Nature: Unexplained ‘ghost particles’ are mysteriously appearing inside a US-based high-energy physics experiment.Bloggers and theorists are already lining up explanations that involve unseen particles, hypothetical strings, or modifications of conventional physics. The finding is so controversial that about one-third of the 600-person experiment that detected it are refusing to put their names on the 69-page paper purporting its discovery, unveiled on the arXiv preprint server on 29 October.