Muons are subatomic particles heavier than electrons. Over time, a muon "breaks up" (disintegrates) into other particles, including neutrinos and antineutrinos. Neutrinos and their antiparticle, the antineutrinos, are fundamental subatomic particles with an extremely small mass, close to zero and devoid of electric charge, which makes them invisible to electromagnetic fields.
When a neutrino hits the nucleus of an atom, it can cause that nucleus to move. That "tap" is what is called CEvNS (Coherent Elastic Neutrino-Nucleus Scattering).
In the 1970s, Daniel Z. Freedman observed that this process, the elastic coherent neutrino-nucleus scattering (CEvNS) had a higher probability than usual according to the standard model of particle physics.
However, in the 70s the phenomenon was impossible to observe, since its only signal is the slight recoil of the nucleus after the "collision" with the incident neutrino or antineutrino. Thanks to experimental advances, the COHERENT collaboration was able to measure this process for the first time in 2017 using neutrinos produced at the Oak Ridge National Laboratory (USA). Since then, COHERENT has observed the phenomenon with different detectors and improved initial accuracy.
"Our approach can also be applied to recent CEvNS measurements with reactor and solar neutrinos to study their respective production processes, although this will require specific analysis due to the particularities of each case."
Now, a new work published in the journal Physical Review Letters, led by a team from the Institute of Corpuscular Physics (IFIC), located in the scientific-academic area of the University of Valencia Science Park (PCUV), demonstrates for the first time that COHERENT data also allows important aspects associated with neutrino production to be analysed, including possible new interactions. In particular, the team shows that it is possible to study muon decay by observing how emitted neutrinos and antineutrinos are dispersed over atomic nuclei through this "striking" process called CEvNS. With the data from the COHERENT experiment, Michel’s parameters have been extracted for the first time, which describe the energy distribution of the antineutrino. These parameters were introduced 75 years ago for electrons and 30 years ago for neutrinos, and are now being extended for the first time to antineutrinos.
The work has been carried out by a IFIC team composed of Sergio Cruz-Alzaga, Martín González-Alonso and Suraj Prakash, in collaboration with Víctor Bresó-Pla, postdoctoral researcher at Harvard University, he obtained his PhD at IFIC in 2023 and developed part of this research while belonging to the University of Heidelberg. "In the first publication we have focused on muon disintegration, assuming also the preservation of leptonic flavor, with the objective to present the idea and show its usefulness" note the authors. In addition, in a second paper published in the Journal of High Energy Physics (JHEP), the team extends the study by comprehensively analysing all possible interactions.
"Our approach can also be applied to recent CEvNS measurements with reactor and solar neutrinos to study their respective production processes, although this will require a specific analysis due to the particularities of each case," note the authors.
Taken together, these works show an interesting connection between neutrino physics and taste physics, extending the application of CEvNS measurements as a new tool for fundamental physics. In addition, CEvNS measurements open the door to practical applications such as remote monitoring of nuclear reactors and development of compact neutrino detectors.
Source: IFIC