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On the canonical equivalence between Jordan and Einstein frames
No full textA longstanding issue is the classical equivalence between the Jordan and the Einstein frames, which is considered just a field redefinition of the metric tensor and the scalar field. In this work, based on the previous result that the Hamiltonian transformations from the Jordan to the Einstein frame are not canonical on the extended phase space, we study the possibility of the existence of canonical transformations. We show that on the reduced phase space – defined by suitable gauge fixing of the lapse and shifts functions – these transformations are Hamiltonian canonical. Poisson brackets are replaced by Dirac's brackets following the Bergman-Dirac's procedure. The Hamiltonian canonical transformations map solutions of the equations of motion in the Jordan frame into solutions of the equations of motion in the Einstein frame
Linear response theory for spin alignment of vector mesons in thermal media
No full textWe present a calculation of the spin alignment for unflavored vector mesons in thermalized quark-gluon plasma based on the Kubo formula in linear response theory. This is achieved by expanding the system to the first order of the coupling constant and the spatial gradient. The effect strongly relies on the vector meson's spectral functions which are determined by the interaction and medium properties. The spectral functions are calculated for the one-quark-loop self-energy with meson-quark interaction. The numerical results show that the correction to the spin alignment from the thermal shear tensor is of the order 10-4∼10-5 for the chosen values of quark-meson coupling constant, if the magnitude of thermal shear tensor is 10-2
Accessibilità delle Web APP della DSI
Get PDF<p>Rendere un’applicazione web accessibile, oltre ad essere un dovere sociale, permette ad ogni utente di poter usufruire delle sue funzionalità in un modo più profittevole.</p>\n\n<p>Gli aspetti caratterizzanti l’accessibilità si dividono in due categorie principali: visibili e invisibili.</p>\n\n<p>I primi sono degli aspetti di cui l’utente ha un’esperienza diretta e sono ad esempio i colori utilizzati e il modo in cui sono realizzati gli elementi interattivi della pagina.</p>\n\n<p>I secondi, invece, corrispondono al modo in cui le pagine web sono codificate e possono essere analizzate da un lettore automatico.</p>\n\n<p>In questa trattazione saranno discusse entrambe le tipologie di aspetti e il focus sarà puntato sulla loro gestione nell’ambito dello sviluppo interno alla DSI, che ha tra i propri obiettivi la realizzazione di applicativi web a supporto delle attività amministrative dell’INFN.</p>
Observation of microscopic confinement dynamics by a tunable topological θ-angle
No full textThe topological θ-angle is central to several gauge theories in condensed-matter and high-energy physics. For example, it is responsible for the strong CP problem in quantum chromodynamics and can emerge in effective theories of electrodynamics in topological insulators. Although analogue quantum simulators potentially offer a venue for realizing and controlling the θ-angle, doing so has hitherto remained an outstanding challenge. Here, we describe the experimental realization of a tunable topological θ-angle in a Bose–Hubbard gauge-theory quantum simulator, which was implemented through a tilted superlattice potential that induces an effective background electric field. We demonstrate the emerging physics through the direct observation of the confinement–deconfinement transition of (1 + 1)-dimensional quantum electrodynamics. Using an atomic-precision quantum gas microscope, we distinguish between the confined and deconfined phases by monitoring the real-time evolution of particle–antiparticle pairs. Our work provides a step forward in the realization of topological terms on modern quantum simulators
Anomalies and persistent order in the chiral Gross-Neveu model
No full textWe study the 2d chiral Gross-Neveu model at finite temperature T and chemical potential μ. The analysis is performed by relating the theory to a SU(N) × U(1) Wess-Zumino-Witten model with appropriate levels and global identifications necessary to keep track of the fermion spin structures. At μ = 0 we show that a certain ℤ-valued 't Hooft anomaly forbids the system to be trivially gapped when fermions are periodic along the thermal circle for any N and any T > 0. We also study the two-point function of a certain composite fermion operator which allows us to determine the remnants for T > 0 of the inhomogeneous chiral phase configuration found at T = 0 for any N and any μ. The inhomogeneous configuration decays exponentially at large distances for anti-periodic fermions while it persists for T > 0 and any μ for periodic fermions, as expected from anomaly considerations. A large N analysis confirms the above findings
G-structures for black hole near-horizon geometries
No full textWe derive necessary and sufficient conditions for warped AdS solutions of Type II supergravity to preserve = 1 supersymmetry, in terms of bispinors. Such solutions generically support an SU(3)-structure on their internal manifold M, which can experience an enhancement to a G-structure. We perform an SU(3)-structure torsion classes analysis and express the fluxes and other physical fields in terms of these, in general. We use our results to derive two new classes of AdS solutions. In (massive) Type IIA supergravity we derive an = 1 supersymmetric class for which M decomposes as a weak G-manifold foliated over an interval and which is locally defined in terms of a degree three polynomial. In Type IIB supergravity we find a class of AdS × S × CY × Σ solutions preserving small = 4 supersymmetry, governed by a harmonic function on Σ and partial differential equations reminiscent of D3-D7-brane configurations
A fourth-order accurate finite volume scheme for resistive relativistic MHD
Get PDF<p>We present a finite-volume, genuinely fourth-order accurate numerical method for solving the equations of resistive relativistic magnetohydrodynamics in Cartesian coordinates. In our formulation, the magnetic field is evolved in time in terms of face-average values via the constrained-transport method, while the remaining variables (density, momentum, energy, and electric fields) are advanced as cell volume averages. Spatial accuracy employs fifth-order accurate WENO-Z reconstruction from point values (as described in a companion paper) to obtain left and right states at zone interfaces. Explicit flux evaluation is carried out by solving a Riemann problem at cell interfaces, using the Maxwell-Harten-Lax-van Leer with contact wave resolution. Time-stepping is based on the implicit-explicit Runge-Kutta (RK) methods, of which we consider both the third-order strong stability preserving SSP3(4,3,3) and a recent fourth-order additive RK scheme, to cope with the stiffness introduced by the source term in Ampere's law. Numerical benchmarks are presented in order to assess the accuracy and robustness of our implementation.</p>
Carta della Natura del comune di Campobasso: Carta degli habitat alla scala 1:5.000
No full text<p>Layout di stampa della Carta della Natura del comune di Campobasso alla scala 1:5.000. Habitat codificati secondo il sistema di classificazione EUNIS (https://eunis.eea.europa.eu/habitats.jsp).</p>\n\n<p>La Carta della Natura alla scala 1:5.000 del comune di Campobasso è il frutto di un accordo di ricerca fra l’Università degli Studi del Molise e l’ISPRA nell’ambito del “Progetto PNNR National Biodiversity Future Centre - Spoke 5: Urban Biodiversity”, con l’obiettivo generale di produrre, all’interno della Functional Urban Area (FUA) di Campobasso, una base conoscitiva omogenea con dati cartografici e valutativi sugli habitat, raccogliendo in un Sistema Informativo dati utili a individuare le aree di maggior valore ecologico e quelle più a rischio di degrado da un punto di vista naturalistico-ambientale.</p>\n\n<p>Come primo prodotto della collaborazione è stata realizzata la Carta degli habitat a scala locale del comune di Campobasso. La carta costituisce un supporto alle attività di pianificazione e di monitoraggio della biodiversità nel contesto dell'aree urbana di Campobasso e potrà essere utilizzata ad esempio come base conoscitiva in progetti di riforestazione urbana o per la realizzazione di piani e progetti relativi alla rete di infrastrutture verdi.</p>
Dataset related to article \"Telerehabilitation for Stroke: A Personalized Multi-Domain Approach in a Pilot Study\
No full text<p>Dataset description available on the downloadable file.</p>
The present and future of QCD
No full textThis White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research