Position space formulation for Dirac fermions on honeycomb lattice

We study how to construct Dirac fermion defined on the honeycomb lattice in position space. Starting from the nearest neighbor interaction in tight binding model, we show that the Hamiltonian is constructed by kinetic term and second derivative term of three flavor Dirac fermions in which one flavor has a mass of cutoff order and the other flavors are massless. In this formulation the structure of the Dirac point is simplified so that its uniqueness can be easily shown even if we consider the next-nearest neighbor interaction. We also show the chiral symmetry at finite lattice spacing, which protects the masslessness of the Dirac fermion, and discuss the analogy with the staggered fermion formulation.Comment: 19 pages, 7 figure

TeV-scale seesaw from a multi-Higgs model

We suggest new simple model of generating tiny neutrino masses through a TeV-scale seesaw mechanism without requiring tiny Yukawa couplings. This model is a simple extension of the standard model by introducing extra one Higgs singlet, and one Higgs doublet with a tiny vacuum expectation value. Experimental constraints, electroweak precision data and no large flavor changing neutral currents, are satisfied since the extra doublet only has a Yukawa interaction with lepton doublets and right-handed neutrinos, and their masses are heavy of order a TeV-scale. Since active light neutrinos are Majorana particles, this model predicts a neutrinoless double beta decay.Comment: 21 pages, 8 figure

Nitrides of Non‐Main Group Elements

Abstract In the last two decades, there has been a renewed interest in the chemistry of nitrides and nitridometalates. Both binary and higher nitrides MxNy have already featured prominently as refractory materials, corrosion‐ and mechanical wear‐resistant coatings, hard materials, and hard magnets; thin films are used as diffusion barriers in integrated circuits. Whereas research on binary transition metal nitrides is mostly driven by technical and economic interests, the investigation on nitridometalates primarily focuses on exploration with respect to the development of new synthetic strategies and the design of new materials. Within this field of interest, especially the nitride chemistry of rare earth metals is still comparably undeveloped. Chemical bonding in binary nitrides varies from primarily salt‐like via covalent to metallic, whereas nitridometalates are best described as containing covalent complex anions [MxNy]z− with alkali, alkaline earth, or rare earth metal cations providing electroneutrality

Proceedings Of The 23Rd Paediatric Rheumatology European Society Congress: Part Two

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