The credible measurements of new physics that are later ruled out are generally made at the edge of what is technically possible. Limiting and estimating all s

The credible measurements of new physics that are later ruled out are generally made at the edge of what is technically possible. Limiting and estimating all sources of systematic uncertainty is our job, but it is a difficult one. It is generally possible to make uncertainty estimates that are so conservative as to be beyond reproach, but to do so also makes progress almost impossible. I haven't yet had a chance to dig into this particular anomaly at 17 MeV, so what follows is speculation: It is a surprising mass range for anything new to emerge. The coupling constant, or its mechanism, must be so weak that it would avoid discovery in a century of other nuclear-physics and particle-physics experiments that have access to that energy scale. I am surprised that there hasn't yet been a devastating constraint on this thing from the electron-positron collider world.