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Magnetic fields can be introduced into discrete models of quantum systems by the Peierls substitution. For tight-binding Hamiltonians, the substitution results in a set of (Peierls) phases that are usually calculated from the magnetic vector potential. As the potential is not unique, a convenient gauge can be chosen to fit the geometry and simplify calculations. However, if the magnetic field is non-uniform, finding a convenient gauge is challenging. In this work we propose to bypass the vector potential determination by calculating the Peierls phases exclusively from the gauge-invariant magnetic flux. The phases can be assigned following a graphic algorithm reminiscent of the paper and pencil game "dots and boxes". We showcase the method implementation by calculating the interference phenomenon in a modified Aharonov-Bohm ring and propose a phase assignation alternative to the Landau gauge to reproduce the Half Integer Quantum Hall Effect in graphene. A non-uniform magnetic field case is addressed by considering a multi-domain Chern insulator to study the effects of domain walls in resistance and current quantization. It is found that adding decoherence and a finite temperature into the model results in quantized resistances that are in good agreement with experiments made with multi-domain intrinsic topological insulators., Comment: 33 pages, 12 figures

Social media platforms have played a key role in weaponizing the polarization of social, political, and democratic processes. This is, mainly, because they are a medium for opinion formation. Opinion dynamic models are a tool for understanding the role of specific social factors on the acceptance/rejection of opinions because they can be used to analyze certain assumptions on human behaviors. This work presents a framework that uses concurrent set relations as the formal basis to specify, simulate, and analyze social interaction systems with dynamic opinion models. Standard models for social learning are obtained as particular instances of the proposed framework. It has been implemented in the Maude system as a fully executable rewrite theory that can be used to better understand how opinions of a system of agents can be shaped. This paper also reports an initial exploration in Maude on the use of reachability analysis, probabilistic simulation, and statistical model checking of important properties related to opinion dynamic models.

Hackathons and software competitions, increasingly pivotal in the software industry, serve as vital catalysts for innovation and skill development for both organizations and students. These platforms enable companies to prototype ideas swiftly, while students gain enriched learning experiences, enhancing their practical skills. Over the years, hackathons have transitioned from mere competitive events to significant educational tools, fusing theoretical knowledge with real-world problem-solving. The integration of hackathons into computer science and software engineering curricula aims to align educational proficiencies within a collaborative context, promoting peer connectivity and enriched learning via industry-academia collaborations. However, the infusion of advanced technologies, notably artificial intelligence (AI), and machine learning, into hackathons is revolutionizing their structure and outcomes. This evolution brings forth both opportunities, like enhanced learning experiences, and challenges, such as ethical concerns. This study delves into the impact of generative AI, examining its influence on student's technological choices based on a case study on the University of Iowa 2023 event. The exploration provides insights into AI's role in hackathons, and its educational implications, and offers a roadmap for the integration of such technologies in future events, ensuring innovation is balanced with ethical and educational considerations., Comment: 8491 words, 23 pages, 12 figures

Bound states in the continuum (BICs) are quantum states with normalizable wave functions and energies that lie within the continuous spectrum for which extended or dispersive states are also available. These special states, which have shown great applicability in photonic systems for devices such as lasers and sensors, are also predicted to exist in electronic low-dimensional solid-state systems. The non-trivial topology of materials is within the known mechanisms that prevent the bound states to couple with the extended states. In this work we search for topologically protected BICs in a quantum Hall bar with an anti-dot formed by a pore far from the borders of the bar. The bound state energies and wavefunctions are calculated by means of the Recursive S-Matrix method. The resulting bound state energies coexist with extended states and exhibit a pattern complimentary to the Hofstadter butterfly. A symmetry-breaking diagonal disorder was introduced, showing that the BICs with energies far from the Landau levels remain robust. Moreover, the energy difference between consecutive BICs multiplied by the anti-dot perimeter follows the same curve despite disorder. Finally, a BIC-mediated current switching effect was found in a multi-terminal setup, which might permit their experimental detection., Comment: 5 figures

We report a novel method to find bound states in general tight-binding Hamiltonians with semi-infinite leads. The method is based on the recursive S-matrix method, which allows us to compute iteratively the S-matrix of a general system in terms of the S-matrices of its subsystems. We establish the condition that the S-matrices of the subsystems must accomplish to have a bound state at energy E. Energies that accomplish this relation, can be determined with high accuracy and efficiency by using the Taylor series of the S-matrices. The method allows us to find bound states energies and wavefunctions in (BIC) and out (BOC) of the continuum, including degenerate ones. Bound states in nanoribbons with wider sections are computed for square and honeycomb lattices. Using this method, we verify the bound states in a graphene nanoribbon with two quantum-dot-like structures which has been reported to have BICs by using another technique. However, this new analysis reveals that such BICs are double, one with even and the other with odd wavefunction, with slightly separated energies. In this way, the new method can be used to efficiently find new BICs and to improve precision in previously reported ones., Comment: 17 pages, 6 figures

We propose a divide-and-conquer algorithm to find recursively the Scattering matrix of general tight-binding structures. The Scattering matrix allows a direct calculation of transport properties in mesoscopic systems by using the Landauer formula. The method is exact, and by analyzing the performance of the algorithm in square, triangular and honeycomb lattices, we show a significant improvement in comparison to other state-of-the-art recursive and non-recursive methods., Comment: 12 pages, 3 figures

There is a great diversity of formal models to understand the dynamics of transport and vehicular flow on a road. Many of these models are inspired by the dynamics of flows governed by partial differential equations. However, it is possible to simplify these models to ordinary equations by considering constant variations in some of the input variables in this type of models. However, given that these types of systems present discrete changes when the vehicle density is altered in some sections of the lane, it seems reasonable to make use of hybrid systems to better understand the evolution of these dynamics. In this work we are interested in making use of dynamic differential logic to formally verify one of these models proposed in ordinary equations. This verification will be done through a proof assistant specially designed for hybrid systems called KeYmaera. Once we adapt the model to a hybrid system representation we proceed to use KeYmaera to verify that the proposed model is formally correct.

The importance of the working document is that it allows the analysis of the information and the status of cases associated with (SARS-CoV-2) COVID-19 as open data at the municipal, state and national level, with a daily record of patients, according to a age, sex, comorbidities, for the condition of (SARS-CoV-2) COVID-19 according to the following characteristics: a) Positive, b) Negative, c) Suspicious. Likewise, it presents information related to the identification of an outpatient and / or hospitalized patient, attending to their medical development, identifying: a) Recovered, b) Deaths and c) Active, in Phase 3 and Phase 4, in the five main population areas speaker of indigenous language in the State of Veracruz - Mexico. The data analysis is carried out through the application of a data mining algorithm, which provides the information, fast and timely, required for the estimation of Medical Care Scenarios of (SARS-CoV-2) COVID-19, as well as for know the impact on the indigenous language-speaking population in Mexico., Comment: 20 pages, 1 figure, 2 maps

The Landauer formula allows us to describe theoretically the conductance in terms of the transmission function in a mesoscopic system. We propose a general method to evaluate the transmission function in the complex domain for systems connected to semi-infinite atomic chains. This reveals the presence of complex-conjugated pairs of simple poles that are responsible for transmission peaks in the real-domain evaluations. This leads us to formulate a closed-form expression for the transmission function., Comment: 6 pages, 4 figures

A novel efficient method to calculate the scattering matrix (SM) of arbitrary tight-binding Hamiltonians is proposed, including cases with multiterminal structures. In particular, the SM of two kind of fundamental structures are given, which can be used to obtain the SM of bigger systems iteratively. Also, a procedure to obtain the SM of layer-composed periodic leads is described. This method allows renormalization approaches, which permits computations over macroscopic length systems without introducing additional approximations. Finally, the transmission coefficient of a ring-shaped multiterminal system and the transmission function of a square-lattice nanoribbon with a reduced width region are calculated., Comment: 7 figures

In this paper, we propose a method to calculate the exact Taylor series of the scattering matrix in general multiterminal tight-binding systems to arbitrary order N, which allows us to find the Taylor expansion of Landauer conductance in mesoscopic systems. The method is based on the recursive scattering matrix method (RSMM) that permits us to find the scattering matrix of a system from the scattering matrices of its subsystems. Following ideas of automatic differentiation, we determine expressions for the sum, product, inverse, and diagonalization of a matrix Taylor expansion, and use them into the RSMM to find Taylor series of scattering matrices. The method is validated by obtaining the transmission function of atomic chains with site defects and graphene nanoconstrictions. Finally, an analysis of convergence radius and error estimations of these Taylor expansions is presented., Comment: 3 figures

In this paper we investigate CP violation in charged decays of $D$ meson. Particularly, we study the direct CP asymmetry of the Cabibbo favored non-leptonic $D^+ \rightarrow \bar K^0 \pi^+$ and the doubly Cabibbo-suppressed decay mode $D^+ \rightarrow K^0 \pi^+$ within standard model, two Higgs doublet model with generic Yukawa structure and left right symmetric models. In the standard model, we first derive the contributions from box and di-penguin diagrams contributing to their amplitudes which are relevant to the generation of the weak phases essential for non-vanishing direct CP violation. Then, we show that these phases are so tiny leading to a direct CP asymmetry of order $10^{-11}$ in both decay modes. Regarding the two Higgs doublet model with generic Yukawa structure and after taking into account all constraints on the parameter space of the model, we show that the enhanced direct CP asymmetries can be 6 and 7 orders of magnitudes larger than the standard model prediction for $D^+ \rightarrow \bar K^0 \pi^+$ and $D^+ \rightarrow K^0 \pi^+$ respectively. Finally, within left right symmetric models, we find that sizable direct CP asymmetry of ${\mathcal O } (10^{-3})$ can be obtained for the decay mode $D^+ \rightarrow \bar K^0 \pi^+$ after respecting all relevant constraints., Comment: 20 pages, 2 figures. arXiv admin note: text overlap with arXiv:1710.00413

This paper presents an accurate highly efficient method for solving the bound states in the one-dimensional Schr\"odinger equation with an arbitrary potential. We show that the bound state energies of a general potential well can be obtained from the scattering matrices of two associated scattering potentials. Such scattering matrices can be determined with high efficiency and accuracy, leading us to a new method to find the bound state energies. Moreover, it allows us to find the associated wavefunctions, their norm, and expected values. The method is validated by comparing solutions of the harmonic oscillator and the hydrogen atom with their analytical counterparts. The energies and eigenfunctions of Lennard-Jones potential are also computed and compared to others reported in the literature. This method is highly parallelizable and produces results that reach machine precision with low computational effort., Comment: 16 pages, 5 figures