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G. Modanese

Publications and source records attributed to G. Modanese.

At least 19 recordsLinked to original sources
arXiv2026

Coherent Oscillations of Protons in Hydrogen-loaded Metals

We review recent calculations and numerical simulations showing the formation of coherent states of protons in hydrogen-loaded metals with a cubic crystal lattice. In these states protons oscillate coherently at frequencies of the order of $10^{13}\,\mathrm{Hz}$ and in a fixed phase relation with a strong high-frequency electric field which is trapped in the material, especially if the material is made of micro-powders. The energy gap of the coherent ground state is estimated to be well above thermal energies, of the order of a fraction of an eV per particle, and therefore large enough to make the state robust against thermal fluctuations. The analytical calculations address the realistic case of a large number of protons, in the rotating-wave approximation. The numerical calculations are presently limited to a small number of protons but go beyond the rotating-wave approximation and allow one to take into account a dissipation term associated with the strong oscillating electric field. The next task of this theoretical model is to compute the excited states of the coherent system. There are strong indications that in those states protons can be excited by an external pump to energies much larger than those achievable by single incoherent protons in condensed matter. Such energies are large enough to make possible some electron-capture processes, with generation of slow neutrons. This dynamical mechanism offers an alternative to the Widom--Larsen hypothesis of ``heavy electrons'', and is closer to current models in mainstream physics. The consequences, in terms of nuclear transmutations, of neutron generation via electron capture would be similar to those predicted by Widom and Larsen, plus several other processes like those recently re-examined by Metzler et al.

physics.gen-ph↗
arXiv2026

Statistics of non-conserved observables in Lindblad master equations

We study the dynamics of observables that are conserved under the Hamiltonian evolution of a closed quantum system, but cease to be conserved when the system is coupled to a Markovian environment and described by a Lindblad master equation. Starting from the adjoint Lindblad equation, we derive elementary expressions for the time derivatives of the expectation value and second moment of an observable $O$, with particular emphasis on the case $[H,O]=0$ but $\mathcal L^\dagger(O)\neq 0$. These formulae provide a direct assessment of how collapse operators break Hamiltonian conservation laws and generate fluctuations of formerly conserved quantities. The discussion is illustrated by analytic examples: one-qubit amplitude damping, a two-qubit excitation-number model, a momentum-diffusion model in which the mean is conserved while the variance grows, and the Jaynes-Cummings model. The latter also shows the complementary case of a reservoir coupled through a conserved quantity, where dephasing can occur without changing the statistics of that quantity. We finally comment on the relation between Lindblad source terms and idealized wave-function reduction models in which local conservation may hold only statistically.

physics.gen-ph↗
arXiv2026

Beyond minimal coupling for charged scalars? Modified electrodynamics and London-penetration tests

We discuss an effective modification of the electromagnetic coupling for charged scalar condensates. The motivation is not an inconsistency of standard scalar QED, but a semiclassical tension: for scalar fields the term linear in $A_\mu$ is not itself the conserved source current of the interacting theory, while for Dirac fields the usual interaction already has the form $-A_\mu J^\mu$ with an $A_\mu$-independent conserved current. We review this distinction, clarify the effective-theory status of the alternative coupling, and state explicitly the corresponding limitations: the framework is not proposed as a UV-complete replacement of gauge theory and standard Ward identities or scattering-theory results should not be expected to survive unchanged. We then focus on the condensed-matter consequence relevant to superconductors. For bosonic charged condensates the modified framework predicts a rescaled magnetic penetration depth, $\lambda_{\rm mag}=\lambda_L/\sqrt{2}$, while leaving the qualitative structure of AC electrodynamics and the type-I/type-II classification unchanged up to parameter mapping. Finally, we compare literature values of an ``optical'' penetration depth $\lambda_{\rm opt}$, inferred from optical/THz superfluid spectral weight, with independently determined magnetic lengths $\lambda_{\rm mag}$ for Nb, Pb, YBCO, MgB$_2$ and Ba(Fe,Co)$_2$As$_2$. The present data do not constitute a proof of the modified coupling, because sample, doping and disorder systematics remain important; nevertheless, Nb, optimally doped YBCO and Ba(Fe,Co)$_2$As$_2$ show the suggestive trend $\lambda_{\rm opt}>\lambda_{\rm mag}$, whereas MgB$_2$ is consistent with the standard result $\lambda_{\rm opt}\simeq\lambda_{\rm mag}$ and Pb is not a clean test because of strong nonlocal corrections.

physics.gen-ph↗
arXiv2026

A Structural Link Between the Bohm Quantum Potential and the Scalar Mode of Aharonov-Bohm Electrodynamics in a Bosonic Schr\"odinger Model

We discuss a formal and physical connection between the Bohm quantum potential and the scalar mode of the Aharonov-Bohm extension of electrodynamics. The analysis is motivated by the effective non-relativistic bosonic model recently proposed by Minotti and Modanese, in which the electromagnetic field is coupled to a conserved current while the field equations contain an additional source term. In the Madelung representation $\psi=R\exp(i\theta/\hbar)$, the Bohm quantum potential $ Q_B=-\frac{\hbar^2}{2m}\frac{\nabla^2 R}{R} $ is determined by the relative curvature $\nabla^2R/R$ of the amplitude profile $R$. In the same bosonic model, the scalar electromagnetic mode $S=\partial_\mu A^\mu$ is sourced by the extra-current $I=\partial_\mu j^\mu$, which contains the density-weighted electromagnetic combination $\nabla\cdot(R^2\mathbf A)$. Thus $Q_B$ does not act as a direct source of $S$; rather, the two quantities probe different differential aspects of the same amplitude profile: $Q_B$ is sensitive to the relative curvature of $R$, whereas the source of $S$ is sensitive to its density and gradient content through $R^2$ and $\nabla R$. We show that, once boundary and normalization data are fixed, this observation may be written as a mediated functional dependence of $S$ on $Q_B$ through $R$. We also clarify the physical status of $Q_B$: although it is state-dependent and should not be interpreted as an autonomous external potential, its density-weighted integral gives the amplitude-gradient energy, equivalently a Fisher-information contribution. This makes $Q_B$ a compact diagnostic of quantum pressure, rigidity, and inhomogeneity of a bosonic condensate. The resulting link with $S$ is therefore best understood as a structural relation between the order-parameter amplitude profile of the condensate and the scalar sector of the extended electromagnetic theory.

physics.gen-ph↗
arXiv2026

Quantum collapse, local conservation of charge, and possible experimental consequences

We investigate the possibility that idealized quantum state-reduction processes may produce a local violation of charge conservation. If this occurs, the corresponding electromagnetic fields cannot be consistently described within Maxwell electrodynamics, and a natural alternative is provided by Aharonov-Bohm electrodynamics, which reduces to Maxwell theory when local charge conservation holds, but remains compatible with non-conserved sources. Within this framework we first analyze how state reduction may generate non-conserved local currents, including statistically compensated cases and biased tunnelling configurations with persistent average current. We then study the interaction of gauge waves with fermionic and bosonic quantum systems, the latter being described by a modified Schr\"odinger equation previously proposed for boson matter. As an application, we discuss the interaction of gauge waves with superconductors and show that they can effectively shield such waves. Finally, we present experimental proposals based on inverse-biased diodes and estimate the expected detector response.

physics.gen-ph↗
arXiv2026

Effective Observer-Split Source Terms in Rotating Frames and Gravitomagnetic Backgrounds in Extended Aharonov-Bohm Electrodynamics

We examine whether the observer split of a covariantly conserved electric current in a rotating finite system can provide a physically constrained effective source for the scalar sector of extended Aharonov--Bohm electrodynamics. We first recall that rotation, a stationary gravitomagnetic background, or a change of coordinates cannot by themselves generate genuine microscopic charge non-conservation for standard locally $U(1)$-invariant matter; this simple no-go statement is used to delimit the phenomenological context. In a $3+1$ decomposition adapted to a rotating apparatus, the transport continuity equation contains the exact observer-split term $I_{\mathrm{split}}=N^{-1}D_i(\rho\beta^i)$, which reduces for weak rigid rotation to $I_G=\Omega\partial_\phi\rho$. We propose to use this restricted, congruence-dependent source as a phenomenological input to the extended scalar sector. The relevant observer/evolution structure is not an arbitrary coordinate choice: the laboratory synchronization and readout protocol select the foliation, while the rotor motion fixes the evolution field relative to it. We characterize which features of a genuine extra-current can and cannot be represented by this construction, and discuss falsifiable signatures, including rotation reversal, axisymmetric-source suppression, gradient scaling, and a recently proposed optically gated rotating-disc test. Analogue-gravity systems are also identified as a possible future setting in which a preferred material flow naturally selects the observer congruence.

physics.gen-ph↗
arXiv2026

Fluctuations in Aharonov-Bohm Electrodynamics

We consider the application of the Fluctuation Dissipation Theorem (FDT) to the electrodynamics of Aharonov-Bohm (ABE), which differs from Maxwell's in that it allows for local non-conservation of charge. For the case of a system of non-conserved charges at thermal equilibrium we obtain the same spectral distribution of energy of the electromagnetic field as in Maxwell electrodynamics. However, the electric field contribution to that energy doubles that in Maxwell case, while the magnetic contribution is the same as in Maxwell theory, the electric excess energy is compensated by a negative contribution arising form the Aharonov-Bohm (AB) scalar field. For a conductor with local non-conservation of charge described by the $\gamma$ model, we derive the spectrum of current correlation at first order in $\gamma$, which results in a violet noise contribution added to the classical Johnson-Nyquist white noise result for the voltage fluctuations in a conductor.

physics.gen-ph↗
arXiv2026

Scalar-tensor gravity and Aharonov-Bohm electrodynamics with bosons: applications to superconductors

We study a scalar-tensor extension of gravity with two scalar fields coupled to the Aharonov-Bohm extension of electrodynamics, where the scalar mode $S\equiv\partial_\mu A^\mu$ is dynamical. In this framework the trace of the electromagnetic energy-momentum tensor is nonvanishing and the scalar $S$ induces an electro-gravitational coupling that can be enhanced by the vacuum expectation value of the second gravitational scalar. For bosonic matter described by a macroscopic wavefunction (as in superconductors), the coupling to the electromagnetic potential generates $S$ already at the semiclassical level, implying sizable junction-induced discontinuities. Including the scalar-tensor sector yields a nonlinear system for $S$ and a gravitational scalar combination $\beta$ that admits a bulk saturation solution $S_{\rm sat}^2=(\Lambda\lambda_L^2)^{-1}$ and a corresponding threshold condition for macroscopic effects. We apply these results to pulsed discharges across normal-superconducting junctions and obtain scaling relations for the onset of anomalous gravitational signals in terms of current density, pulse duration, and superconducting volume, consistent with reported threshold behavior in two independent experimental configurations for a single microscopic parameter. We also present time-dependent propagating solutions in the weak-field regime and derive a class of one-dimensional traveling exact solutions of the nonlinear vacuum Einstein equations.

physics.gen-ph↗
arXiv2025

Generalized local charge conservation in many-body quantum mechanics

In the framework of the quantum theory of many-particle systems, we study the compatibility of approximated Non-Equilibrium Green Functions (NEGFs) and of approximated solutions of the Dyson equation with a modified continuity equation of the form $\partial_t \langle \rho \rangle+(1-\gamma)\nabla\cdot \langle\mathbf{J} \rangle=0$. A continuity equation of this kind allows the e.m.\ coupling of the system in the extended Aharonov-Bohm electrodynamics, but not in Maxwell electrodynamics. Focusing on the case of molecular junctions simulated numerically with the Density Functional Theory (DFT), we further discuss the re-definition of local current density proposed by Wang et al., which also turns out to be compatible with the extended Aharonov-Bohm electrodynamics.

physics.gen-ph↗
arXiv2025

Do we need an alternative to local gauge coupling to electromagnetic fields?

The local gauge coupling through the recipe $\partial_\mu \psi \to \partial_\mu \psi + iqA_\mu \psi$, that works so well with Dirac spinors in QED and in the gauge theories of the Standard Model, has a peculiarity when applied to scalar fields: it generates in the Lagrangian a coupling term $J_\mu A^\mu$ in which $J_\mu$ does not coincide with the conserved N\"other current associated to the global gauge symmetry. This is not an inconsistency, just a feature that appears when working out the locally gauge invariant action, and which ensures that the correct conserved current is the source of the gauge field. What would happen then if we were to assume for the scalar field the same coupling $J_\mu A^\mu$ through a conserved current which holds for spinor QED and classical electrodynamics? The consequence is that one is forced in that case to renounce to the principle of local gauge symmetry and must thus consider the electromagnetic (e.m.) field to be described by electrodynamic theories compatible with that lack of invariance, like the extended electrodynamics by Aharonov-Bohm. No differences with the usual theory appear for fermion systems when strict local charge conservation applies. In particular, if we consider the non-relativistic quantum theory as the low-energy limit of the relativistic theory, we would expect no modifications of Schr\"odinger equation when applied to fermion systems. However, when scalar boson systems are considered, like Cooper pairs quasi-particles in superconductors, in the new formulation the e.m.\ fields include a source, additional to the usual conserved four-current, and, besides, the corresponding Schr\"odinger equation acquires a new term, proportional to $\mathbf{A}^2$, which can lead to observable consequences, like ... (length limit reached, see PDF)

physics.gen-ph↗
arXiv2025

Excited states of coherent harmonic qubits with long-range photon coupling and dissipation

It is known that ensembles of interacting oscillators or qubits can exhibit the phenomenon of quantum synchronization. In this work we consider a set of $N$ identical two-state systems that we call ``harmonic qubits'', because the kinetic part of their Hamiltonian is of the form $\omega_0 \sum_i a^\dagger_i a_i$, coupled through a multi-state ``photon'' mode subject to dissipation. It has been proven numerically that when the coupling between the qubits and the photon is sufficiently strong, the ensemble condenses into a ground state with negative energy, the energy gap is proportional to $N$ and there are clear cross correlations $\langle a^\dagger_i a_j \rangle$. Here we are interested into the energy spectrum of the excited states of this system. In order to obtain information on the coherent transitions we introduce a weak coupling of each qubit with an external oscillator of variable frequency $\omega$ and we check via Monte Carlo time evolution for which values of $\omega$ variations in the occupation of the external oscillator occur. After adding a second external oscillator coupled to the first only through the $N$ qubits, we also look at the energy transfer between the two external oscillators in dependence on their frequency, a transfer which is possible only through the excited states of the qubits. Above threshold (when $E_0<0$) we find resonant transfer at frequencies which are definitely higher, and growing with $N$. This signals the presence of collective excited states, separated by large energy gaps, which are absent below threshold.

physics.gen-ph↗
arXiv2024

A new theory of tensor-scalar gravity coupled to Aharonov-Bohm electrodynamics

Tensor-scalar theories of gravitation are commonly employed as extensions of General Relativity that allow to describe a much wider phenomenology. They are also naturally generated as low energy limit of higher-dimensional or unified theories, and the gravitational scalar components can represent quantum corrections to the Einstein theory. The coupling of the scalars to an e.m. field does not introduce any relevant new physics if the e.m. action has the usual Maxwell form, implying a vanishing trace of the e.m. energy-momentum tensor. In the case of the extended Aharonov-Bohm electrodynamics some interesting new situations are possible, which in this work are analyzed in the gravitational weak-field approximation and for a basic version of tensor-scalar gravity involving only a Brans-Dicke field plus another scalar. Since the Aharonov-Bohm theory differs from Maxwell theory only in the presence of anomalous sources with local violation of charge conservation, which is thought to be possible only at a quantum level, the resulting formal framework can be useful to model interactions between gravitation and physical systems with macroscopic quantization. The theory contains some unknown parameters, the most important being the VEV $\psi_0$ of the second gravitational scalar and the level $\gamma$ of violation of local charge conservation in the e.m. sector. An attempt is done to relate these parameters to some experimental constraints. However, there is presently much space left for uncertainty.

physics.gen-ph↗
arXiv2024

Diffusion on assortative networks: from mean-field to agent-based, via Newman rewiring

In mathematical models of epidemic diffusion on networks based upon systems of differential equations, it is convenient to use the Heterogeneous Mean Field approximation (HMF) because it allows to write one single equation for all nodes of a certain degree $k$, each one virtually present with a probability given by the degree distribution $P(k)$. The two-point correlations between nodes are defined by the matrix $P(h|k)$, which can typically be uncorrelated, assortative or disassortative. After a brief review of this approach and of the results obtained within this approximation for the Bass diffusion model, in this work we look at the transition from the HMF approximation to the description of diffusion through the dynamics of single nodes, first still with differential equations, and then with agent-based models. For this purpose, one needs a method for the explicit construction of ensembles of random networks or scale-free networks having a pre-defined degree distribution (Configuration Model) and a method for rewiring these networks towards some desired or "target" degree correlations (Newman Rewiring). We describe Python-NetworkX codes implemented for the two methods in our recent work and compare some of the results obtained in the HMF approximation with the new results obtained with statistical ensembles of real networks, including the case of signed networks.

physics.soc-ph↗
arXiv2024

Spectral Analysis of Proton Eigenfunctions in Crystalline Environments

The Schr\"odinger equation and Bloch theorem are applied to examine a system of protons confined within a periodic potential, accounting for deviations from ideal harmonic behavior due to real-world conditions like truncated and non-quadratic potentials, in both one-dimensional and three-dimensional scenarios. Numerical computation of the energy spectrum of bound eigenfunctions in both cases reveals intriguing structures, including bound states with degeneracy matching the site number $N_w$, reminiscent of a finite harmonic oscillator spectrum. In contrast to electronic energy bands, the proton system displays a greater number of possible bound states due to the significant mass of protons. Extending previous research, this study rigorously determines the constraints on energy gap and oscillation amplitude of the previously identified coherent states. The deviations in energy level spacing identified in the computed spectrum, leading to minor splitting of electromagnetic modes, are analyzed and found not to hinder the onset of coherence. Finally, a more precise value of the energy gap is determined for the proton coherent states, ensuring their stability against thermal decoherence up to the melting temperature of the hosting metal.

physics.gen-ph↗
arXiv2024

Simple circuit and experimental proposal for the detection of gauge-waves

Aharonov-Bohm electrodynamics predicts the existence of traveling waves of pure potentials, with zero electromagnetic fields, denoted as gauge waves, or g-waves for short. In general, these waves cannot be shielded by matter since their lack of electromagnetic fields prevents the material from reacting to them. However, a not-locally-conserved electric current present in the material does interact with the potentials in the wave, giving the possibility of its detection. In [F.M., G.M., Eur.Phys.J. C 83, 1086 (2023)] the basic theoretical description of a detecting circuit was presented, based on a phenomenological theory of materials that can sustain not-locally-conserved electric currents. In the present work we discuss how that circuit can be built in practice, and used for the effective detection of g-waves.

physics.class-ph↗
arXiv2024

The Bass diffusion model: agent-based implementation on arbitrary networks

We show how the combined use of the free software packages networkX and NetLogo allows to implement quickly and with large flexibility agent-based network simulations of the classical Bass diffusion model and of its extensions and modifications. In addition to the standard internal graph implementations available in NetLogo (random, Barabasi-Albert-1 and small world), one can thus employ more complex Barabasi-Albert and small-world networks, plus scale-free networks with arbitrary power-law exponent $\gamma$ built in networkX through a configuration model algorithm. It is also possible to induce degree correlations in the networks in a controlled way via Newman rewiring and to simulate dynamics on arbitrary signed networks (networks where link can have positive or negative weights, with corresponding effects on diffusion). Some new results obtained in the agent-based simulations (and differing from those in mean-field approximation) are the following. The introduction of assortative correlations in scale-free networks has the effect of delaying the adoption peak in the Bass model, compared to the uncorrelated case. The peak time $t_{max}$ depends strongly also on the maximum degree effectively present in the network. For diffusion models with threshold on signed network, if negative influences have a weight equal to or greater than positive influences, then a high level of clustering tends to cause adoption blockades. In connection to this, by analysing statistical ensembles of assortative scale-free networks generated via Newman rewiring one observes a remarkable strong correlation between the function of the average degree of first neighbors $\bar{k}_{nn}(k)$ and the average clustering coefficient depending on the degree $\bar{C}(k)$.

physics.gen-ph↗
arXiv2023

Gauge waves generation and detection in Aharonov-Bohm electrodynamics

The extended Aharonov-Bohm electrodynamics has a simple formal structure and allows to couple the e.m. field also to currents which are not locally conserved, like those resulting from certain non-local effective quantum models of condensed matter. As it often happens in physics and mathematics when one tries to extend the validity of some equations or operations, new perspectives emerge in comparison to Maxwell theory, and some ''exotic'' phenomena are predicted. For the Aharonov-Bohm theory the main new feature is that the potentials $A^\mu$ become univocally defined and can be measured with probes in which the ''extra-current'' $I=\partial_\mu j^\mu$ is not zero at some points. As a consequence, it is possible in principle to detect pure gauge-waves with $\mathbf{E}=\mathbf{B}=0$, which would be regarded as non-physical in the Maxwell gauge-invariant theory with local current conservation. We discuss in detail the theoretical aspects of this phenomenon and propose an experimental realization of the detectors. A full treatment of wave propagation in anomalous media with extra-currents and of energy-momentum balance issues is also given.

physics.gen-ph↗
arXiv2023

Generation of scale-free assortative networks via Newman rewiring for simulation of diffusion phenomena

By collecting and expanding several numerical recipes developed in previous work, we implement an object-oriented Python code, based on the networkX library, for the realization of the configuration model and Newman rewiring. The software can be applied to any kind of network and "target" correlations, but it is tested with focus on scale-free networks and assortative correlations. For generating the degree sequence we use the method of "random hubs", which gives networks with minimal fluctuations. For the assortative rewiring we use the simple Vazquez-Weigt matrix as a test in the case of random networks; since it appears to be not effective in the case of scale-free networks we then turn to another recipe which generates matrices with decreasing off-diagonal elements. The rewiring procedure is important also at the theoretical level, in order to test which types of statistically acceptable correlations can actually be realized in concrete networks. From the applicative point of view, its main use is in the construction of correlated networks for the solution of dynamical or diffusion processes by analyzing the evolution of single nodes, i.e., beyond the Heterogeneous Mean Field approximation. As an example, we report on an application to the Bass diffusion model, with calculations of the time $t_{max}$ of the diffusion peak. The same networks can additionally be exported in environments for agent-based simulations like NetLogo.

physics.gen-ph↗