On the uniqueness of the unitary representations of the non commutative Heisenberg-Weyl algebra

In this paper we discuss the uniqueness of the unitary representations of the non commutative Heisenberg-Weyl algebra. We show that, apart from a critical line for the non commutative position and momentum parameters, the Stone-von Neumann theorem still holds, which implies uniqueness of the unitary representation of the Heisenberg-Weyl algebra.Comment: 4 page

Hamiltonian reduction and supersymmetric mechanics with Dirac monopole

We apply the technique of Hamiltonian reduction for the construction of three-dimensional ${\cal N}=4$ supersymmetric mechanics specified by the presence of a Dirac monopole. For this purpose we take the conventional ${\cal N}=4$ supersymmetric mechanics on the four-dimensional conformally-flat spaces and perform its Hamiltonian reduction to three-dimensional system. We formulate the final system in the canonical coordinates, and present, in these terms, the explicit expressions of the Hamiltonian and supercharges. We show that, besides a magnetic monopole field, the resulting system is specified by the presence of a spin-orbit coupling term. A comparison with previous work is also carried out.Comment: 9 pages, LaTeX file, PACS numbers: 11.30.Pb, 03.65.-w, accepted for publication in PRD; minor changes in the Conclusion, the Bibliography and the Acknowledgemen

The geometry of N=4 twisted string

We compare N=2 string and N=4 topological string within the framework of the sigma model approach. Being classically equivalent on a flat background, the theories are shown to lead to different geometries when put in a curved space. In contrast to the well studied Kaehler geometry characterising the former case, in the latter case a manifold has to admit a covariantly constant holomorphic two-form in order to support an N=4 twisted supersymmetry. This restricts the holonomy group to be a subgroup of SU(1,1) and leads to a Ricci--flat manifold. We speculate that, the N=4 topological formalism is an appropriate framework to smooth down ultraviolet divergences intrinsic to the N=2 theory.Comment: 20 pages, LaTe

On Quantum Special Kaehler Geometry

We compute the effective black hole potential V of the most general N=2, d=4 (local) special Kaehler geometry with quantum perturbative corrections, consistent with axion-shift Peccei-Quinn symmetry and with cubic leading order behavior. We determine the charge configurations supporting axion-free attractors, and explain the differences among various configurations in relations to the presence of ``flat'' directions of V at its critical points. Furthermore, we elucidate the role of the sectional curvature at the non-supersymmetric critical points of V, and compute the Riemann tensor (and related quantities), as well as the so-called E-tensor. The latter expresses the non-symmetricity of the considered quantum perturbative special Kaehler geometry.Comment: 1+43 pages; v2: typo corrected in the curvature of Jordan symmetric sequence at page 2

Single Wall Nanotubes: Atomic Like Behaviour and Microscopic Approach

Recent experiments about the low temperature behaviour of a Single Wall Carbon Nanotube (SWCNT) showed typical Coulomb Blockade (CB) peaks in the zero bias conductance and allowed us to investigate the energy levels of interacting electrons. Other experiments confirmed the theoretical prediction about the crucial role which the long range nature of the Coulomb interaction plays in the correlated electronic transport through a SWCNT with two intramolecular tunneling barriers. In order to investigate the effects on low dimensional electron systems due to the range of electron electron repulsion, we introduce a model for the interaction which interpolates well between short and long range regimes. Our results could be compared with experimental data obtained in SWCNTs and with those obtained for an ideal vertical Quantum Dot (QD). For a better understanding of some experimental results we also discuss how defects and doping can break some symmetries of the bandstructure of a SWCNT.Comment: 8 pages, 4 figure

Restoring an eroded legitimacy: the adaptation of nonfinancial disclosure after a scandal and the risk of hypocrisy

Purpose \u2013 This study contributes to the literature on hypocrisy in corporate social responsibility by investigating how organizations adapt their nonfinancial disclosure after a social, environmental or governance scandal. Design/methodology/approach \u2013 The present research employs content analysis of nonfinancial disclosures by 11 organizations during a 3-year timespan to investigate how they responded to major scandals in terms of social, environmental and sustainability reporting and a content analysis of independent counter accounts to detect the presence of views that contrast with the corporate disclosure and suggest hypocritical behaviors. Findings \u2013 Four patterns in the adaptation of reporting \u2013 genuine, allusive, evasive, indifferent \u2013 emerge from information collected on scandals and socially responsible actions. The type of scandal and cultural factors can influence the response to a scandal, as environmental and social scandal can attract more scrutiny than financial scandals. Companies exposed to environmental and social scandals are more likely to disclose information about the scandal and receive more coverage by external parties in the form of counter accounts. Originality/value \u2013 Using a theoretical framework based on legitimacy theory and organizational hypocrisy, the present research contributes to the investigation of the adaptation of reporting when a scandal occurs and during its aftermath

Non-supersymmetric Extremal RN-AdS Black Holes in N=2 Gauged Supergravity

We investigate extremal Reissner-Nordstrom-AdS black holes in four-dimensional N=2 abelian gauged supergravity. We find a new attractor equation which is not reduced to the one in the asymptotically flat spacetime. Focusing on so-called the T^3-model with a single neutral vector multiplet, we obtain non-supersymmetric extremal Reissner-Nordstrom-AdS black hole solutions with regular event horizon in the D0-D4 and the D2-D6 charge configurations. The negative cosmological constant emerges even without the Fayet-Iliopoulos parameters. Furthermore, we also argue the formal description of the non-supersymmetric black hole solutions of the T^3-model and the STU-model in generic configurations.Comment: 23 pages, accepted version in JHE

The Visible and Near Infrared module of EChO

The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument had to be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude Mv= 9-12 and to see contrasts of the order of 10-4 - 10-5 necessary to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR is a spectrometer in a cross-dispersed configuration, covering the 0.4-2.5 micron spectral range with a resolving power of about 330 and a field of view of 2 arcsec. It is functionally split into two channels respectively working in the 0.4-1 and 1.0-2.5 micron spectral ranges. Such a solution is imposed by the fact the light at short wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The spectrometer makes use of a HgCdTe detector of 512 by 512 pixels, 18 micron pitch and working at a temperature of 45K as the entire VNIR optical bench. The instrument has been interfaced to the telescope optics by two optical fibers, one per channel, to assure an easier coupling and an easier colocation of the instrument inside the EChO optical bench.Comment: 26 page

Multi-Centered Black Hole Flows

We describe the systematical construction of the first order formalism for multi-centered black holes with flat three dimensional base-space, within the so-called $T^{3}$ model of N=2, D=4 ungauged Maxwell-Einstein supergravity. The three possible flow classes (BPS, composite non-BPS and almost-BPS) are analyzed in detail, and various solutions, such as single-centered (static or under-rotating) and all known multi-centered black holes, are recovered in this unified framework. We also consider the possibility of obtaining new solutions. The almost-BPS class is proved to split into two general sub-classes, corresponding to a positive or negative value of the duality-invariant polynomial for the total charge; the well known almost BPS system is shown to be a particular solution of the second sub-class.Comment: 17 pages,no figure

Applicazione di una metodologia sistemica per la valutazione della suscettibilità al dissesto dei versanti tufacei del Comune di Napoli

It is here described a study which deals with the analysis of landslide susceptibility related to the tuff slopes in Naples, Italy. This type of instability has an important role in the hydro-geological emergencies which affected the city both in historical times and in recent years. The developed GIS algorithm is based on a system model, named RES (Rock Engineering Systems – Hudson, 1992), which accounts for the interactions among the factors involved into the analysed system. Survey campaigns and in situ tests have been carried up to collect the data necessary to allow the characterization of rock masses using classification methods recognized by the International Society of Rock Mechanics. Finally, using the RES a landslide susceptibility index has been estimated for the tuff slopes, which allowed to create the related map. The work here illustrated is part of a larger framework which aim is to create an Integrated Geographic Information System to study the hydro-geological risk in Naples’ territory. This System, hopefully enriched with new thematic layers, while providing the basis for future researches in the field, can also provide local decision-makers and community planners with the scientific and technological support for decisions involving management of risks and urban development