Though I’ve never worked with carbon, I’ve done more than my share of fiberglass work. I’d have no qualms about cleaning, sanding and reattaching that then reinforcing it with laid up pieces of fiberglass. I’d get the smallest container of west system epoxy I could find. You won’t need much. Like someone else mentioned, mix in some colloidal silica until it’s a peanut butter consistency, that’s your glue. Then reinforce it with some fiberglass. If you’ve never worked with these materials, do a practice run on some scrap. It’s hard to tell from the pics, but it seems like an easy repair. I guess you could use JB weld, but for some reason I just don’t trust it as much. I don’t really have a reason why, I’ve just had much more experience with west system epoxy. Much like painting, good prep work is essential. Clean with acetone, lightly scuff mating surfaces with medium grit sandpaper clean again with acetone then have at it. You may need to figure out how to clamp hold everything in place to keep it from sliding out of position as the epoxy sets.