Neutrino Oscillations, Entanglement and Coherence: A Quantum Field Theory Study in Real Time

Abstract

The dynamics of neutrino mixing and oscillations are studied directly in finite real time in a model that effectively describes charged current weak interactions. Finite time corrections to the S-matrix result for the appearance and disappearance probabilities are obtained. It is observed that these effects may be of the same order of the S-matrix result in long-baseline appearance experiments. We argue that fundamentally, the S-matrix is ill-suited to describe long-baseline events due to the fact that the neutrino is produced in an entangled state with the charged lepton, which can be disentangled by the measurement of the charged lepton near the production site. The appearance and disappearance far-detection process is described from the time evolution of this disentangled "collapsed" state, allowing us to establish the conditions under which factorization of detection rates emerges in long-baseline experiments. We also study the time evolution of the reduced density matrix and show explicitly how oscillations are manifest in the off-diagonal terms, i.e., coherences, as a result of a finite time analysis. Lastly, we study a model for the "GSI anomaly" obtaining the time evolution of the population of parent and daughter particles directly in real time. We confirm that the decay rate of parent and growth rate December 3, 2018 12:39 WSPC/INSTRUCTION FILE nuoscillation-IJMPA-revised of daughters do not feature oscillatory behavior from interference of mass eigenstates.

Approximate neutrino oscillations in the vacuum

“…Second, a neutrino may travel from the detector to the source. If we let the masses M I H of the H particles be more massive than those M I L of the L particles, where I runs over {S, D} then the second process will be far off shell and will have a negligible contribution for macroscopic baselines [19]. Therefore we will consider only the contribution from the first process.…”

“…[17] and also the relevance of the finite time nature of such experiments which may in principle invalidate an Smatrix treatment as was claimed in Ref. [19], one may also not trust the results of the external wave packet model. Motivated by these concerns, in Sect.…”

Unsterile-Active Neutrino Mixing

“…The complications that come from the momentum-dependent mixing angles and non-trivial spectral densities render a full quantum field theoretical treatment of this model necessary. A work studying the activeactive neutrino oscillations dynamics in the 2 +1 scheme using the real time quantum field theoretical formalism as introduced in [9], in particular Section IV, is in progress. Perhaps the results will lead to the reconciliation of the LSND and MiniBooNE results.…”

Approximate Neutrino Oscillations in the Vacuum

“…Given the relevance of entanglement between the source and the neutrino to oscillation physics which has been highlighted in Ref. [13] and also the relevance of the finite time nature of such experiments which may in principle invalidate an S-matrix treatment as was claimed in Ref [14], one may also not trust the results of the external wave packet model. Motivated by these concerns, in Sec.…”