Nearly Parallel G2-Structures from the Perspective of Geometric Flows
Abstract: A 3-Sasakian structure on a 7-manifold may be used to
define two distinct Einstein metrics: the 3-Sasakian metric and the
squashed Einstein metric. Both metrics are induced by nearly parallel
G2-structures which may also be expressed in terms of the 3-Sasakian
structure. Just as Einstein metrics are critical points for the Ricci
flow up to rescaling, nearly parallel G2-structures provide natural
critical points of the (rescaled) geometric flows of G2-structures
known as the Laplacian flow and Laplacian coflow. We study each of
these flows in the 3-Sasakian setting and see that their behaviour is
markedly different, particularly regarding the stability of the nearly
parallel G2-structures. We also compare the behaviour of the flows
of G2-structures with the (rescaled) Ricci flow.
This is joint work
with Jason Lotay.