High Energy Physics Seminar

Chiral symmetry is hard to engineer on the lattice. The origin of this problem can be traced to the Nielsen Ninomiya theorem which in its most naive form forbids the existence of unpaired Weyl fermions on the lattice. As a result, a general prescription for regulating chiral gauge theories (e.g. the standard model) on the lattice has remained elusive for the last fifty years. I will discuss a recent proposal that has brought us very close to solving this long-standing problem. The proposal involves considering the discretized Hamiltonian for a Wilson fermion in (2+1) dimensions with a (1+1) dimensional boundary and continuous time. Remarkably, the low-lying boundary spectrum is Weyl-like: it has a linear dispersion relation and definite chirality and circulates in only one direction around the boundary. I discuss how these results while being consistent with the Nielsen Ninomiya theorem remove a major obstacle facing the program of regulating chiral gauge theories on the lattice.

The talk is in 469 Lauritsen.

Contact theoryinfo@caltech.edu for Zoom link.