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"Electromagnetism"
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What is electromagnetism?
Describes the core concepts of electromagnetism and their many applications in everyday life, from watching television to using a computer, and suggests related activities.
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Analysis of the Formula omitted molecular pentaquark state by its electromagnetic properties
We are systematically studying the electromagnetic characteristics of multiquark systems to shed light on their internal structure, whose nature and quantum numbers are controversial. In this study, we investigate the magnetic dipole, electric quadrupole, and magnetic octupole moments of the [Formula omitted] state within the context of the QCD light-cone sum rule. During this analysis, we posit that the [Formula omitted] state assumes a molecular structure with quantum numbers [Formula omitted]. The extracted outcomes are given as [Formula omitted], [Formula omitted], and [Formula omitted]. The findings of this study, when considered alongside other pertinent characteristics, may assist in elucidating the nature of this controversial phenomenon.
Journal Article
Regular black holes from analytic Formula omitted
We construct regular black holes and horizonless spacetimes that are geodesically complete and satisfy the dominant energy condition from Einstein- [Formula omitted] gravities with several classes of analytic [Formula omitted] functions that can be viewed as perturbations to Maxwell's theory in weak field limit. We establish that regular black holes with special static metric ( [Formula omitted]) violate the strong energy condition and such a regular black hole with Minkowski core violates the null energy condition. We develop a formalism to perform electromagnetic duality transformations in [Formula omitted]. We obtain two new explicit examples where the duality is a symmetry. We study the properties of the corresponding dyonic black holes. We study the geodesic motions of a particular class of solutions that we call horizonless or black hole repulsons.
Journal Article
High-Performance NiO/PANI/ZnNbsub.2Osub.6 Composites for EMI Shielding: Structural Insights and Microwave Shielding Effectiveness in the Sub-8 GHz Range
The increasing demand for high-frequency applications and the widespread use of electromagnetic (EM) waves in communication systems necessitate the development of effective electromagnetic interference (EMI) shielding materials. This study investigates the structural and shielding effectiveness properties of novel polyaniline (PANI)-based NiO/ZnNb[sub.2]O[sub.6] composites for sub-8 GHz applications. NiO and ZnNb[sub.2]O[sub.6] were synthesized via conventional solid-state reactions and combined with PANI to form composites with varying compositions. X-ray diffraction (XRD) confirmed the successful formation of single-phase NiO and ZnNb[sub.2]O[sub.6], while scanning electron microscopy (SEM) revealed well-defined microstructures, contributing to enhanced shielding efficiency. Shielding effectiveness (SE) measurements were performed across the 0–8 GHz frequency range using a vector network analyzer. Among the compositions tested, the epoxy-based NiO-ZnNb[sub.2]O[sub.6] (75–25% by weight) with a 1:1 PANI ratio exhibited the highest SE value of −41.16 dB (decibels) at 6.24 GHz, demonstrating superior attenuation of EM waves. The observed shielding efficiency is attributed to multiple reflection effects, dipole interactions, and the conductive network formed by PANI. These findings highlight the potential of NiO/PANI/ZnNb[sub.2]O[sub.6] composites as cost-effective, high-performance EMI shielding materials for next-generation microwave communication and electronic applications. Further optimization and hybridization approaches are recommended to enhance performance for broader frequency bands.
Journal Article
Resonance contributions Formula omitted for the three-body decays Formula omitted
We study the contributions for the [Formula omitted] and [Formula omitted] originating from the intermediate states [Formula omitted] and [Formula omitted] in the charmless three-body decays [Formula omitted], with [Formula omitted], in the perturbative QCD approach. The subprocesses [Formula omitted] are introduced into the distribution amplitudes of [Formula omitted] system via the kaon electromagnetic form factors with the coefficients taken from the fitted results. The predictions of the branching fractions for the decays [Formula omitted] with the intermediate state [Formula omitted] decays into [Formula omitted] or [Formula omitted] are about [Formula omitted] of the corresponding results for the quasi-two-body decays [Formula omitted] in this work.
Journal Article
The cross section of Formula omitted as a litmus test of isospin violation in the decays of vector charmonia into Formula omitted
Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay [Formula omitted], where [Formula omitted] is a vector charmonium, and of the reaction [Formula omitted] at the [Formula omitted] mass, are parametrized by the same electromagnetic coupling. It follows that, the modulus of such a coupling can be extracted from the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, [Formula omitted] and [Formula omitted], it is found that, especially in the case of [Formula omitted], there is a substantial discrepancy between the values of the modulus of the same electromagnetic coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of isospin-violating contributions driven by two different mechanisms, that, however, appear to be more favored in the [Formula omitted] than in the [Formula omitted] decays.
Journal Article