Oscillations of neutrinos and mesons in quantum field theory

Abstract

This report deals with the quantum field theory of particle oscillations in vacuum. We first review the various controversies regarding quantum-mechanical derivations of the oscillation formula, as well as the different field-theoretical approaches proposed to settle them. We then clear up the contradictions between the existing field-theoretical treatments by a thorough study of the external wave packet model. In particular, we show that the latter includes stationary models as a subcase. In addition, we explicitly compute decoherence terms, which destroy interferences, in order to prove that the coherence length can be increased without bound by more accurate energy measurements. We show that decoherence originates not only in the width and in the separation of wave packets, but also in their spreading through space-time. In this review, we neither assume the relativistic limit nor the stability of oscillating particles, so that the oscillation formula derived with field-theoretical methods can be applied not only to neutrinos but also to neutral K and B mesons. Finally, we discuss oscillations of correlated particles in the same framework.Comment: v2, 124 pages, 10 figures (7 more); updated review of the literature; complete derivation of the oscillation probability at short and large distance; more details on the influence of the spreading of the amplitude on decoherence; submitted to Physics Report

Coherence and Wave Packets in Neutrino Oscillations

“…(4.28), or averaging the probability over the same energy spread, as done in the derivation of Eq. (4.29) 11 . As emphasized in Ref.…”

“…[10] (see also Section 2.5 of Ref. [11]). The argument can be illustrated with the density matrix model of neutrino oscillations presented in Section 4.…”

“…The integral over t of exp[−i(E k (p) − E j (p ′ ))t] yields a δ(E k (p) − E j (p ′ )), which means that "interference occurs only between wave packet components with the same energy" [11] (see Refs. [30,71] for similar results in electron interferometry and kaon oscillations).…”

Oscillations and evolution of a hot and dense gas of flavor neutrinos: A quantum field theory study

“…Neutrino masses and mixing decidedly points to new physics beyond the standard model and profoundly impacts on the physics, astrophysics and cosmology of neutrinos. Neutrino oscillations in matter may provide an explanation of the solar neutrino problem by the resonant conversion of flavor neutrinos in the medium, namely the MSW effect [16,17] (for recent reviews see [1]- [15]). The dynamical aspects of neutrino oscillations in extreme conditions of temperature and density play an important role in Big Bang Nucleosynthesis (BBN) and in the lepton asymmetry in the early Universe [18] (for a recent review see [6]) as well as in the physics of core collapse supernovae and the formation, evolution and cooling of neutron stars [19,20,21].…”

Wave packet description of neutrino oscillation in a progenitor star supernova environment

“…There are two ways of facing the wave packet treatment of neutrino oscillation: using quantum mechanics [16][17][18][19][20] or using quantum field theory [21][22][23][24][25][26][27]. In this article we use the quantum mechanical approach, focusing in a supernova environment.…”