Deformed nuclear density distributions derived from an energy functional

An energy functional is used to calculate non-spherical density distributions of protons and neutrons in a nucleus. Results are presented for the deformed region of 150 ≦ A ≦ 190.     

Neutron halos in hypernuclei

Properties of single- Λ and double- Λ hypernuclei for even-N Ca isotopes ranging from the proton dripline to the neutron dripline are studied using the relativistic continuum Hartree-Bogoliubov theory with a zero-range pairing interaction. Compared with ordinary nuclei, the addition of one or two Λ-hyperons lowers the Fermi level. The predicted neutron dripline nuclei are, respectively, ⁷⁵ _ΛCa and ⁷⁶ _2ΛCa, as the additional attractive force provided by the Λ-N interaction shifts nuclei from outside to inside the dripline. Therefore, the last bound hypernuclei have two more neutrons than the corresponding ordinary nuclei. Based on the analysis of two-neutron separation energies, neutron single-particle energy levels, the contribution of continuum and nucleon density distribution, giant halo phenomena due to the pairing correlation, and the contribution from the continuum are suggested to exist in Ca hypernuclei similar to those that appear in ordinary Ca isotopes. Received: 21 October 2002 / Accepted: 11 January 2003 / Published online: 8 April 2003     

Proton halos in exotic light nuclei

The current study on proton halos in exotic light nuclei is reviewed and discussed. We place emphasis on the newly discovered proton halo in ²³Al. A measurement of the reaction cross section of N=10 isotones and Z=13 isotopes is performed at Lanzhou in China. An abnormal increase in the reaction cross section is observed for ²³Al. This abnormal increase, combined with other data, strongly suggests that there is a proton halo in ²³Al. The possible cause for a proton halo in ²³Al is analyzed, and it is found that deformation can be important for it. Other candidates for proton halos are predicted.     

Possible existence of massive neutrino halos

A simple analysis of parameters for a system of self-gravitating massive neutrinos is presented. The possibility of massive halos in galaxies and clusters of galaxies is discussed.     

Dynamic colloidal stabilization by nanoparticle halos

We explore the conditions under which colloids can be stabilized by the addition of smaller particles. The largest repulsive barriers between colloids occur when the added particles repel each other with soft interactions, leading to an accumulation near the colloid surfaces. At lower densities these layers of mobile particles (nanoparticle halos) result in stabilization, but when too many are added, the interactions become attractive again. We systematically study these effects--accumulation repulsion, reentrant attraction, and bridging--by accurate integral equation techniques.     

Deformed supersymmetric oscillators

We construct and discuss the Fock-space representation and the number operator for a deformed supersymmetric oscillator with “peculiar” statistics. We suggest a possible generalization to multimode deformed oscillators.     

Resolving infall caustics in dark matter halos

It has been found that the phase space of dark matter particles assembling a galactic halo in cosmological N-body simulations well defines the fine grained structure. Recently accreted particles form distinctive velocity streams with high density contrast. For a fixed observer position, these streams lead to peaks in the velocity distribution. Overall structure is close to that emerging in the secondary infall model.     

Solitonic axion condensates modeling dark matter halos

Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose–Einstein type condensates could provide a viable soliton type interpretation of the DM ‘bullets’ observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein–Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two ‘lump’ type solitons.     

The spacetime associated with galactic dark matter halos

We show how an adequate post-Newtonian generalization can be obtained for Newtonian dark matter halos associated with an empiric density profile. Applying this approach to halos that follow from the well known numerical simulations of Navarro, Frenk and White (NFW), we derive all dynamical variables and show that NFW halos approximately follow an ideal gas type of equation of state which fits very well to a polytropic relation in the region outside the core. This fact suggests that outer regions of NFW halos might be related to equilibrium states in the non-extensive Statistical Mechanics formalism proposed by Tsallis.     

Neutron halos in heavy nuclei-relativistic mean field approach

Assuming a simple spherical relativistic mean field model of the nucleus, we estimate the width of the antiproton-neutron annihilation (Γ_n) and the width of antiproton-proton (Γ_p) annihilation, in an antiprotonic atom system. This allows us to determine the halo factor f, which is then discussed in the context of experimental data obtained in measurements recently done on LEAR utility at CERN. Another quantity which characterizes the deviation of the average nuclear densities ratio from the corresponding ratio of the homogeneous densities is introduced too. It was shown that it is also a good indicator of the neutron halo. The results are compared to experimental data as well as to the data of the simple liquid droplet model of the nuclear densities. The single particle structure of the nuclear density tail is discussed also.     

变形对称双阱势

利用变形双曲函数,将对称双阱势推广为变形对称双阱势模型.证明了该势模型是五参量指数型势模型的特例.运用超对称WKB近似和五参量指数型势模型的能谱公式,获得了变形对称双阱势模型的能谱公式.     

Theoretical research on proton halos in exotic nuclei

Very neutron-deficient nuclei are investigated with Woods-Saxon potentials,especially the newly measured A =2Z-1 nucleus ~(65)As [X.L.Tu et al.,Phys.Rev.Lett.106,112501(2011)],where the experimental proton separation energy is obtained as-90(85) keV for the first time.Careful consideration is given to quasibound protons with outgoing Coulomb wave boundary conditions.The observed proton halos in the first excited state of ~(17)F and in the ground states of ~(26,27,28)P are reproduced well,and predictions of proton halos are made for the ground states of ~(56,57)Cu and ~(65)As.The sensitivity of the results to the proton separation energy is discussed in detail,together with the effect of the l=1 centrifugal barrier on proton halos.     

Deformed giant quark nuclei

We examined the dependence of the mass of giant quark nuclei on quadrupole surface deformations. We find that also for large deformations the possiblity exists that the mass of very heavy giant quark nuclei is lower than that of the corresponding ordinary nuclei, leading to a dissolution of nuclei into quarks in very heavy nuclear collision systems.     

Impact of large-angle scattering on diffusively backscattered halos

We discuss the impact of large-angle scattering events in highly forward-scattering media on the spatial distribution of the diffusively reflected light. We show that, even for highly forward-scattering media, the reflected light near the incident beam axis is strongly dependent on the small number of large-angle scattering events. Reliable modeling of near-axis reflection thus requires accurate knowledge of the scattering phase function's behavior at large angles.     

Flat rotation curves in scalar field galaxy halos

We start with a model where the dark matter is of scalar field nature, which condensates and form the dark halos of galaxies. In this work we study Bose–Einstein condensates (BEC) where the scalar field particles are in many different states, and not only in the ground state, as in a realistic BEC. We find that this model is in better agreement with the rotation curves of galaxies than previous models with scalar field dark matter.