Brueckner Rearrangement Effects in Λ5^5_\LambdaHe and ΛΛ6^6_{\Lambda\Lambda}He

Rearrangement effects in light hypernuclei are investigated in the framework of the Brueckner theory. We can estimate without detailed numerical calculations that the energy of the $\alpha$-core is reduced by more than 2.5 MeV when the $\Lambda$ adheres to $^4$He to form $^5_\Lambda$He. Similar assessment of rearrangement contributions is essential to deduce the strength of $\Lambda\Lambda$ interaction from experimentally observed $\Delta B_{\Lambda\Lambda}$. The recently observed experimental value of $\sim$ 1 MeV for the $\Delta B_{\Lambda\Lambda}$ of \hll suggests that the matrix element of $$ in \hll is around -2 MeV.Comment: 7 pages, to appear in Phys. Rev.

Faddeev calculations for the A=5,6 Lambda-Lambda hypernuclei

Faddev calculations are reported for Lambda-Lambda-5H, Lambda-Lambda-5He and Lambda-Lambda-6He in terms of two Lambda hyperons plus the respective nuclear clusters, using Lambda-Lambda central potentials considered in past non-Faddeev calculations of Lambda-Lambda-6He. The convergence with respect to the partial-wave expansion is studied, and comparison is made with some of these Lambda-Lambda hypernuclear calculations. The Lambda-Lambda Xi-N mixing effect is briefly discussed.Comment: submitted for publicatio

Can slow roll inflation induce relevant helical magnetic fields?

We study the generation of helical magnetic fields during single field inflation induced by an axial coupling of the electromagnetic field to the inflaton. During slow roll inflation, we find that such a coupling always leads to a blue spectrum with $B^2(k) \propto k$, as long as the theory is treated perturbatively. The magnetic energy density at the end of inflation is found to be typically too small to backreact on the background dynamics of the inflaton. We also show that a short deviation from slow roll does not result in strong modifications to the shape of the spectrum. We calculate the evolution of the correlation length and the field amplitude during the inverse cascade and viscous damping of the helical magnetic field in the radiation era after inflation. We conclude that except for low scale inflation with very strong coupling, the magnetic fields generated by such an axial coupling in single field slow roll inflation with perturbative coupling to the inflaton are too weak to provide the seeds for the observed fields in galaxies and clusters.Comment: 33 pages 6 figures; v4 to match the accepted version to appear in JCA

Light Lambda-Lambda Hypernuclei and the Onset of Stability for Lambda-Xi Hypernuclei

New Faddeev-Yakubovsky calculations for light Lambda-Lambda hypernuclei are presented in order to assess the self consistency of the Lambda-Lambda hypernuclear binding-energy world data and the implied strength of the Lambda-Lambda interaction, in the wake of recent experimental reports on Lambda-Lambda-4H and Lambda-Lambda-6He. Using Gaussian soft-core simulations of Nijmegen one-boson-exchange model interactions, the Nijmegen soft-core model NSC97 simulations are found close to reproducing the recently reported binding energy of Lambda-Lambda-6He, but not those of other species. For stranger systems, Faddeev calculations of light Lambda-Xi hypernuclei, using a simulation of the strongly attractive Lambda-Xi interactions due to the same model, suggest that Lambda-Xi-6He marks the onset of nuclear stability for Xi hyperons.Comment: 5 pages, 3 postscript figures; fig.2 replaced, minor changes, accepted as Rapid Communication in PR

Age and growth of marbled sole Pleuronectes yokohamae in Kikonai Bay, Hokkaido, Japan

Age and growth of marbled sole Pleuronectes yokohamae werer estimated from growth increments in otolith. The samples were collected with commercial set nets and an experimental bottom trawl net in Kikonai Bay and the nearby waters, southern coast of Hokkaido, from May 1994 to July 1995. Monthly changes in the percentage occurrence of oltoliths with translucent edge in one band and the marginal increments on the other hand verified that the translucent zone was formed once a year after their spawning season in May, indicating availability of outer margin of translucent zone as an annulus. The regression method as well as Fraser-Lee's method was used to estimate the back-calculated lengths. Growth of marbled sole was expressed by the von Bertalanffy asymptotic growth function: TLt=361.78[1-exp-0.390(t-0.098)) for males and TLt=438.15[1-exp-0.323(t-0.145)) for females using back-calculated lengths by the regression method and TLt=367.04[1-exp-0.388(t-0.114))] for males and TLt=436.05[1-exp-0.323(t-0.147)) for females by the Fraser-Lee's method, where TLt is total length (millimeters) at estimated age t.The theoretical lengths predicted by these two methods at all estimated ages were very similar. It was found that the growth rate of marbled sole in this study area was relatively high compared to those obtained in the Inland Sea of Japan as. However, the highest growth rate was observed with regard to the population off Fukushima Prefecture, although the bottom water temperatures were similar to those in Kikonai Bay. It is inferred that the geographical variation in the growth rates of marbled sole is influenced by the hydrographic and food conditions

Signatures of Spin and Charge Energy Scales in the Local Moment and Specific Heat of the Two-Dimensional Hubbard Model

Local moment formation driven by the on--site repulsion $U$ is one of the most fundamental features in the Hubbard model. At the simplest level, the temperature dependence of the local moment is expected to have a single structure at $T \sim U$, reflecting the suppression of the double occupancy. In this paper we show new low temperature Quantum Monte Carlo data which emphasize that the local moment also has a signature at a lower energy scale which previously had been thought to characterize only the temperatures below which moments on {\it different} sites begin to correlate locally. We discuss implications of these results for the structure of the specific heat, and connections to quasiparticle resonance and pseudogap formation in the density of states.Comment: 13 pages, 19 figure

Star and Planet Formation with ALMA: an Overview

Submillimeter observations with ALMA will be the essential next step in our understanding of how stars and planets form. Key projects range from detailed imaging of the collapse of pre-stellar cores and measuring the accretion rate of matter onto deeply embedded protostars, to unravelling the chemistry and dynamics of high-mass star-forming clusters and high-spatial resolution studies of protoplanetary disks down to the 1 AU scale.Comment: Invited review, 8 pages, 5 figures; to appear in the proceedings of "Science with ALMA: a New Era for Astrophysics". Astrophysics & Space Science, in pres

Fabrication and electrical characterization of 0.55 eV n-on-p InGaAs thermophotovoltaic devices

Results are presented on the characterization and testing of lattice mismatched 0.55 eV InGaAs/InP thermophotovoltaic (TPV) cells. A robust cell fabrication technique amenable to high throughput production is presented. A versatile light and dark I-V set up capable of fast screening of the TPV cells and an innovative approach for screening high performance cells are presented. The authors also report on the effect of lattice matched InAsP and InAlAs back surface field on the performance of the TPV cells