What happens if a student busts Dallas Fort Worth bravo airspace?
Just to make it perfectly clear:

If you accidentally enter a controlled airspace without clearance, as soon as you realise what has happened, the first thing you do is contact the responsible ATC unit! Period.

Panicking, initiating a rapid descend to leave the airspace or simply pretending it didn't happen is extremely bad airmanship, and will surely get you in trouble if you get caught. On the other hand, admitting you made an honest mistake and asking ATC what the best solution is might still get you in trouble in some countries, but it is definitely the safest solution for everyone.

Depending on the exact details of the airspace infringement, it may be extremely dangerous if you try to solve the problem on your own. By suddenly descending to leave the airspace, you risk colliding with traffic below you. If the airspace in question is of a military kind, turning a blind eye to your mistake and maintaining radio silence will potentially result in a visit from some aircraft with a lot more weapons than yours.

Anyone can get lost and make mistakes. If you do, ATC is there to help you - not to punish you for an honest mistake. Make use of that help!

As for procedures about which forms need to be filed after an incident like this, I will leave it to someone with knowledge about FAA specific procedures to answer.

You can read more about Airspace Infringements at SKYbrary.