Coherent scattering and macroscopic coherence: implications for neutrino, dark matter and axion detection
Abstract
We study the question of whether coherent neutrino scattering can occur on macroscopic scales, leading to a significant increase of the detection cross section. We concentrate on radiative neutrino scattering on atomic electrons (or on free electrons in a conductor). Such processes can be coherent provided that the net electron recoil momentum, i.e. the momentum transfer from the neutrino minus the momentum of the emitted photon, is sufficiently small. The radiative processes is an attractive possibility as the energy of the emitted photons can be as large as the momentum transfer to the electron system and therefore the problem of detecting extremely low energy recoils can be avoided. The requirement of macroscopic coherence severely constrains the phase space available for the scattered particle and the emitted photon. We show that in the case of the scattering mediated by the usual weak neutral current and charged current interactions this leads to a strong suppression of the elementary cross sections and therefore the requirement of macroscopic coherence results in a reduction rather than an increase of the total detection cross section. However, for the νe scattering mediated by neutrino magnetic or electric dipole moments coherence effects can actually increase the detection rates. Effects of macroscopic coherence can also allow detection of neutrinos in 100 eV — a few keV energy range, which is currently not accessible to the experiment. A similar coherent enhancement mechanism can work for relativistic particles in the dark sector, but not for the conventionally considered nonrelativistic dark matter.
 Publication:

Journal of High Energy Physics
 Pub Date:
 October 2018
 DOI:
 10.1007/JHEP10(2018)045
 arXiv:
 arXiv:1806.10962
 Bibcode:
 2018JHEP...10..045A
 Keywords:

 Neutrino Physics;
 Beyond Standard Model;
 High Energy Physics  Phenomenology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Experiment;
 Nuclear Experiment
 EPrint:
 LaTeX, 31 page, 2 figures. v2: a section on coherent axion detection and an appendix added