A new lens patent for a 14mm f/3.5 lens for mirrorless cameras with APS-C sensors was recently filed by Sigma. And according to this new patent this would be a zero-distortion lens just like new Laowa lens.
Patent Publication No. 2016-139087 Published 2016.8.4 Filing date 2015.1.29
INF 200mm Focal length 13.98 13.28 F-number 3.53 3.54 Full angle of view