Mean Field Theoretical Structure of He and Be Isotopes

The structures of He and Be even-even isotopes are investigated using an axially symmetric Hartree-Fock approach with a Skyrme-IIIls mean field potential. In these simple HF calculations, He and Be isotopes appear to be prolate in their ground states and Be isotopes have oblate shape isomeric states. It is also shown that there exists a level crossing when the nuclear shape changes from the prolate state to the oblate state. The single neutron levels of Be isotopes exhibit a neutron magic number 6 instead of 8 and show that the level inversion between 1/2- and 1/2+ levels occurs only for a largely deformed isotope. Protons are bound stronger in the isotope with more neutrons while neutron levels are somewhat insensitive to the number of neutrons and thus the nuclear size and also the neutron skin become larger as the neutron number increases. In these simple calculations with Skyrme-IIIls interaction no system with a clear indication of neutron halo was found among He and Be isotopes. Instead of it we have found 8He+2n, 2n+8He+2n, and 16Be+2n like chain structures with clusters of two correlated neutrons. It is also shown that 8He and 14Be in their ground states are below the neutron drip line in which all nucleons are bound with negative energy and that 16Be in its ground state is beyond the neutron drip line with two neutrons in positive energy levels.Comment: CM energy correction, 1 figure and more discussions adde

Quantization of anomaly coefficients in 6D N=(1,0)\mathcal{N}=(1,0) supergravity

We obtain new constraints on the anomaly coefficients of 6D $\mathcal{N}=(1,0)$ supergravity theories using local and global anomaly cancellation conditions. We show how these constraints can be strengthened if we assume that the theory is well-defined on any spin space-time with an arbitrary gauge bundle. We distinguish the constraints depending on the gauge algebra only from those depending on the global structure of the gauge group. Our main constraint states that the coefficients of the anomaly polynomial for the gauge group $G$ should be an element of $2 H^4(BG;\mathbb{Z}) \otimes \Lambda_S$ where $\Lambda_S$ is the unimodular string charge lattice. We show that the constraints in their strongest form are realized in F-theory compactifications. In the process, we identify the cocharacter lattice, which determines the global structure of the gauge group, within the homology lattice of the compactification manifold.Comment: 42 pages. v3: Some clarifications, typos correcte

A key to room-temperature ferromagnetism in Fe-doped ZnO: Cu

Successful synthesis of room-temperature ferromagnetic semiconductors, Zn$_{1-x}$Fe$_{x}$O, is reported. The essential ingredient in achieving room-temperature ferromagnetism in bulk Zn$_{1-x}$Fe$_{x}$O was found to be additional Cu doping. A transition temperature as high as 550 K was obtained in Zn$_{0.94}$Fe$_{0.05}$Cu$_{0.01}$O; the saturation magnetization at room temperature reached a value of $0.75 \mu_{\rm B}$ per Fe. Large magnetoresistance was also observed below $100$K.Comment: 11 pages, 4 figures; to appear in Appl. Phys. Let

Bias adjustment of satellite precipitation estimation using ground-based measurement: A case study evaluation over the southwestern United States

Reliable precipitation measurement is a crucial component in hydrologic studies. Although satellite-based observation is able to provide spatial and temporal distribution of precipitation, the measurements tend to show systematic bias. This paper introduces a grid-based precipitation merging procedure in which satellite estimates from the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS) are adjusted based on the Climate Prediction Center (CPC) daily rain gauge analysis. To remove the bias, the hourly CCS estimates were spatially and temporally accumulated to the daily 1°×1° scale, the resolution of CPC rain gauge analysis. The daily CCS bias was then downscaled to the hourly temporal scale to correct hourly CCS estimates. The bias corrected CCS estimates are called the adjusted CCS (CCSA) product. With the adjustment from the gauge measurement, CCSA data have been generated to provide more reliable high temporal/spatial-resolution precipitation estimates. In the case study, the CCSA precipitation estimates from the proposed approach are compared against ground-based measurements in high-density gauge networks located in the southwestern United States. © 2009 American Meteorological Society

Solar-neutrino reactions on deuteron in effective field theory

The cross sections for low-energy neutrino-deuteron reactions are calculated within heavy-baryon chiral perturbation theory employing cut-off regularization scheme. The transition operators are derived up to next-to-next-to-next-to-leading order in the Weinberg counting rules, while the nuclear matrix elements are evaluated using the wave functions generated by a high-quality phenomenological NN potential. With the adoption of the axial-current-four-nucleon coupling constant fixed from the tritium beta decay data, our calculation is free from unknown low-energy constants. Our results exhibit a high degree of stability against different choices of the cutoff parameter, a feature which indicates that, apart from radiative corrections, the uncertainties in the calculated cross sections are less than 1 %.Comment: 12 pages, 3 figures. Error estimation of higher order corrections detaile