Solutions of the Laplacian flow and coflow of a locally conformal parallel $$\mathrm {G}_2$$-structure

Abstract

We study the Laplacian flow of a $$\mathrm {G}_2$$ -structure where this latter structure is claimed to be locally conformal parallel. The first examples of long time solutions of this flow with the locally conformal parallel condition are given. All of the solutions are ancient and Laplacian soliton of shrinking type. These examples are one-parameter families of locally conformal parallel $$\mathrm {G}_2$$ -structures on rank-one solvable extensions of six-dimensional nilpotent Lie groups. The found solutions are used to construct long time solutions to the Laplacian coflow starting from a locally conformal parallel structure. We also study the behavior of the curvature of the solutions obtaining that for one of the examples the induced metric is Einstein along all the flow (resp. coflow).