arXiv subjects

J. G. F. Campos

Publications and source records attributed to J. G. F. Campos.

5 recordsLinked to original sources

arXiv2026

Vortex-Antivortex Annihilation from BPS Equations

In this work, we introduce a vortex-impurity model that admits BPS configurations containing both vortices and antivortices and allows vortex-antivortex annihilation to be described within the moduli-space approximation. For a suitable class of impurities, the BPS equations can be mapped through a coordinate transformation onto those of the impurity-free Abelian-Higgs model. In particular, we identify nonlocalized impurities that act as mirrors, generating a vortex-antivortex pair symmetrically placed with respect to the impurity. We derive the corresponding moduli-space metric and show that, within the geodesic approximation, the pair approaches the annihilation configuration asymptotically. We further extend the construction to chains and two-dimensional arrays of alternating vortices and antivortices. Finally, we introduce radial bump impurities that produce stretched and compressed vortices with nontrivial internal magnetic structures.

hep-th↗

arXiv2026

Collision Dynamics of False-Vacuum Oscillons

We study the collision dynamics of localized oscillons in two classes of $(1+1)$-dimensional scalar field theories with metastable false vacua, a normal class with a positive quartic self-interaction term and an inverted class with a negative quartic term. We construct small-amplitude oscillon solutions around the false vacuum using the Fodor {\emph{et al.}} expansion, and show that the force between oscillons decays exponentially at large separation, with a strength modulated by their relative phase. Numerical simulations of two-oscillon collisions exhibit reflection, crossing, and formation of excited oscillons. Resonance windows occur, similar to those found in kink-antikink collisions. In the normal theory, if the oscillons have sufficient energy, the field can pass over a sphaleron barrier and evolve into a kink-antikink pair, initiating a phase transition to the true vacuum. We also simulate the collision of oscillons evolved from a slightly perturbed sphaleron.

hep-th↗

arXiv2025

Resonance with quasinormal modes in long-range kinks' collisions

We consider a rational scalar field model in (1+1)-dimensions where the long-range character of the kinks is controllable. We show via numerical simulations that kinks with long-range tails on both sides can exhibit resonance windows. The resonant energy exchange mechanism occurs via the excitation of quasinormal modes, which we obtain via a spectral analysis. Additionally, we locate a resonance window in a family of $ϕ^{10}$ models with long-range tails on both sides. Moreover, we propose a new algorithm for initializing long-range kink collisions, based on convection-diffusion dynamics.

hep-th↗

arXiv2024

Collective coordinates method for long-range kink collisions

In this paper, we explored a class of potentials with three minima that support kink solutions exhibiting one long-range tail. We analyzed antikink-kink interactions using an effective Lagrangian based on collective coordinates and compared the results to those obtained from full dynamical simulations. To this end, we constructed the collective coordinates with the antikink-kink configuration, and also a generalized Derrick mode, choosing the kink position and the Derrick mode amplitude as the moduli. For the antikink-kink configuration, we utilized the impurity ansatz proposed in \cite{campos2024collision}. We also studied the interaction of wobbling kinks where the lowest delocalized mode is excited.

hep-th↗

arXiv2018

Stochastic oscillations produce dragon king avalanches in self-organized quasi-critical systems

In the last decade, several models with network adaptive mechanisms (link deletion-creation, dynamic synapses, dynamic gains) have been proposed as examples of self-organized criticality (SOC) to explain neuronal avalanches. However, all these systems present stochastic oscillations hovering around the critical region that are incompatible with standard SOC. This phenomenology has been called self-organized quasi-criticality (SOqC). Here we make a linear stability analysis of the mean field fixed points of two SOqC systems: a fully connected network of discrete time stochastic spiking neurons with firing rate adaptation produced by dynamic neuronal gains and an excitable cellular automata with depressing synapses. We find that the fixed point corresponds to a stable focus that loses stability at criticality. We argue that when this focus is close to become indifferent, demographic noise can elicit stochastic oscillations that frequently fall into the absorbing state. This mechanism interrupts the oscillations, producing both power law avalanches and dragon king events, which appear as bands of synchronized firings in raster plots. Our approach differs from standard SOC models in that it predicts the coexistence of these different types of neuronal activity.

nlin.AO↗