The Standard model and the lattice

by Srimoyee Sen

Wednesday 11 Dec 2024, 14:00 → 16:00 Europe/Berlin

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. Moreover, the formulation also requires the QCD sector to respect CP.