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We investigate Floquet engineering in a sawtooth chain -- a minimal model hosting a nearly flat band endowed with nontrivial quantum geometry -- coupled to driven surface polaritons. In this paradigmatic flat band model, light-matter coupling to a flat band is enabled by quantum geometry despite the vanishing band velocity and band curvature. We show that light polarization and finite momentum transfer in polaritonic settings provide sufficient tunability to flatten or unflatten bands, with sometimes drastic band structure modifications beyond what is attainable with laser pulses in free space. Possible implications for light-driven phenomena in prototypical flat-band moir\'e or kagome materials are discussed., Comment: 8 pages, 3 figures, including a short appendix

Magnetic van der Waals (vdW) materials have opened new frontiers for realizing novel many-body phenomena. Recently NiPS3 has received intense interest since it hosts an excitonic quasiparticle whose properties appear to be intimately linked to the magnetic state of the lattice. Despite extensive studies, the electronic character, mobility, and magnetic interactions of the exciton remain unresolved. Here we address these issues by measuring NiPS3 with ultra-high energy resolution resonant inelastic x-ray scattering (RIXS). We find that Hund's exchange interactions are primarily responsible for the energy of formation of the exciton. Measuring the dispersion of the Hund's exciton reveals that it propagates in a way that is analogous to a double-magnon. We trace this unique behavior to fundamental similarities between the NiPS3 exciton hopping and spin exchange processes, underlining the unique magnetic characteristics of this novel quasiparticle., Comment: 11 pages accepted in Nature Communications

We study conformal mappings in the Grushin plane and provide a number of their characterizations in terms of the Sobolev mappings and their geometry. Furthermore, we connect conformality on the Grushin plane with conformality on the complex plane by using the Meyerson map. Among applications we discuss admissible curves and length-distortion estimates in the Grushin plane, as well as the Carath\'eodory extension theorem., Comment: 16 pages, 4 figures

Using a graph representation of classical logic, the paper shows that the liar or Yablo pattern occurs in every semantic paradox. The core graph theoretic result generalizes theorem of Richardson, showing solvability of finite graphs without odd cycles, to arbitrary graphs which are proven solvable when no odd cycles nor patterns generalizing Yablo's occur. This follows from an earlier result by a new compactness-like theorem, holding for infinitary logic and utilizing the graph representation., Comment: The proof of the main Theorem 3.7 has some flaws. A minor one, which can be fixed, is the choice of \mathcal{H} as "the set of all sinkless induced subgraphs of H having finitely many ends." A more serious one is that the proof could be used to establish an untrue claim. It is not clear yet what specific mistake causes it

Digraphs provide an alternative syntax for propositional logic, with digraph kernels corresponding to classical models. Semikernels generalize kernels and we identify a subset of well-behaved semikernels that provides nontrivial models for inconsistent theories, specializing to the classical semantics for the consistent ones. Direct (instead of refutational) reasoning with classical resolution is sound and complete for this semantics, when augmented with a specific weakening which, in particular, excludes Ex Falso. Dropping all forms of weakening yields reasoning which also avoids typical fallacies of relevance.