(Tried Googling this - made little headway.)
As I understand it, the man carrying the ball is down when a knee (or, I believe, his butt) touches the ground. But how about if the ball touches the ground? Suppose he stumbles, but manages to catch himself in such a way that only his hands and the ball touch the ground? (And the ball clearly stays in his posession - no hint of a fumble.) Can he continue running, or is the play dead at that spot?
Since that was how players originally actually scored a touchdown (touching the ball down on the ground), I would assume it’s still a dead ball and the play ends.
I don’t think I’ve ever seen it happen, either in the NFL or college football.
The relevant rule (from here[warning: PDF]):
Looks to me as if it’s ok to prop yourself up with the ball. The rulebook lists 17 different ways for a play to become dead, and none of them include a ball still in a player’s possession touching the ground.
Where I bet you went wrong is in trying to google your specific question. You should’ve googled “college football rules” or “ncaa football rules,” either of which will lead you straight to the rulebook.
I did, but wasn’t able to get a clear-cut answer.
Your research into the 17 ways a play can become dead is significant.
Why would you assume that? The touch-down comes from rugby, and when the ball is touched to the ground somewhere that’s not in the try zone, it has exactly zero significance to the play.
The player is definitely NOT down in this scenario. As long as he has clearly established control of the ball in the first place (assuming a forward pass - if it’s a hand-off even that much is not necessary), then the ball touching the ground means nothing. If it IS a forward pass, then there might be some question as to whether or not it was an incomplete pass when the ball hit the ground, but that doesn’t really seem to be the focus of your question.
The play is not dead until the player hits the ground (or goes out of bounds or into the endzone).
It happened in a Michigan State Game just this season. The one against University of Michigan, IIRC.