New behaviors of α-particle preformation factors near doubly magic 100Sn

The α-particle preformation factors of nuclei above doubly magic nuclei 100Sn and 208Pb are investigated.The results show that the α-particle preformation factors of nuclei near self-conjugatedoubly magic 100Sn are larger significantly than those of analogous nuclei just above 208Pb, andthey will be enhanced as the nuclei move towards the N = Z line. The correlation energy of theproton-neutron Ep-n and two protons-two neutrons E2p-2n of nuclei near 100Sn also exhibit similarsituations indicating that the interactions between protons and neutrons occupying similar single-particleorbitals could enhance the α-particle preformation factors and result in the superallowedα decay. It also provides evidence of the significant role of proton-neutron interaction on α-particlepreformation. Besides, the linear relationship between α-particle preformation factors and the productof valence protons and valence neutrons for nuclei around 208Pb is broken in the 100Sn regionbecause the α-particle preformation factor is enhanced when the nucleus near 100Sn moves towardsthe N = Z line. Furthermore, the calculated decay half-lives can well reproduce the experimentaldata including the recent observed self-conjugate nuclei 104Te and 108Xe [Phys. Rev. Lett. 121,182501 (2018)].

Constraints on the $$\varLambda $$-Neutron Interaction from Charge Symmetry Breaking in the $$\mathbf {^4_\Lambda \mathrm{He}}$$ - $$\mathbf {^4_\Lambda \mathrm{H}}$$ Hypernuclei

We utilize the experimentally known difference of the $$\varLambda $$ Λ separation energies of the mirror hypernuclei $${^4_\varLambda \mathrm{He}}$$ Λ 4 He and $${^4_\varLambda \mathrm{H}}$$ Λ 4 H to constrain the $$\varLambda $$ Λ -neutron interaction. We include the leading charge-symmetry breaking (CSB) interaction into our hyperon-nucleon interaction derived within chiral effective field theory at next-to-leading order. In particular, we determine the strength of the two arising CSB contact terms by a fit to the differences of the separation energies of these hypernuclei in the $$0^+$$ 0 + and $$1^+$$ 1 + states, respectively. By construction, the resulting interaction describes all low energy hyperon-nucleon scattering data, the hypertriton and the CSB in $${^4_\varLambda \mathrm{He}}$$ Λ 4 He -$${^4_\varLambda \mathrm{H}}$$ Λ 4 H accurately. This allows us to provide first predictions for the $$\varLambda $$ Λ n scattering lengths, based solely on available hypernuclear data.

Nilsson orbitals in quantum superintegrable systems

Recent studies [1] of the valence proton-neutron interaction through certain double differences of binding energies suggest that Nilsson orbitals with ΔK[ΔNΔn_zΔΛ] = 0[110] are responsible for large overlaps of wave functions in heavy deformed nuclei. We show that pairs of orbitals of this kind belong to neighboring irreducible representations of appropriate deformed U(3) algebras [2], being interconnected by deformed creation and annihilation operators. These deformed U(3) algebras correspond to oscillators with rational ratios of frequencies, which are examples of quantum superintegrable systems [3].