Kagomé Lattice Antiferromagnet Stripped to Its Basics

We study a model of the spin S = 1/2 Heisenberg antiferromagnet on a one-dimensional lattice with the local symmetry of the two-dimensional Kagomé lattice. Using three complementary approaches, it is shown that the low-energy spectrum can be described by two critical Ising models with different velocities. One of these velocities is small, leading to a strongly localized Majorana fermion. These excitations are singlet ones, whereas the triplet sector has a spectral gap.