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Genova, Italy

D'Elia M.,DellUniversity Pisa | Negro F.,DellUniversity Genoa
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We study the phase diagram of non-Abelian pure gauge theories in the presence of a topological θ term. The dependence of the deconfinement temperature on θ is determined on the lattice both by analytic continuation and by reweighting, obtaining consistent results. The general structure of the diagram is discussed on the basis of large-N considerations and of the possible analogies and dualities existing with the phase diagram of QCD in the presence of an imaginary baryon chemical potential. © 2013 American Physical Society. Source


D'Elia M.,DellUniversity Pisa | Mariti M.,DellUniversity Pisa | Negro F.,DellUniversity Genoa
Physical Review Letters | Year: 2013

We investigate two flavor quantum chromodynamics (QCD) in the presence of CP-odd electromagnetic background fields and determine, by means of lattice QCD simulations, the induced effective θ term to first order in E→·B→. We employ a rooted staggered discretization and study lattice spacings down to 0.1 fm and Goldstone pion masses around 480 MeV. In order to deal with a positive measure, we consider purely imaginary electric fields and real magnetic fields, and then exploit the analytic continuation. Our results are relevant to a description of the effective pseudoscalar quantum electrodynamics - QCD interactions. © 2013 American Physical Society. Source


Oderji H.Y.,Dalian University of Technology | Oderji H.Y.,University of Tehran | Behnejad H.,University of Tehran | Ferrando R.,DellUniversity Genoa | Ding H.,Dalian University of Technology
RSC Advances | Year: 2013

Anti-Mackay icosahedral clusters of composition Ag32M 13, where M is either Cu, Ni, or Co, have been recently shown to possess special structural stability both by calculations and experiments. These nanoalloys assume a core-shell arrangement, with an icosahedral core of 13 M atoms surrounded by an Ag shell of anti-Mackay structure. In this paper we study the melting of these three nanoalloys, showing that, despite the close similarity of the structures, melting takes place through quite different mechanisms. In particular, we find that Ag32Co13 and Ag32Ni13 present a premelting phenomenon which involves only the shell of the cluster while the core melts at higher temperatures, in agreement with previous calculations. On the contrary, in Ag32Cu 13, melting occurs through stages that involve the shell and the core at the same time. These findings are rationalized in terms of the different features of the energy landscape of these nanoalloys. Our simulations, in which special care has been devoted to avoid non-ergodicity problems, show also that the particles keep their core-shell structures even in the liquid phase, indicating an incomplete miscibility of Ag with Ni, Co or Cu at the nanoscale up to quite high temperatures. This journal is © The Royal Society of Chemistry 2013. Source


Bruno D.,DellUniversity Genoa
Journal of Mathematical Physics | Year: 2011

The paper is devoted to prove the existence of a local solution of the Hamilton-Jacobi equation in field theory, whence the general solution of the field equations can be obtained. The solution is adapted to the choice of the submanifold where the initial data of the field equations are assigned. Finally, a technique to obtain the general solution of the field equations, starting from the given initial manifold, is deduced. © 2011 American Institute of Physics. Source


Marian D.,Autonomous University of Barcelona | Marian D.,DellUniversity Genoa | Colomes E.,Autonomous University of Barcelona | Zanghi N.,DellUniversity Genoa | Oriols X.,Autonomous University of Barcelona
Journal of Physics: Conference Series | Year: 2015

The interest on weak measurements is rapidly growing during the last years as a unique tool to better understand and predict new quantum phenomena. Up to now many theoretical and experimental weak-measurement techniques deal with (relativistic) photons or cold atoms, but there is much less investigation on (non-relativistic) electrons in up-to-date electronics technologies. We propose a way to perform weak measurements in nanoelectronic devices through the measurement of the total current (particle plus displacement component) in such devices. We study the interaction between an electron in the active region of a electron device with a metal surface working as a sensing electrode by means of the (Bohmian) conditional wave function. We perform numerical (Monte Carlo) simulations to reconstruct the Bohmian trajectories in the iconic double slit experiment. This work opens new paths for understanding the quantum properties of an electronic system as well as for exploring new quantum engineering applications in solid state physics. Source

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