English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The Nielsen-Ninomiya theorem implies that any local, Hermitian andtranslationally invariant lattice action in even-dimensional spacetime possessan equal number of left- and right-handed chiral fermions. We argue that if onesacrifices the property of Hermiticity while keeping the locality andtranslation invariance, while imposing invariance of the action under thespace-time (PT) reversal symmetry, then the excitation spectrum of the theorymay contain a non-equal number of left- and right-handed massless fermions withreal-valued dispersion. We illustrate our statement in a simple 1+1 dimensionallattice model which exhibits a skewed 8-figure patterns in its energy spectrum.A drawback of the model is that the PT symmetry of the Hamiltonian isspontaneously broken implying that the energy spectrum contains complexbranches. We also demonstrate that the Dirac cone is robust against localdisorder so that the massless excitations in this PT-invariant model are notgapped by random space-dependent perturbations in the couplings.

The Nielsen-Ninomiya theorem, PT-invariant non-Hermiticity and single 8-shaped Dirac cone