A relation between moduli space of D-branes on orbifolds and Ising model

We study D-branes transverse to an abelian orbifold C^3/Z_n Z_n. The moduli space of the gauge theory on the D-branes is analyzed by combinatorial calculation based on toric geometry. It is shown that the calculation is related to a problemto count the number of ground states of an antiferromagnetic Ising model. The lattice on which the Ising model is defined is a triangular one defined on the McKay quiver of the orbifold.Comment: 20 pages, 13 figure

Fair Housing Act: Discrimination in the Distribution of Home Financing

Laufman v. Oakley Building and Loan Co., 408 F. Supp. 489 (S.D. Ohio 1976) In February of 1976, Federal Judge David S. Porter of the Western Division of the Southern District of Ohio handed down a decision which significantly affects home financing organizations in this country. The ruling in Laufman v. Oakley Building and Loan Co., marked the first federal court decision on redlining, that is, refusal to make mortgage loans on residential property in a racially transitional neighborhood, regardless of the prospective borrower\u27s creditworthiness or the condition of the borrower\u27s property. Judge Porter held that redlining is illegal under the Civil Rights Act of 1968. The purpose of Title VIII of the 1968 Civil Rights Act, better known as the Fair Housing Act, is clearly expressed in the legislation\u27s first sentence: It is the policy of the United States to provide, within constitutional limitations, for fair housing throughout the United States

A deformed QRPA formalism for single and two-neutrino double beta decay

We use a deformed QRPA formalism to describe simultaneously the energy distributions of the single beta Gamow-Teller strength and the two-neutrino double beta decay matrix elements. Calculations are performed in a series of double beta decay partners with A = 48, 76, 82, 96, 100, 116, 128, 130, 136 and 150, using deformed Woods-Saxon potentials and deformed Skyrme Hartree-Fock mean fields. The formalism includes a quasiparticle deformed basis and residual spin-isospin forces in the particle-hole and particle-particle channels. We discuss the sensitivity of the parent and daughter Gamow-Teller strength distributions in single beta decay, as well as the sensitivity of the double beta decay matrix elements to the deformed mean field and to the residual interactions. Nuclear deformation is found to be a mechanism of suppression of the two-neutrino double beta decay. The double beta decay matrix elements are found to have maximum values for about equal deformations of parent and daughter nuclei. They decrease rapidly when differences in deformations increase. We remark the importance of a proper simultaneous description of both double beta decay and single Gamow-Teller strength distributions. Finally, we conclude that for further progress in the field it would be useful to improve and complete the experimental information on the studied Gamow-Teller strengths and nuclear deformations.Comment: 33 pages, 19 figures. To be published in Phys. Rev.

Weak Interaction Rates Of sd-Shell Nuclei In Stellar Environment Calculated in the Proton-Neutron Quasiparticle Random Phase Approximation

Allowed weak interaction rates for sd-shell nuclei in stellar environment are calculated using a generalized form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. Twelve different weak rates are calculated for each nucleus as a function of temperature and density. This project consists of calculation of weak rates for a total of 709 nuclei with masses ranging from A = 18 to 100. This paper contains calculated weak rates for sd-shell nuclei. The calculated capture and decay rates take into consideration the latest experimental energy levels and ft value compilations. The results are also compared with earlier works. Particle emission processes from excited states, previously ignored, are taken into account, and are found to significantly affect some beta decay rates.Comment: 64 pages, 17 figures, rate tables are presented in an abbreviated form to save space. Complete rate tables can be seen in the original pape

Stepwise Projection: Toward Brane Setups for Generic Orbifold Singularities

The construction of brane setups for the exceptional series E6,E7,E8 of SU(2) orbifolds remains an ever-haunting conundrum. Motivated by techniques in some works by Muto on non-Abelian SU(3) orbifolds, we here provide an algorithmic outlook, a method which we call stepwise projection, that may shed some light on this puzzle. We exemplify this method, consisting of transformation rules for obtaining complex quivers and brane setups from more elementary ones, to the cases of the D-series and E6 finite subgroups of SU(2). Furthermore, we demonstrate the generality of the stepwise procedure by appealing to Frobenius' theory of Induced Representations. Our algorithm suggests the existence of generalisations of the orientifold plane in string theory.Comment: 22 pages, 3 figure

Shell Model Study of the Double Beta Decays of 76^{76}Ge, 82^{82}Se and 136^{136}Xe

The lifetimes for the double beta decays of $^{76}$Ge, $^{82}$Se and $^{136}$Xe are calculated using very large shell model spaces. The two neutrino matrix elements obtained are in good agreement with the present experimental data. For $<1$ eV we predict the following upper bounds to the half-lives for the neutrinoless mode: $T^{(0\nu)}_{1/2}(Ge) > 1.85\,10^{25} yr.$, $T^{(0\nu)}_{1/2}(Se) > 2.36\,10^{24} yr.$ and $T^{(0\nu)}_{1/2}(Xe) > 1.21\,10^{25} yr$. These results are the first from a new generation of Shell Model calculations reaching O(10$^{8}$) dimensions

Neutrino Opacities in Neutron Stars with Kaon Condensates

The neutrino mean free paths in hot neutron-star matter are obtained in the presence of kaon condensates. The kaon-induced neutrino absorption process, which is allowed only in the presence of kaon condensates, is considered for both nondegenerate and degenerate neutrinos. The neutrino mean free path due to this process is compared with that for the neutrino-nucleon scattering. While the mean free path for the kaon-induced neutrino absorption process is shown to be shorter than the ordinary two-nucleon absorption process by several orders of magnitude when temperature is not very high, the neutrino-nucleon scattering process has still a dominant contribution to the neutrino opacity. Thus, the kaon-induced neutrino absorption process has a minor effect on the thermal and dynamical evolution of protoneutron stars.Comment: 35 pages, 4 figure

Energy funneling in a bent chain of Morse oscillators with long-range coupling

A bent chain of coupled Morse oscillators with long-range dispersive interaction is considered. Moving localized excitations may be trapped in the bending region. Thus chain geometry acts like an impurity. An energy funneling effect is observed in the case of random initial conditions.Comment: 6 pages, 12 figures. Submitted to Physical Review E, Oct. 13, 200