucleus is studied with a local density approximation. This reproduces the energies and radii of the core nuclei as well as the {lambda}-single particle (s.p.) energies quite well. The polarizing effect of the {lambda} depends on the core response through an 'effective' compression modulus K{sub A} of the nucleus. For a certain class of energy functional, K{sub A} is found to be almost independent of the compression modulus K of the infinite nuclear matter. This indeed is a surprising result, and varies with the Hartree-Fock calculations with effective interactions. Reasons for this discrepancy are carefully examined. We consider values of K in the range {approx_equal}100-400 MeV. Furthermore, the polarizing effects also depend critically on D({rho}), the {lambda} binding in nuclear matter at density {rho}. For only a direct {lambda}N force: D{proportional_to}{rho} and the core nucleus contracts giving rise to relatively larger core polarization. However, for a ''saturating'' D({rho}) (with a maximum at {rho}{sub m}<{rho}{sub 0}, where {rho}{sub 0} is the nuclear matter equilibrium density), which is required to fit the s.p. data, the s-shell hypernuclei binding energies and the low energy {lambda}p scattering data, which results from a {lambda}N force (including exchange) and {lambda}NN forces, there may be an expansion of the nucleus with nucleons flowing from the interior to the surface. This is shown to reduce the core polarization effects substantially (for {rho}{sub m} in the neighborhood of {rho}{sub 0}). The resulting changes in root mean square radius and core energy depend on A, but are mostly very small, justifying their general neglect.

• OSTI ID: 21189830
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 77; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BINDING ENERGY
COMPRESSION
DENSITY
EQUILIBRIUM
EXPANSION
HARTREE-FOCK METHOD
HYPERNUCLEI
INTERACTIONS
MEV RANGE
NUCLEAR MATTER
NUCLEON-NUCLEON INTERACTIONS
NUCLEONS
PARTICLES
POLARIZATION
SCATTERING
SURFACES