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

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

Specific heat of a non-local attractive Hubbard model

The specific heat of an attractive (interaction $G<0$) non-local Hubbard model is investigated. We use a two-pole approximation which leads to a set of correlation functions. In particular, the correlation function $\ $plays an important role as a source of anomalies in the normal state of the model. Our results show that for a giving range of$G$and$\delta$where$\delta=1-n_T$($n_T=n_{\uparrow}+n_{\downarrow}$), the specific heat as a function of the temperature presents a two peak structure. Nevertehelesss, the presence of a pseudogap on the anti-nodal points$(0,\pm\pi)$and$(\pm\pi,0)$ eliminates the two peak structure, the low temperature peak remaining. The effects of the second nearest neighbor hopping on the specific heat are also investigated.Comment: 5 pages, 7 figure

How to overcome limitations of analytic solutions when determining the direction of a gravitational wave using experimental data: an example with the schenberg detector

It has been commonly assumed that analytic solutions can efficiently provide the direction of a gravitational wave (GW) once sufficient data is available from gravitational wave detectors. Nevertheless, we identified that such analytic solutions (based on the GW matrix reconstruction) present unforeseen theoretical and practical limitations (indeterminacies) and that for certain incoming directions they are unable to recover the latter. We present here important indeterminacy cases as well as a mathematical procedure that reduces such indeterminacies. Also, we developed a method that requires the least computational power to retrieve GW directions and which can be applied to any system of detectors able to reconstruct the GW matrix. As a test for the method, we used simulated data of the spherical, resonant mass GW detector Schenberg, which involves five oscillating modes and six transducer readouts. The results show that this method canceled indeterminacies out satisfactorily.University of Florida, Department of Physics 2001 Museum Road, 32611-8440 Gainesville, FL, USAFederal University of Sao Paulo, Department of Exact and Earth Sciences Rua Sao Nicolau 120, 09913-030 Diadema, SP, BrazilFederal University of Sao Paulo, Department of Exact and Earth Sciences Rua Sao Nicolau 120, 09913-030 Diadema, SP, BrazilWeb of Scienc

Computation of schenberg response function by using finite element modelling

Schenberg is a detector of gravitational waves resonant mass type, with a central frequency of operation of 3200 Hz. Transducers located on the surface of the resonating sphere, according to a distribution half-dodecahedron, are used to monitor a strain amplitude. The development of mechanical impedance matchers that act by increasing the coupling of the transducers with the sphere is a major challenge because of the high frequency and small in size. The objective of this work is to study the Schenberg response function obtained by finite element modeling (FEM). Finnaly, the result is compared with the result of the simplified model for mass spring type system modeling verifying if that is suitable for the determination of sensitivity detector, as the conclusion the both modeling give the same results.Sao Paulo Federal Institute Rua Pedro Vicente 625, 01109-010 Sao Paulo, SP, BrazilFederal University of Sao Paulo, Department of Exact and Earth Sciences Rua Sao Nicolau 120, 09913-030 Diadema, SP, BrazilFederal University of Sao Paulo, Department of Exact and Earth Sciences Rua Sao Nicolau 120, 09913-030 Diadema, SP, BrazilWeb of Scienc

Is zoning the solution to the UK housing crisis?

Although housing crises are rooted in both demand-side pressures and supply-side blockages, perceived regulatory impediments to building new homes are the softest target for policy reform. Critics argue that the English planning system’s case-by-case consideration of development applications hands excessive power to existing homeowners, who regularly veto those applications, thereby generating uncertainty for the development sector, impeding supply, and amplifying wealth inequalities. Drawing on interviews with planning and development actors, this paper explores the potential of rules-based zoning, in which consultation is restricted to plan-making and compliant applications proceed ‘automatically’, to address the supply sub-component of the housing crisis

Antiferromagnetic Ising spin glass competing with BCS pairing interaction in a transverse field

The competition among spin glass (SG), antiferromagnetism (AF) and local pairing superconductivity (PAIR) is studied in a two-sublattice fermionic Ising spin glass model with a local BCS pairing interaction in the presence of an applied magnetic transverse field $\Gamma$. In the present approach, spins in different sublattices interact with a Gaussian random coupling with an antiferromagnetic mean $J_0$ and standard deviation $J$. The problem is formulated in the path integral formalism in which spin operators are represented by bilinear combinations of Grassmann variables. The saddle-point Grand Canonical potential is obtained within the static approximation and the replica symmetric ansatz. The results are analysed in phase diagrams in which the AF and the SG phases can occur for small $g$ ($g$ is the strength of the local superconductor coupling written in units of $J$), while the PAIR phase appears as unique solution for large $g$. However, there is a complex line transition separating the PAIR phase from the others. It is second order at high temperature that ends in a tricritical point. The quantum fluctuations affect deeply the transition lines and the tricritical point due to the presence of $\Gamma$.Comment: 16 pages, 6 figures, accepted Eur. Phys. J.