Dynamical Solution of the Strong CP Problem
by
Online (zoom)
KIAS
Title: Dynamical Solution of the Strong CP Problem
Speaker: Prof. Gerrit Schierholz (DESY)
Abstract: The vacuum of quantum chromodynamics has an incredibly rich structure at the nonperturbative level, which is intimately connected with the topology of gauge fields, and put to a test by the strong CP problem. I investigate the long-distance properties of the theory in the presence of a topological $\theta$ term. This is done on the lattice, using the gradient flow to isolate the long-distance modes in the functional integral measure and tracing it over successive length scales. The gradient flow serves as a particular, infinitesimal realization of the coarse-graining step of momentum space RG transformations. I find that the color fields produced by quarks and gluons are screened for vacuum angles $|\theta| ≳ 0$, not unexpectedly, thus providing a natural solution of the strong CP problem.
