Search results for " MODELLI E METODI MATEMATICI"
showing 10 items of 263 documents
B-physics computations from Nf=2 tmQCD
2013
We present an accurate lattice QCD computation of the b-quark mass, the B and Bs decay constants, the B-mixing bag-parameters for the full four-fermion operator basis, as well as estimates for \xi and f_{Bq}\sqrt{B_q} extrapolated to the continuum limit and the physical pion mass. We have used Nf = 2 dynamical quark gauge configurations at four values of the lattice spacing generated by ETMC. Extrapolation in the heavy quark mass from the charm to the bottom quark region has been carried out using ratios of physical quantities computed at nearby quark masses, having an exactly known infinite mass limit.
Field- and irradiation-induced phenomena in memristive nanomaterials
2016
The breakthrough in electronics and information technology is anticipated by the development of emerging memory and logic devices, artificial neural networks and brain-inspired systems on the basis of memristive nano-materials represented, in a particular case, by a simple 'metal-insulator-metal' (MIM) thin-film structure. The present article is focused on the comparative analysis of MIM devices based on oxides with dominating ionic (ZrOx, HfOx) and covalent (SiOx, GeOx) bonding of various composition and geometry deposited by magnetron sputtering. The studied memristive devices demonstrate reproducible change in their resistance (resistive switching - RS) originated from the formation and …
Electron Angular Distribution in Laser-Assisted X-ray Photoeffect
1981
Calculations are reported of the differential cross section of the laser-assisted X-ray photoeffect from K shells showing that drastic changes occur in the shape of the ejected-electron angular distribution when laser photons are exchanged during the ionisation. This process appears well suited to the study of laser effects and multiphoton exchanges in laser-assisted atomic collisions.
Simple scheme for extracting work with a single bath
2019
We propose a simple protocol exploiting the thermalization of a storage bipartite system S to extract work from a resource system R. The protocol is based on a recent work definition involving only a single bath. A general description of the protocol is provided without specifying the characteristics of S. We quantify both the extracted work and the ideal efficiency of the process, also giving maximum bounds for them. Then, we apply the protocol to two cases: two interacting qubits and the Rabi model. In both cases, for very strong couplings, an extraction of work comparable with the bare energies of the subsystems of S is obtained and its peak is reached for finite values of the bath tempe…
Development of a predictive model for the shelf-life of Atlantic mackerel (Scomber scombrus)
2022
Despite its commercial value, the shelf-life of the Atlantic mackerel (Scomber scombrus) during refrigerated storage was poorly investigated. In this regard, the Quality Index Method (QIM) was proposed as a suitable scoring system for freshness and quality sensorial estimation of fishery products. This study aims to develop a deterministic mathematical model based on dynamic temperatures conditions and a suc-cessive statistical analysis of the results obtained. This model will be exploited to predict the shelf-life of the Atlantic mackerel based on specific storage temperatures. A total of 60 fresh fishes were subdivided into two groups and respectively stored in ice for 12 days at a consta…
A Simple Noise Model with Memory for Biological Systems
2005
A noise source model, consisting of a pulse sequence at random times with memory, is presented. By varying the memory we can obtain variable randomness of the stochastic process. The delay time between pulses, i. e. the noise memory, produces different kinds of correlated noise ranging from white noise, without delay, to quasi-periodical process, with delay close to the average period of the pulses. The spectral density is calculated. This type of noise could be useful to describe physical and biological systems where some delay is present. In particular it could be useful in population dynamics. A simple dynamical model for epidemiological infection with this noise source is presented. We …
Josephson-junction-based axion detection through resonant activation
2022
We discuss the resonant activation phenomenon on a Josephson junction due to the coupling of the Josephson system with axions. We show how such an effect can be exploited for axion detection. A nonmonotonic behavior, with a minimum, of the mean switching time from the superconducting to the resistive state versus the ratio of the axion energy and the Josephson plasma energy is found. We demonstrate how variations in switching times make it possible to detect the presence of the axion field. An experimental protocol for observing axions through their coupling with a Josephson system is proposed.
Generation of travelling sine-Gordon breathers in noisy long Josephson junctions
2022
The generation of travelling sine-Gordon breathers is achieved through the nonlinear supratransmission effect in a magnetically driven long Josephson junction, in the presence of losses, a current bias, and a thermal noise source. We demonstrate how to exclusively induce breather modes by means of controlled magnetic pulses. A nonmonotonic behavior of the breather-only generation probability is observed as a function of the noise intensity. An experimental protocol providing evidence of the Josephson breather's existence is proposed.
Monopoles and dualities in 3d N=2 quivers
2021
Seiberg-like dualities in 2+1d quiver gauge theories with 4 supercharges are investigated. We consider quivers made of various combinations of classical gauge groups U(N), Sp(N), SO(N) and SU(N). Our main focus is the mapping of the supersymmetric monopole operators across the dual theories. There is a simple general rule that encodes the mapping of the monopoles upon dualizing a single node. This rule dictates the mapping of all the monopoles which are not dressed by baryonic operators. We also study more general situations involving baryons and baryon-monopoles, focussing on three examples: SU−Sp, SO−SO and SO−Sp quivers.
Two-qubit quantum correlations versus single-qubit population
2009
It is considered a system made by two noninteracting qubits, initially entangled, embedded in zero-temperature bosonic independent environments. It is shown that different forms of quantum correlations for two qubits can be expressed in terms of excited state population of each single qubit. These relations are explicitly given for both entanglement and Bell function. This permits to evidence regions where there is entanglement without violation of a Bell inequality, then showing that entanglement does not necessarily witness the presence of quantum correlations nonreproducible by a classical local model, as identified by Bell inequality violations. We finally report the explicit time depen…