204 research outputs found
Exact results for the low energy AdS 4 × 3 string theory
No full textWe derive the Thermodynamic Bethe Ansatz equations for the relativistic sigma model describing the AdS4 × CP3 string II A theory at strong coupling (i.e. in the Alday-Maldacena decoupling limit). The corresponding Y-system involves an infinite number of Y functions and is of a new type, although it shares a peculiar feature with the Y-system for AdS4 × CP3. A truncation of the equations at level p and a further generalisation to generic rank N allow us an alternative description of the theory as the N = 4, p = ∞ representative in an infinite family of models corresponding to the conformal cosets (CPN-1)p × U(1), perturbed by a relevant composite field φ(N,p) = φ[(CPN-1)p] × φ[U(1)] that couples the two independent conformal field theories. The calculation of the ultraviolet central charge confirms the conjecture by Basso and Rej and the conformal dimension of the perturbing operator, at every N and p, is obtained using the Y-system periodicity. The conformal dimension of φ[(CPN-1)p] matches that of the field identified by Fendley while discussing integrability issues for the purely bosonic CPN-1 sigma model
Deforming the ODE/IM correspondence with
No full textThe ODE/IM correspondence is an exact link between classical and quantum
integrable models. The primary purpose of this work is to show that it remains
valid after perturbation on both sides of the
correspondence. In particular, we prove that the deformed Lax pair of the
sinh-Gordon model, obtained from the unperturbed one through a dynamical change
of coordinates, leads to the same Burgers-type equation governing the quantum
spectral flow induced by . Our main conclusions
have general validity, as the analysis may be easily adapted to all the known
ODE/IM examples involving integrable quantum field theories.Comment: 27 pages, 4 figure
Impiego della sintesi in situ di zeoliti da fly ash per il recupero di suoli contaminati da metalli pesanti e da xenobiotici organici: studi preliminari
No full textA numerical procedure to estimate seismic fragility of cylindrical ground-supported steel silos containing granular-like material
No full textThe paper presents a study on the evaluation of seismic fragility of cylindrical ground-supported steel silos intended for storing solid material. Silos are a key facility in industrial processes. For example, cylindrical steel silos constitute the main structural component for several industrial activities, such as the ones aimed at the production of food and beverage, and seismic actions can cause high economic losses and long functionality interruptions. Thus, the main goal of this paper is to propose a numerical procedure aimed to assess the seismic fragility of different cylindrical steel silos, accounting for varying geometries and service conditions (i.e., filling level of granular-like material), and observing different failure modes. In detail, a set of smooth steel silos was selected, considering different geometrical configurations (i.e., varying from squattest to slenderest structures). Different service conditions were simulated, with the aim to observe the behaviour of empty and filled silos (30%, 60%, and 90% of filling degree with respect to the maximum capacity). For each configuration, a detailed numerical model was developed under proper boundary conditions, adequately simulating the shell structure, the solid material inside, and the interactions between them. After validating the numerical models against existing literature data, three different failure modes were identified and assessed, accounting for the most recurrent post-elastic buckling type (i.e., elephant foot) and considering the possible occurrence of the elastic ones (i.e., diamond or similar shape failures at the middle and top of the structures). Both static and dynamic analyses were performed to identify the most probable failure modes and evaluate the probability of exceeding each one. As the output of the proposed approach, the seismic performance of each silo under a specific limit state was provided in the form of fragility curves. The results highlight some novel aspects, starting from the role that service conditions assume in the silos seismic performance up to the possible differences in terms of failure modes for different silos geometrical structural configurations
Zeolite synthesis from pre-treated coal fly ash in presence of soil as a tool for soil remediation
No full textZeolite synthesis in soils amended with coal fly ash: evaluation of their role in the stabilization of heavy metals in polluted soils
No full textCharacterisation of different coal fly ash for their application in the synthesis of Zeolite X as cation exchanger for soil remediation
No full textRegge trajectories and bridges between them in integrable AdS/CFT
No full textWe study the analytic continuation in the spin of the planar spectrum of ABJM theory using the integrability-based Quantum Spectral Curve (QSC) method. Under some minimal assumptions, we classify the analytic properties of the Q-functions appearing in the QSC compatible with the spin being non-integer. In this way, we find not one but two distinct possibilities. While one is related to standard Regge trajectories, we show that the second choice can be used to build bridges which connect leading and subleading Regge trajectories, thus giving a shortcut to reach infinitely many sheets of the spin Riemann surface without going explicitly around the branch points in the complex spin plane. Moreover, the bridges are exact spin reflections of standard Regge trajectories. Together, these results reveal the existence of a hidden symmetry which we call “twist/co-twist symmetry”: every non-BPS local operator has an exact image — living below unitarity on a different Regge trajectory — with the same ∆ and the spin flipped by a Weyl reflection. We discuss how an analogous phenomenon, based on the same mechanism at the level of the QSC, also occurs at non-perturbative level in N =4 SYM. This provides a framework to understand recent independent observations of the symmetry in this model at weak and strong coupling. We present numerical results for Regge trajectories in planar ABJM theory, in particular we compute exactly the coupling dependence of the position of the leading Regge pole in the correlator of four stress tensors. The shape of this leading trajectory shows a behaviour at weak coupling that strongly resembles the BFKL limit in N =4 SYM
Spectral equivalences, Bethe ansatz equations, and reality properties in PT-symmetric quantum mechanics
No full textThe one-dimensional Schrodinger equation for the potential x(6)+alphax(2)+l (l+1)/x(2) has many interesting properties. For certain values of the parameters I and a the equation is in turn supersymmetric (Witten) and quasi-exactly solvable (Turbiner), and it also appears in Lipatov's approach to high-energy QCD. In this paper we signal some further curious features of these theories, namely novel spectral equivalences with particular second- and third-order differential equations. These relationships are obtained via a recently observed connection between the theories of ordinary differential equations and integrable models. Generalized supersymmetry transformations acting at the quasi-exactly solvable points are also pointed out, and an efficient numerical procedure for the study of these and related problems is described. Finally we generalize slightly and then prove a conjecture due to Bessis, Zinn-Justin, Bender and Boettcher, concerning the reality of the spectra of certain PT-symmetric quantum mechanical systems
Zeolite synthesis from pre-treated coal fly ash in presence of soil clay minerals and humic substances as a tool for soil remediation
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