The Phase of Neutrino Oscillations

2021

Neutrinos are one of the most elusive of the Standard Model particles known to physicists today. Despite the fact that crucial characteristics of these leptons remain largely a mystery, studying them can hold the key to fundamental insights for the field of particle physics and for our understanding of the universe as a whole. In order to learn why there is so much discussion within the physics community about these mysterious particles, its important to start at the beginning and connect one of their most important characteristics that of oscillations between their types with the subject of quantum mechanics. In fact, to engage with the subject of neutrino physics in general, beyond the surface-level qualitative approach, requires the quantum mechanical framework based heavily in linear algebra. Therefore, this paper will give an introduction to neutrino physics, specifically to their oscillations, through connecting the quantum mechanical formalism to current research within this ...

Physics Letters B, 1998

In order to investigate when neutrinos cease to oscillate in the framework of quantum field theory, we have reexamined the wave packet treatment of neutrino oscillations by taking different sizes of the wave packets of the particles involved in the production and detection processes. The treatment is shown to be considerably simplified by using the Grimus-Stockinger theorem which enables us to carry out the integration over the momentum of the propagating neutrino. Our new results confirm the recent observation by Kiers, Nussinov and Weiss that a precise measurement of the energies of the particles involved in the detection process would increase the coherence length. We also present a precise definition of the coherence length beyond which neutrinos cease to oscillate.

2004

We present a derivation of the flavor neutrino states which describe neutrinos produced or detected in charged-current weak-interaction processes, including those operating in neutrino oscillation experiments. We also present a covariant derivation of the probability of neutrino oscillations which is consistent with the fact that flavor is Lorentz-invariant. Finally, we clarify the negative answers to three commonly asked questions: "Do charged leptons oscillate?"; "Is the standard phase wrong by a factor of 2?" "Are flavor neutrinos described by Fock states?".

Arxiv preprint arXiv:0810.4132, 2008

We present an expression for the transition probability between Dirac or Majorana neutrino flavors obtained from first principles within quantum field theory. Our derivation is based on a standard quantum mechanical setup and includes the specific mechanism of neutrino production only in as much as it specifies the initial state. Our expression for the transition probability reproduces the usual formula in the plane wave limit and shows the correct non-relativistic and ultra-relativistic behaviors. It also allows a simple understanding of the decoherence of the oscillations and of the question of the arrival times of the different neutrino mass eigenstates. We show numerical examples for the case of two neutrino generations.

The European Physical Journal C

Quantum correlations provide a fertile testing ground for investigating fundamental aspects of quantum physics in various systems, especially in the case of relativistic (elementary) particle systems as neutrinos. In a recent paper, Ming et al. (Eur Phys J C 80:275, 2020), in connection with results of Daya-Bay and MINOS experiments, have studied the quantumness in neutrino oscillations in the framework of plane-wave approximation. We extend their treatment by adopting the wave packet approach that accounts for effects due to localization and decoherence. This leads to a better agreement with experimental results, in particular for the case of MINOS experiment.

Nuclear Physics B - Proceedings Supplements, 2011

Description of neutrino oscillation in the case of Non-Standard neutrino Interaction (NSI) is briefly presented. The NSI causes the entanglement between internal degrees of freedom of neutrinos (mass, spin, flavour) and other accompanying particles in the production and detection processes. In such case neutrinos are mostly in the mixed states. Role of the density matrix in description of neutrino oscillation process is shortly explained.

Pramana, 2006

We discuss effects of new physics (NP) in neutrino oscillation experiments. Such effects can modify a production neutrino flux, a detection cross-section and a matter transition. As a result, the NP effects change neutrino oscillations both in vacuum and in matter. A relation between the small effects of NP and the oscillation parameters is discussed. It is shown for which parameters the NP effects are suppressed and when they are potentially large. Oscillations of non-unitary mixed neutrinos are presented in more details.

Physical Review D, 1993

We discuss neutrino oscillations in the framework of the quantum field theory without introducing the concept of neutrino weak eigenstates. The external particles are described by wave packets and the different mass eigenstate neutrinos propagate between the production and detection interactions, which are macroscopically localized in space-time. The time-averaged cross section, which is the measurable quantity in the usual experimental setting, is calculated. It is shown that only in the extremely relativistic limit the usual quantum mechanical oscillation probability can be factored out of the cross section.

Pramana, 2000

A brief introduction to the phenomena of vacuum neutrino oscillations and resonant flavour conversion is presented with a heavy pedagogic leaning. Variants of these ideas, e.g., neutrino helicity flip in a magnetic field, violation of the equivalence principle, etc. are outlined. A few vexing issues pertaining to the quantum mechanics of neutrino oscillations are discussed. Expectations from some of the future experiments are summarized.

Physics Letters B, 2019

We study the total and the geometric phase associated with neutrino mixing and we show that the phases produced by the neutrino oscillations have different values depending on the representation of the mixing matrix and on the neutrino nature. Therefore the phases represent a possible probe to distinguish between Dirac and Majorana neutrinos.

1998

The European Physical Journal Plus, 2021

Although the dynamics of the mesonic system is also driven by weak interactions, owing to its short lifetime, this system would be more suitable for understanding foundational issues rather than having any applicational implications.

2006

I summarize the status of neutrino oscillations that follow from current data, including the status of the small parameters ratio of solar-over-atmospheric splitting and $\sin^2\theta_{13}$ characterizing the strength of CP violation in neutrino oscillations. I briefly discuss the impact of oscillation data on the prospects for probing the absolute scale of neutrino mass in neutrinoless double beta decay. I also comment on the theoretical origin of neutrino mass, mentioning recent attemps to explain current data from first principles.

The State of the Art of Neutrino Physics

The recent wide recognition of the existence of neutrino oscillations concludes the pioneer stage of these studies and poses the problem of how to communicate effectively the basic aspects of this branch of science. In fact, the phenomenon of neutrino oscillations has peculiar features and requires to master some specific idea and some amount of formalism. The main aim of these introductory notes is exactly to cover these aspects, in order to allow the interested students to appreciate the modern developments and possibly to begin to do research in neutrino oscillations. iii Preface The structure of these notes is the following. In the first section, we describe the context of the discussion. Then we will introduce the concept of neutrino mixing and analyze its implications. Next, we will examine the basic formalism of neutrino oscillations, recalling a few interesting applications. Subsequently, we discuss the modifications to neutrino oscillations that occur when these particles propagate in the matter. Finally, we offer a brief summary of the results and outline the perspectives. Several appendices supplement the discussion and collect various technical details. We strive to describe all relevant details of the calculations, in order to allow the Reader to understand thoroughly and to appreciate the physics of neutrino oscillation. Instead, we do not aim to achieve completeness and/or to collect the most recent results. We limit the reference list to a minimum: We cite the seminal papers of this field in the next section, mention some few books and review papers in the last section, and occasionally make reference to certain works that are needed to learn more or on which we relied to some large extent for an aspect or another. These choices are dictated not only by the existence of a huge amount of research work on neutrinos, but also and most simply in view of the introductory character of these notes. We assume that the Reader knows special relativity and quantum mechanics, and some basic aspects of particle physics. As a rule we will adopt the system of "natural units" of particle physics, defined by the choices = c = 1 In the equations, the repeated indices are summed, whenever this is not reason of confusion. Our metric is defined by xp = x µ p µ = x 0 p 0 − x • p where x = (x 0 , x) and p = (p 0 , p) are two quadrivectors. Unless stated otherwise, we will use the Dirac (or non-relativistic) representation of the Dirac matrices; see the appendices for technical details.

Thinking, Observing and Mining the Universe, 2004

We review the status of the neutrino oscillations physics, with a particular emphasis on the present knowledge of the neutrino mass-mixing parameters. We consider first the ν µ → ν τ flavor transitions of atmospheric neutrinos. It is found that standard oscillations provide the best description of the SK+K2K data, and that the associated mass-mixing parameters are determined at ±1σ (and N DF = 1) as: ∆m 2 = (2.6 ± 0.4) × 10 −3 eV 2 and sin 2 2θ = 1.00 +0.00 −0.05 . Such indications, presently dominated by SK, could be strengthened by further K2K data. Then we point out that the recent data from the Sudbury Neutrino Observatory, together with other relevant measurements from solar and reactor neutrino experiments, in particular the KamLAND data, convincingly show that the flavor transitions of solar neutrinos are affected by Mikheyev-Smirnov-Wolfenstein (MSW) effects. Finally, we perform an updated analysis of two-family active oscillations of solar and reactor neutrinos in the standard MSW case. * Speaker.