Shell model formalism for all hypernuclei types: A guide to solving the nonmesonic weak decay puzzle

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

DOI:https://doi.org/10.1103/PHYSREVC.78.044324· OSTI ID:21192303

Barbero, C; Mariano, A; Samana, A ^[1]

---

1. Departamento de Fisica, Universidad Nacional de La Plata, C. C. 67, 1900 La Plata (Argentina) and Instituto de Fisica CCT La Plata, CONICET, 1900 La Plata (Argentina)

We extend to odd-odd core hypernuclei our independent particle shell model (IPSM) formalism developed previously for the evaluation of the {gamma}{sub NM},{gamma}{sub n/p}, and a{sub {lambda}} hypernuclear weak decay observables. The present procedure reproduces the even-odd and even-even core results as particular cases. Adopting the standard strangeness-changing weak {lambda}N{yields}NN transition potential with exchange of the complete pseudoscalar and vector meson octets ({pi},{eta},K,{rho},{omega},K*) we get simple analytical expressions for all observables. Numerical values for {sub {lambda}}{sup 4}He,{sub {lambda}}{sup 5}He, {sub {lambda}}{sup 11}B,{sub {lambda}}{sup 12}C,{sub {lambda}}{sup 16}O, {sub {lambda}}{sup 17}O, and {sub {lambda}}{sup 28}Si hypernuclei are obtained and compared with available experimental data, putting special attention on the asymmetry parameter. We remark that, in the present form, the IPSM gives roughly the same value of a{sub {lambda}} for all hypernuclei in contradiction with experiments. We stress the necessity of introducing configuration mixing to go beyond the IPSM taking into account, in a more realistic way, nuclear structure effects. Moreover, one could to include more relevant degrees of freedom, even within the IPSM framework, like: (i) modifications of the exchange potential (two-pion, a{sub 1} meson, {delta}T=3/2 terms of vector mesons, etc.), (ii) final state interactions accounting for the distortion of the plane waves of emitted nucleons, and (iii) two-nucleon induced decay, as possible ways to solve the puzzle.

• OSTI ID: 21192303
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 4 Vol. 78; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASYMMETRY
BORON 11
CARBON 12
CONFIGURATION MIXING
DECAY
DEGREES OF FREEDOM
EMISSION
FINAL-STATE INTERACTIONS
HELIUM 4
HELIUM 5
HYPERNUCLEI
LAMBDA PARTICLES
MODIFICATIONS
NUCLEAR STRUCTURE
NUCLEON-NUCLEON INTERACTIONS
NUCLEONS
ODD-ODD NUCLEI
OMEGA PARTICLES
OXYGEN 16
OXYGEN 17
PIONS
SHELL MODELS
SILICON 28
STRANGENESS
STRESSES
VECTOR MESONS
WAVE PROPAGATION