# Dynamical solution of the strong CP problem

## Gerrit Schierholtz (DESY Hamburg)

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. We 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. We find that the color fields produced by quarks and gluons are screened, and confinement is lost, for vacuum angles $|\theta| > 0$, thus providing a natural solution of the strong CP problem.

Seminar room II, HISKP, 3rd floor