Dr. Greg Pemberton was one of a team of Fermi-Lab physicists who accidentally confirmed the Super-Asymmetry paper published by Sheldon and Amy. The unexplained differences in their data during an experiment with kaon particles confirmed Sheldon and Amy's work. The data differences were pointed out by a colleague and the Fermi-Lab physicists don't even understand their super-asymmetry work. They are more excited about travelling and appearing on the TV show Ellen. Also, Fermi-Lab plans on submitting their two colleagues and Sheldon in their Nobel Prize submission, leaving out the neuroscientist Amy.
His other Fermi-Lab colleague is Dr. Campbell.
The doctor returns in "The Laureate Accumulation" trying to fraudulently take credit for Sheldon and Amy's work. He and Dr. Campbell appear on Ellen without explaining their work. Also, they show up at Sheldon and Amy's reception and complain about being called imposters (even though in truth, they are).
In "The Plagiarism Schism", Dr. Pemberton is disqualified from Nobel Prize consideration and his career is over because Dr. Campbell told the Interent and thus the Nobel Committee that Pemberton plagiarized his thesis - a piece of information originally known by Barry Kripke, from whom Leonard obtained it and gave to Sheldon and Amy. Dr. Campbell then claims to Sheldon and Amy that he was hooking up with Pemberton's ex-wife. That was just a rumor.