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تسجيل مستخدم جديدAlgebraic model for single-particle energies of $Lambda$ hypernuclei
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A model is proposed for the spectrum of $Lambda$ hypernuclei based on the $u(3)times u(2)$ Lie algebra, in which the internal degrees of freedom of the spin-1/2 $Lambda$ particle are treated in the Fermionic $u(2)$ scheme, while the motion of the hyperon inside a nucleus is described in the Bosonic $u(3)$ harmonic oscillator scheme. Within this model, a simple formula for single-particle energies of the $Lambda$ particle is obtained from the natural dynamical symmetry. The formula is applied to the experimental data on the reaction spectroscopy for the $^{89}_Lambda$Y and $^{51}_Lambda$V hypernuclei, providing a clear theoretical interpretation of the observed structures.
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Having in mind its future extension for theoretical investigations related to charmed nuclei, we develop a relativistic formalism for the nonmesonic weak decay of single-$Lambda$ hypernuclei in the framework of the independent-particle shell model an
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We extend the relativistic point coupling model to single-$Lambda$ hypernuclei. For this purpose, we add $N$-$Lambda$ effective contact couplings to the model Lagrangian, and determine the parameters by fitting to the experimental data for $Lambda$ b
inding energies. Our model well reproduces the data over a wide range of mass region although some of our interactions yield the reverse ordering of the spin-orbit partners from that of nucleons for heavy hypernuclei. The consistency of the interaction with the quark model predictions is also discussed.
A particle-hole model is developed to describe the excitation spectrum of single lambda hypernuclei and the possible presence of collective effects is explored by making a comparison with the mean-field calculations. Results for the spectra of 12C, 1
6O, 40Ca, 90Zr and 208Pb single lambda hypernuclei are shown. The comparison with the available experimental data is satisfactory. We find that collective phenomena are much less important in hypernuclei than in ordinary nuclei.
$Lambda^+_c$- and $Lambda_b$-hypernuclei are studied in the quark-meson coupling (QMC) model. Comparisons are made with the results for $Lambda$-hypernuclei studied in the same model previously. Although the scalar and vector potentials felt by the $
Lambda$, $Lambda_c^+$ and $Lambda_b$ in the corresponding hypernuclei multiplet which has the same baryon numbers are quite similar, the wave functions obtained, e.g., for $1s_{1/2}$ state, are very different. The $Lambda^+_c$ baryon density distribution in $^{209}_{Lambda^+_c}$Pb is much more pushed away from the center than that for the $Lambda$ in $^{209}_Lambda$Pb due to the Coulomb force. On the contrary, the $Lambda_b$ baryon density distributions in $Lambda_b$-hypernuclei are much larger near the origin than those for the $Lambda$ in the corresponding $Lambda$-hypernuclei due to its heavy mass. It is also found that level spacing for the $Lambda_b$ single-particle energies is much smaller than that for the $Lambda$ and $Lambda^+_c$.
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