A Model of Equilibrium Institutions

Institutions that serve the interests of an elite are often cited as an important reason for poor economic performance. This paper builds a model of institutions that allocate resources and power to maximize the payoff of an elite, but where any group that exerts sufficient fighting effort can launch a rebellion that destroys the existing institutions. The rebels are then able to establish new institutions as a new elite, which will similarly face threats of rebellion. The paper analyses the economic consequences of the institutions that emerge as the equilibrium of this struggle for power. High levels of economic activity depend on protecting private property from expropriation, but the model predicts this can only be achieved if power is not as concentrated as the elite would like it to be, ex post. Power sharing endogenously enables the elite to act as a government committed to property rights, which would otherwise be time inconsistent. But sharing power entails sharing rents, so in equilibrium power is too concentrated, leading to inefficiently low investment.institutions, political economy, power struggle, property rights, time inconsistency

Pad\'e approximation and glueball mass estimates in 3d and 4d with N_c = 2,3 colors

A Pad\'e approximation approach, rooted in an infrared moment technique, is employed to provide mass estimates for various glueball states in pure gauge theories. The main input in this analysis are theoretically well-motivated fits to lattice gluon propagator data, which are by now available for both SU(2) and SU(3) in 3 and 4 space-time dimensions. We construct appropriate gauge invariant and Lorentz covariant operators in the (pseudo)scalar and (pseudo)tensor sector. Our estimates compare reasonably well with a variety of lattice sources directly aimed at extracting glueball masses.Comment: 11 pages, 5 .png figures. v2: extra figure, calculational details and references; improved presentation and title. Version to appear in Phys.Lett.

Long-distance radiative coupling between quantum dots in photonic crystal dimers

We study the mutual interaction between two identical quantum dots coupled to the normal modes of two-site photonic crystal molecules in a planar waveguide geometry, i.e. photonic crystal dimers. We find that the radiative coupling between the two quantum emitters is maximized when they are in resonance with either the bonding or the antibonding modes of the coupled cavity system. Moreover, we find that such effective interdot coupling is sizable, in the meV range, and almost independent from the cavities distance, as long as a normal mode splitting exceeding the radiative linewidth can be established (strong cavity-cavity coupling condition). In realistic and high quality factor photonic crystal cavity devices, such distance can largely exceed the emission wavelength, which is promising for long distance entanglement generation between two qubits in an integrated nanophotonic platform. We show that these results are robust against position disorder of the two quantum emitters within their respective cavities.Comment: 10 pages, 6 figure

Contribuição para a popularização dos Sistemas de Informações geográficas.

Geographical information systems are becoming a common information management and analysis tool used in a wide and growing range of application fields. The popularization of GIS techniques request the easy-to-use softwares. From among 12 freeware softwares evaluated, Hypercube (a freeware program produced by the US Army Corps of Engineers Topographic Engineering Center) was considered the most efficient to perform functions related to filter, warp, mosaic, reformat, calibrate, and combine multi and hyper-spectral imagery. FGIS, according with the same criteria, was considered the most efficient to perform shapefile editing programs, digitizer and GIS data query tool

Massive photons and Dirac monopoles: electric condensate and magnetic confinement

We use the generalized Julia-Toulouse approach (GJTA) for condensation of topological currents (charges or defects) to argue that massive photons can coexist consistently with Dirac monopoles. The Proca theory is obtained here via GJTA as a low energy effective theory describing an electric condensate and the mass of the vector boson is responsible for generating a Meissner effect which confines the magnetic defects in monopole-antimonopole pairs connected by physical open magnetic vortices described by Dirac brane invariants, instead of Dirac strings.Comment: 6 pages, version accepted for publication in Physics Letters

Accessing the topological susceptibility via the Gribov horizon

The topological susceptibility, $\chi^4$, following the work of Witten and Veneziano, plays a key role in identifying the relative magnitude of the $\eta^{\prime}$ mass, the so-called $U(1)_{A}$ problem. A nonzero $\chi^4$ is caused by the Veneziano ghost, the occurrence of an unphysical massless pole in the correlation function of the topological current. In a recent paper (Phys.Rev.Lett.114 (2015) 24, 242001), an explicit relationship between this Veneziano ghost and color confinement was proposed, by connecting the dynamics of the Veneziano ghost, and thus the topological susceptibility, with Gribov copies. However, the analysis is incompatible with BRST symmetry (Phys.Rev.D 93 (2016) no.8, 085010). In this paper, we investigate the topological susceptibility, $\chi^4$, in SU(3) and SU(2) Euclidean Yang-Mills theory using an appropriate Pad\'e approximation tool and a non-perturbative gluon propagator, within a BRST invariant framework and by taking into account Gribov copies in a general linear covariant gauge.Comment: 17 pages, 4 figures. v2: corrected typos, new figures, improved style of presentatio

SU(2) x U(1) Yang-Mills theories in 3d with Higgs field and Gribov ambiguity

We study the structure of the gauge propagators of a 3d version of the electroweak interaction in terms of the Higgs vacuum expectation value., of the non-Abelian gauge coupling g, and of the Abelian gauge coupling g', when nonperturbative effects related to the non-Abelian gauge fixing are introduced by means of an adapted path integral measure. In the perturbative regime of small nonAbelian coupling g and sufficiently large, nu the well-known standard Z and W propagators are recovered, together with a massless photon. In general, depending on the relative magnitudes of g, g' and., we uncover a quite different propagator structure. In a later stage of research, the results here derived can be used to study the associated phase diagram in more depth