If the model for the neutrinos correctly determines their original energies, it should also provide suitable values for electrons after careful calculations. The researchers took the data from an experiment in which electron beams of various energies were systematically shot at atomic nuclei at the Jefferson Lab in the US state of Virginia, and the resulting particles were comprehensively measured. Here helium, carbon and iron nuclei were of interest, which are comparable to the target objects in various neutrino detectors. The chosen electron energies also correspond to those of typical neutrino experiments. In addition, the physicists limited their analysis to events that were easy to interpret in order to reduce possible sources of error.
Despite the considerable effort, the results were sobering: the models performed very poorly in terms of delivering the correct energies of the electron beams within a tolerance range of five percent. Overall, this was achieved in less than half of the events, in the case of carbon nuclei only in about a third of all cases, and in the case of iron barely a quarter.
The theoretical understanding of the interactions of the neutrinos is evidently expandable even in the areas that seemed to have been covered quite well up to now. The exact causes of the discrepancy must now be fathomed so that the models become more reliable. This is important right now, the team emphasizes with a view to planned investigation campaigns with large-scale systems under construction: “Now that we are entering an era of precision measurements on neutrinos, it will be crucial to make the models just as accurate and reliable.” the better the raw data from future detectors, the more important it is to eliminate inaccuracies in the models for their evaluation. Otherwise the desired precision disappears under thick error bars and unnecessarily leaves much of the already mysterious neutrinos in the dark.