Decoherence effects in reactor and Gallium neutrino oscillation experiments: a QFT approach

Abstract

We adopt the quantum field theoretical method to calculate the amplitude and event rate for a neutrino oscillation experiment, considering neutrino production, propagation and detection as a single process. This method allows to take into account decoherence effects in the transition amplitude induced by the quantum mechanical uncertainties of all particles involved in the process. We extend the method to include coherence loss due to interactions with the environment, similar to collisional line broadening. In addition to generic decoherence induced at the amplitude level, the formalism allows to include, in a straightforward way, additional damping effects related to phase-space integrals over momenta of unobserved particles as well as other classical averaging effects. We apply this method to neutrino oscillation searches at reactor and Gallium experiments and confirm that quantum decoherence is many orders of magnitudes smaller than classical averaging effects and therefore unobservable. The method used here can be applied with minimal modifications also to other types of oscillation experiments, e.g., accelerator based beam experiments.

A decoherence explanation of the gallium neutrino anomaly

“…[37,38]. Let us stress that the decoherence that we postulate here requires exotic new physics which modifies the standard quantum mechanical evolution; conventional decoherence based on particle localisation leads only to tiny effects which are negligible for all oscillation experiments considered here [39,40].…”

Quantum transport theory for neutrinos with flavor and particle-antiparticle mixing

“…In the QM treatment [1][2][3][4][5][6][7][8][9][10][11] neutrinos are described by wave packets whose widths are related to the uncertainty of neutrino momentum at the production process. In the partial QFT approaches [11][12][13][14][15][16][17][18][19][20][21][22][23] neutrino production, detection and propagation are considered via compound Feynman diagrams that treat neutrinos internally as QFT propagators and externally as wave packets. In vacuum, when decoherence effects related to neutrino production, detection and propagation can be neglected, both approaches lead to the standard formula for neutrino oscillations probabilities.…”