Spin g-factor due to electronic interactions in graphene

The gyromagnetic factor is an important physical quantity relating the magnetic-dipole moment of a particle to its spin. The electron spin g-factor in vacuo is one of the best model-based theoretical predictions ever made, showing agreement with the measured value up to ten parts per trillion. However, for electrons in a material the g-factor is modified with respect to its value in vacuo because of environment interactions. Here, we show how interaction effects lead to the spin g-factor correction in graphene by considering the full electromagnetic interaction in the framework of pseudo-QED. We compare our theoretical prediction with experiments performed on graphene deposited on SiO2 and SiC, and we find a very good agreement between them.Comment: Improved version of the manuscript; valley g-factor part has been remove

Unitarity of theories containing fractional powers of the d'Alembertian operator

We examine the unitarity of a class of generalized Maxwell U(1) gauge theories in (2+1) D containing the pseudodifferential operator $\Box^{1-\alpha}$, for $\alpha \in [0,1)$. We show that only Quantum Electrodynamics (QED$_3$) and its generalization known as Pseudo Quantum Electrodynamics (PQED), for which $\alpha =0$ and $\alpha = 1/2$, respectively, satisfy unitarity. The latter plays an important role in the description of the electromagnetic interactions of charged particles confined to a plane, such as in graphene or in hetero-junctions displaying the quantum Hall effect.Comment: 6 pages, no figure

Interaction Induced Quantum Valley Hall Effect in Graphene

We use Pseudo Quantum Electrodynamics (PQED) in order to describe the full electromagnetic interaction of the p-electrons of graphene in a consistent 2D formulation. We first consider the effect of this interaction in the vacuum polarization tensor or, equivalently, in the current correlator. This allows us to obtain the dc conductivity after a smooth zero-frequency limit is taken in Kubo's formula.Thereby, we obtain the usual expression for the minimal conductivity plus corrections due to the interaction that bring it closer to the experimental value. We then predict the onset of an interaction-driven spontaneous Quantum Valley Hall effect (QVHE) below a critical temperature of the order of $0.05$ K. The transverse (Hall) valley conductivity is evaluated exactly and shown to coincide with the one in the usual Quantum Hall effect. Finally, by considering the effects of PQED, we show that the electron self-energy is such that a set of P- and T- symmetric gapped electron energy eigenstates are dynamically generated, in association with the QVHE.Comment: 5 pages + supplemental materia

Polychaete research in Brazil: a bibliometric analysis

This article shows a comprehensive bibliometric analysis of the literature on polychaetes from Brazil, with a focus onthe growth of the field, publication venues, citation patterns, the collaboration among the Brazilian community andforeign researchers, and the main research topics over time. The analysis was based on a corpus of 568 articlespublished in 144 journals, covering a period from 1966 to 2022. The results reveal significant growth in the field,with a surge in publications particularly in the last decade. The top journals for publishing include Zootaxa, JMBA,and Zoologia. However, despite this growth, the overall impact of the research output remains somewhat limited,with most articles receiving relatively low numbers of citations, and those with more citations have broader researchquestions. This research community directed its efforts especially to taxonomy and phylogenetics research,community ecology, and physiology (ecotoxicology). These topics formed a common ground for more specializedthemes. International collaboration was driven by research specialization, better infrastructure, and fundingof developed countries. However, seeking collaborations with countries from the global south can also enrich theresearch conducted by the Brazilian community and stimulate new scientific inquiries. Embracing greater creativityand audacity as well as pursuing common goals, should yet enhance the quality of scientific research and sustainthe remarkable growth and consolidation of this renowned research communit