One-step replica symmetry breaking solution for fermionic Ising spin glass in a transverse field

The fermionic Ising spin glass models in a transverse field are investigated in a Grassmann path integral formalism. The Parisi's scheme of one-step replica symmetry breaking (RSB) is used within the static ansatz. This formalism has already been applied in a theory in which $m$ (Parisi's block-size parameter) is taken as a constant (PRB 72, 014447 (2005)). Now, it is extended to consider $m$ as a variational parameter. In this case, the results show that RSB is present when $T\to0$, in which the system is driven by quantum fluctuations.Comment: 8 pages, 3 figures, accepted for publication as a Brief Report in Phys. Rev.

Role of the transverse field in inverse freezing in the fermionic Ising spin-glass model

We investigate the inverse freezing in the fermionic Ising spin-glass (FISG) model in a transverse field $\Gamma$. The grand canonical potential is calculated in the static approximation, replica symmetry and one-step replica symmetry breaking Parisi scheme. It is argued that the average occupation per site $n$ is strongly affected by $\Gamma$. As consequence, the boundary phase is modified and, therefore, the reentrance associated with the inverse freezing is modified too.Comment: 6 pages, 3 figures, accepted for publication in PR

Budgetary Separation of Powers in the American States and the Tax Level: A Regression Discontinuity Analysis

A political regime has budgetary separation of powers if the power with the prerogative to raise taxes is not the full residual claimant of a tax increase. In the American states two conditions are needed: the governor must have the line item veto, and the political interests of the legislative majority and the governor must not be perfectly aligned. Political alignment between the executive and the legislative depends on the numbers of seats the governor's party controls in the state legislature; it changes discontinuously as we move from a unifed to a divided government. We use regression discontinuity design to establish a causal relation between a divided government and lower tax rates in states with line item veto. In states with block veto such relation is not present. We estimate the jump in the tax level at the discontinuity semiparametrically.Separation of powers, line item veto, tax level, regression discontinuity, semiparametric.

Labahitha nom.n., çàìåùàþùåå íàçâàíèå äëÿ Mystes Bristowe, 1938, ñ ïåðåîïèñàíèåì òèïîâîãî âèäà (Aranei: Filistatidae)

The monotypic genus Mystes Bristowe, 1938, and its type species, M. oonopiformis Bristowe, 1938, are redescribed based on the neotype male (designated here) and several females. The male is described for the first time and the female endogyne is illustrated for the first time. Morphological analysis reveals that the genus belongs to the Prithinae and is close to the Australian genera Wandella Gray, 1994 and Yardiella Gray, 1994. As the name Mystes is preoccupied by Mystes Champion, 1895 (Coleoptera: Melandryidae), we propose Labahitha nom.n. as a replacement name.Монотипичный род Mystes Bristowe, 1938, и его типовой вид M. oonopiformis Bristowe, 1938 переописываются по обозначенному здесь сам- цу-неотипу и нескольким самкам. Впервые для вида описываются самец и приводятся изображения эн- догины самки. Морфологические признаки этого рода указывают на то, что он принадлежит к под- сем. Prithinae и может быть близкородственным по отношению к Wandella Gray, 1994, и Yardiella Gray, 1994. Так как название Mystes преоккупировано ро- дом Mystes Champion, 1895 (Coleoptera: Melandryidae), мы предлагаем Labahitha nom. n. как замеща- ющее название.Fil: Zonstenin, Sergei L.. Steinhardt Museum Of Natural History, Tel-aviv Universi; IsraelFil: Marusik, Yuri M.. Institute For Biological Problems Of The North; RusiaFil: Fiorini de Magalhaes, Ivan Luiz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin

Pseudogap and the specific heat of high TcT_c superconductors

The specific heat of a two dimensional repulsive Hubbard model with local interaction is investigated. We use the two-pole approximation which exhibits explicitly important correlations that are sources of the pseudogap anomaly. The interplay between the specific heat and the pseudogap is the main focus of the present work. Our self consistent numerical results show that above the occupation $n_T\approx 0.85$, the specific heat starts to decrease due to the presence of a pseudogap in the density of states. We have also observed a two peak structure in the specific heat. Such structure is robust with respect to the Coulomb interaction $U$ but it is significantly affected by the occupation $n_T$. A detailed study of the two peak structure is carried out in terms of the renormalized quasi-particle bands. The role of the second nearest neighbor hopping on the specific heat behavior and on the pseudogap, is extensively discussed.Comment: 6 pages, 6 figures, accepted for publication in Solid State Communication

A van Hemmen-Kondo model for disordered strongly correlated electron systems

We present here a theoretical model in order to describe the competition between the Kondo effect and the spin glass behavior. The spin glass part of the starting Hamiltonian contains Ising spins with an intersite exchange interaction given by the local van Hemmen model, while the Kondo effect is described as usual by the intrasite exchange $J_K$. We obtain, for large $J_K$ values, a Kondo phase and, for smaller $J_K$ values, a succession, with decreasingComment: 14 pages, 4 figures, accepted for publication in Phys. Rev.