Subatomic particle appear to defy Standard Model point to undiscovered force

I found a press release with slightly more info (in a human friendly language): https://cmns.umd.edu/news-events/features/3188

I think this is the preprint: http://arxiv.org/abs/1506.08614

IIUC it's only a 2 sigma. It's not so rare that a 2 sigma just disappear with more data, because it was a statistical fluke. So don't get too attached to this result for now.