**Improving Center Vortex Detection by Usage of Center Regions as Guidance for the Direct Maximal Center Gauge**

#### **Rudolf Golubich and Manfried Faber \***

Atominstitut, Technische Universität Wien, Operngasse 9, A-1040 Wien, Austria; rudolf.golubich@gmail.com **\*** Correspondence: faber@kph.tuwien.ac.at

Received: 19 November 2019; Accepted: 9 December 2019; Published: 11 December 2019

**Abstract:** The *center vortex model* of quantum chromodynamic states that vortices, a closed color-magnetic flux, percolate the vacuum. Vortices are seen as the relevant excitations of the vacuum, causing confinement and dynamical chiral symmetry breaking. In an appropriate gauge, as *direct maximal center gauge*, vortices are detected by projecting onto the center degrees of freedom. Such gauges suffer from Gribov copy problems: different local maxima of the corresponding gauge functional can result in different predictions of the string tension. By using nontrivial center regions—that is, regions whose boundary evaluates to a nontrivial center element—a resolution of this issue seems possible. We use such nontrivial center regions to guide simulated annealing procedures, preventing an underestimation of the string tension in order to resolve the Gribov copy problem.

**Keywords:** quantum chromodynamics; confinement; center vortex model; string tension; Gribov copy problem

**PACS:** 11.15.Ha; 12.38.Gc
