Well, then, the fact that Pettersson acquired United States citizenship not too long ago means that American captain Davis Love III is looking hard at adding Pettersson to Team USA, right? Wrong. Pettersson isn't eligible for Team USA.
Pettersson is a dual national. He was born in Sweden and maintains his Swedish citizenship, but has lived in the United States since his junior year of high school and acquired American citizenship early in 2012.
He has played almost exlusively in PGA Tour events since joining the USPGA Tour in 2003. And that's the problem for him regarding Team Europe. Only members of the European Tour are eligible to play for Europe in the Ryder Cup. Pettersson isn't a member, and hasn't played a "regular" Euro Tour event (as opposed to a major or WGC tournament) in half a decade.
As for Team USA, naturalized American citizens are eligible to play Ryder Cup for the United States - but only if they acquired citizenship before turning 18. So Pettersson strikes out on that count, too.
Pettersson has made comments that make it clear he'd like to play for Europe. But don't feel too bad for him - he could change the situation if he wanted to badly enough. Other Europeans living in the U.S. - Luke Donald, Ian Poulter, Paul Casey to name a few - have no trouble playing primarily on the PGA Tour while also meeting European Tour eligibility requirements. If Pettersson played in the four majors and three U.S.-based WGC tournaments, he'd need only make five appearances in "regular" European Tour events to meet the Euro Tour's membership requirement.
But Pettersson is happy playing the USPGA. He has a family and a life in North Carolina that he doesn't want to take more time away from. He's made his choice to remain a Swedish-American golfer without a Ryder Cup team.