Fat distributions with Reeb directions need not be complex contact

TL;DR

This paper constructs examples of fat (4,6)-distributions with Reeb directions that do not support complex contact structures, answering an open question and showing the space of such structures has infinite codimension.

Contribution

It provides the first explicit examples of fat distributions with Reeb directions lacking complex contact structures, and demonstrates the infinite codimension of complex-contact germs within all such distributions.

Findings

Constructed fat distributions with Reeb directions not supporting complex contact structures.

Proved the space of complex-contact germs has infinite codimension in the space of all fat (4,6)-distribution germs.

Answered an open question by A. Bhowmick.

Abstract

It is well known that every complex contact $3$-manifold, when regarded as a real manifold, gives rise to a fat $(4,6)$-distribution that admits two Reeb directions. Nonetheless, it was an open question whether the converse was true. This was not known even at the level of germs. The present work completely answers this question in the negative. We construct the first example of a fat distribution with two Reeb directions that does not support a complex contact structure anywhere, not even locally nor up to diffeomorphism. This result answers an open question by A. Bhowmick. In the second part of this work we prove a stronger result. By applying suitable $C^\infty$-perturbations to our construction, we show that the space of complex-contact germs has infinite codimension within the space of fat $(4,6)$-distribution germs with Reeb directions.