arXiv subjects

Rosa Di Salvo

Publications and source records attributed to Rosa Di Salvo.

4 recordsLinked to original sources

arXiv2021

Generalized Hamiltonian for a two-mode fermionic model and asymptotic equilibria

In some recent papers, the so called $(H,ρ)$-induced dynamics of a system $\mathcal{S}$ whose time evolution is deduced adopting an operatorial approach, has been introduced. According to the formal mathematical apparatus of quantum mechanics, $H$ denotes the Hamiltonian for $\mathcal{S}$, while $ρ$ is a certain rule applied periodically on $\mathcal{S}$. In this approach the rule acts at specific times $kτ$, with $k$ integer and $τ$ fixed, by modifying some of the parameters entering $H$ according to the state variation of the system. As a result, a dynamics admitting an asymptotic equilibrium state can be obtained. Here, we consider the limit for $τ\rightarrow 0$, so that we introduce a generalized model leading to asymptotic equilibria. Moreover, in the case of a two-mode fermionic model, we are able to derive a relation linking the parameters involved in the Hamiltonian to the asymptotic equilibrium states.

math-ph↗

arXiv2021

$(H,ρ)$--induced political dynamics: facets of the disloyal attitudes into the public opinion

A simple model, suitable to describe the dynamics of a political system consisting of three macro--groups affected by turncoat--like behaviors and the influence of the opportunistic attitudes of politicians on voters' opinion, is presented. The model is based on raising and lowering fermionic operators whose dynamics is ruled by a suitable quadratic Hamiltonian operator with the addition of specific rules (depending on the variations of the mean values of the observables) able to adjust periodically the model to the political environment, \emph{i.e.}, we move in the framework of the so called $(H,ρ)$--induced dynamics approach.

physics.soc-ph↗

arXiv2021

Political dynamics affected by turncoats

An operatorial theoretical model based on raising and lowering fermionic operators for the description of the dynamics of a political system consisting of macro--groups affected by turncoat--like behaviors is presented. The analysis of the party system dynamics is carried on by combining the action of a suitable quadratic Hamiltonian operator with specific rules (depending on the variations of the mean values of the observables) able to adjust periodically the conservative model to the political environment.

physics.soc-ph↗

arXiv2021

A Consistent Approach to Approximate Lie Symmetries of Differential Equations

Lie theory of continuous transformations provides a unified and powerful approach for handling differential equations. Unfortunately, any small perturbation of an equation usually destroys some important symmetries, and this reduces the applicability of Lie group methods to differential equations arising in concrete applications. On the other hand, differential equations containing \emph{small terms} are commonly and successfully investigated by means of perturbative techniques. Therefore, it is desirable to combine Lie group methods with perturbation analysis, \emph{i.e.}, to establish an approximate symmetry theory. There are two widely used approaches to approximate symmetries: the one proposed in 1988 by Baikov, Gazizov and Ibragimov, and the one introduced in 1989 by Fushchich and Shtelen. Moreover, some variations of the Fushchich--Shtelen method have been proposed with the aim of reducing the length of computations. Here, we propose a new approach that is consistent with perturbation theory and allows to extend all the relevant features of Lie group analysis to an approximate context. Some applications are also presented.

math-ph↗