19B isotope as a 17B-n-n three-body cluster close to unitary limit

Shape coexistence close to $N=50$ in the neutron-rich isotope $^{80}$Ge investigated by IBM-2

The properties of the low-lying states, especially the relevant shape coexistence in $^{80}$Ge close to one of most neutron-rich doubly magic nuclei at $N=50$ and $Z=28$ have been investigated within the framework of the proton-neutron interacting model (IBM-2). Based on the fact that the relative energy of the $d$ neutron boson is different from proton bosons', the calculated energy levels of low-lying states, $E2$ transition strengths can reproduce the experimental data very well. Particularly, the first excited state 0$^+_2$ is reproduced quite nicely, which is intimately related with the s…

Stability of 248-254^Cf isotopes against alpha and cluster radioactivity

Stability of 248-254^Cf nuclei against alpha and cluster emission is studied within our Coulomb and proximity potential model (CPPM). It is found that these nuclei are stable against light clusters (except alpha particle) and instable against heavy cluster emissions. For heavy cluster emissions the daughter nuclei lead to doubly magic 208^Pb or neighbouring one. The effect of quadrapole and hexadecapole deformations of parent nuclei, daughter nuclei and emitted cluster on half lives are also studied. The computed alpha decay half life values (with including quadrupole deformation β2) are in cl…

Neutrinos and rare isotopes

The close connection between neutrino physics and the physics explored at rare isotope facilities is explored. The duality between the Hamiltonian describing the self-interacting neutrino gas near the proto-neutron star in a core-collapse supernova and the BCS theory of pairing is elucidated. This many neutrino system is unique as it is the only many-body system driven by weak interactions. Its symmetries are discussed.

Evolution of the proton sd states in neutron-rich Ca isotopes

We analyze the evolution with increasing isospin asymmetry of the proton single-particle states 2s1/2 and 1d3/2 in Ca isotopes, using non-relativistic and relativistic mean field approaches. Both models give similar trends and it is shown that this evolution is sensitive to the neutron shell structure, the two states becoming more or less close depending on the neutron orbitals which are filled. In the regions where the states get closer some parametrizations predict an inversion between them. This inversion occurs near $^{48}$Ca as well as very far from stability where the two states systemat…

Particle-particle random phase approximation applied to Beryllium isotopes

This work is dedicated to the study of even-even 8-14 Be isotopes using the particle-particle Random Phase Approximation that accounts for two-body correlations in the core nucleus. A better description of energies and two-particle amplitudes is obtained in comparison with models assuming a neutron closed-shell (or subshell) core. A Wood-Saxon potential corrected by a phenomenological particle-vibration coupling term has been used for the neutron-core interaction and the D1S Gogny force for the neutron-neutron interaction. Calculated ground state properties as well as excited state ones are di…

Onset of $η$-meson binding in the He isotopes

The onset of binding $η$(548) mesons in nuclei is studied in the He isotopes by doing precise $ηNNN$ and $ηNNNN$ few-body stochastic variational method calculations for two semi-realistic $NN$ potentials and two energy dependent $ηN$ potentials derived from coupled-channel models of the $N^{\ast}(1535)$ nucleon resonance. The energy dependence of the $ηN$ subthreshold input is treated self consistently. It is found that a minimal value of the real part of the $ηN$ scattering length $a_{ηN}$ close to 1 fm is required to bind $η$ mesons in $^3$He, yielding then a few MeV $η$ binding in $^4$He. T…

Density functional theory for fermions close to the unitary regime

We consider interacting Fermi systems close to the unitary regime and compute the corrections to the energy density that are due to a large scattering length and a small effective range. Our approach exploits the universality of the density functional and determines the corrections from the analyical results for the harmonically trapped two-body system. The corrections due to the finite scattering length compare well with the result of Monte Carlo simulations. We also apply our results to symmetric neutron matter.

铟同位素的电磁性质阐明$^{100}$Sn的双幻核特性

Electromagnetic Properties of Indium Isotopes Elucidate the Doubly Magic Character of $^{100}$Sn

针对$^{100}$Sn双幻核特性的长期研究挑战，本研究通过精密激光光谱学测量铟同位素的电磁矩与核电荷半径，发现其随中子数的抛物线趋势支持$^{100}$Sn的双幻性，并为核模型缺陷及未来理论发展提供基准。

富中子P、Cl和K同位素的从头算价空间介质内相似重整化群计算

Ab initio valence-space in-medium similarity renormalization group calculations for neutron-rich P, Cl, and K isotopes

本文利用从头算价空间介质内相似重整化群方法研究富中子P、Cl、K同位素，发现奇A核中3/2₁⁺与1/2₁⁺态能级反转源于π0d₃/₂和π1s₁/₂单粒子态反转，并揭示三体力对Z=14和16亚壳层壳演化的重要作用。

Spin 1/2 Fermions in the Unitary Limit.II

This report concerns the energy of a zero-temperature many-body system of spin 1/2 fermions in the unitary limit. In a previous report (arXiv:0705.0944) this energy was determined to be xi~0.24 in units of the free gas kinetic energy, appreciably lower than most reports giving ~0.45$. In our calculation the 2-body interaction satisfied exactly the unitary limit i.e. infinite scattering length and effective range r_0=0. In the present report results with r_0>0are shown. A strong dependence on the effective range is found. It is for example found that an increase to r_0=1 fm increases xi to ~ 0.…

Quantitative study of coherent pairing modes with two neutron transfer: Sn-isotopes

Pairing rotations and pairing vibrations are collective modes associated with a field, the pair field, which changes the number of particles by two. Consequently, they can be studied at profit with the help of two-particle transfer reactions on superfluid and in normal nuclei, respectively. The advent of exotic beams has opened, for the first time, the possibility to carry out such studies in medium heavy nuclei, within the same isotopic chain. In the case studied in the present paper that of the Sn-isotopes (essentially from closed (Z=N=50) to closed (Z=50,N=82) shells). The static and dynami…

In-Medium Similarity Renormalization Group with Chiral Two- Plus Three-Nucleon Interactions

We use the recently proposed In-Medium Similarity Renormalization Group (IM-SRG) to carry out a systematic study of closed-shell nuclei up to $\nuc{Ni}{56}$, based on chiral two- plus three-nucleon interactions. We analyze the capabilities of the IM-SRG by comparing our results for the ground-state energy to Coupled Cluster calculations, as well as to quasi-exact results from the Importance-Truncated No-Core Shell Model. Using chiral two- plus three-nucleon Hamiltonians whose resolution scales are lowered by free-space SRG evolution, we obtain good agreement with experimental binding energies …

Recombination rates from potential models close to the unitary limit

We investigate universal behavior in the recombination rate of three bosons close to threshold. Using the He-He system as a reference, we solve the three-body Schrödinger equation above the dimer threshold for different potentials having large values of the two-body scattering length $a$. To this aim we use the hyperspherical adiabatic expansion and we extract the $S$-matrix through the integral relations recently derived. The results are compared to the universal form, $α\approx 67.1\sin^2[s_0\ln(κ_*a)+γ]$, for different values of $a$ and selected values of the three-body parameter $κ_*$. A g…