He lost himself in his new research.
我を忘れる in this context is incorrect. It should be:
我を忘れる implies “be totally fascinated, lose one’s mind and become irrational or inattentive” (see the definition).
没 of 没頭する is “to bury/immerse” and 頭 is “head”. So, 没頭する means “to totally devote one’s time and effort to a certain activity”. The person is just diligent, not crazy nor dull.