Is the beryllium/helium ATOMKI anomaly due to a new particle?
Jan 2, 2040
See here for an overview: https://en.wikipedia.org/wiki/X17_particle. In short, decays of beryllium and helium nuclei do not match what is predicted from nuclear physics. As I write this, the result has not yet been independently reproduced. The anomalous decays are consistent with a new fundamental particle of mass ~17 MeV (hence the name). However, there are other possibilities. Most obviously, the experimenters could have made an error. It is also possible that the nuclear theory predictions are untrustworthy---although efforts to explain it in terms of ordinary nuclear physics have been failing for 5 years (see e.g. https://arxiv.org/abs/1703.04588). This question resolves YES if the effect is reproduced and independent evidence (i.e. from a different type of experiment) indicates that this is indeed the result of a new particle with mass near 17 MeV. This question resolves NO if the experiment fails to reproduce, or the effect is determined to be the result of ordinary nuclear physics. If the experiment has not been reproduced by the close date, this question will resolve NO.