Neutrino Propagation In Matter Research Articles

Complete predictions for high-energy neutrino propagation in matter

We present predictions for the interactions of energetic neutrinos with matter as they propagate through Earth towards large-volume detectors. Our results are based on state-of-the-art calculations of the high-energy neutrino-matter interaction cross-sections, which we have implemented in the HEDIS module of GENIE. In addition to the dominant interaction process, deep inelastic scattering off quarks and gluons, we include the relevant subdominant channels: (in)elastic scattering off the photon field of nucleons, coherent scattering off the photon field of nuclei, as well as the scattering on atomic electrons via the Glashow resonance. Our predictions for the neutrino attenuation rates are provided by a new software package, NuPropEarth. We quantify the dependence of our results on the cross-section model, including nuclear corrections, the incidence angle, and the spectral index, and compare them with other publicly available tools.

Bounds on non-standard interactions of neutrinos from IceCube DeepCore data

New physics in neutrino sector can reveal itself via non-standard neutrino in- teractions which can result in modification of the standard picture of neutrino propagation in matter. Experiments with atmospheric neutrinos has been used to probe this scenario. Using publicly available three-year low energy data in IceCube DeepCore we place bounds on the parameters Eαβ of non-standard neutrino interactions in propagation. We obtain re- strictive constraints not only for μτ sector but also for flavor changing interactions involving electron neutrinos.

Charged lepton flavor change and nonstandard neutrino interactions

Non-Standard neutrino Interactions (NSI) are vector contact interactions involving two neutrinos and two first generation fermions, which can affect neutrino propagation in matter. SU(2) gauge invariance suggests that NSI should be accompanied by more observable charged lepton contact interactions. However, these can be avoided at tree level in various ways. We focus on lepton flavour-changing NSI, suppose they are generated by New Physics heavier than $m_W$ that does not induce (charged) Lepton Flavour Violation (LFV) at tree level, and show that LFV is generated at one loop in most cases. The current constraints on charged Lepton Flavour Violation therefore suggest that mu <---> e flavour-changing NSI are unobservable and tau <---> l flavour-changing NSI are an order of magnitude weaker than the weak interactions. This conclusion can be avoided if the heavy New Physics conspires to cancel the one-loop LFV, or if NSI are generated by light New Physics to which our analysis does not apply.

Simple and precise factorization of the Jarlskog invariant for neutrino oscillations in matter

For neutrino propagation in matter, we show that the Jarlskog invariant, which controls the size of true CP violation in neutrino oscillation appearance experiments, factorizes into three pieces: the vacuum Jarlskog invariant times two simple two-flavor matter resonance factors that control the matter effects for the solar and atmospheric resonances independently. If the solar effective matter potential and the atmospheric effective $\Delta m^2$ are chosen carefully for these two resonance factors, then the fractional corrections to this factorization are an impressive 0.04\% or smaller. We also show that the inverse of the square of the Jarlskog in matter ($1/\hat{J}^2$) is a fourth order polynomial in the matter potential which guarantees that it can be factored into two quadratics which immediately implies the functional form of our approximate, factorized expression.

Exploring new physics from ντ events in OPERA

We analyze in details the impact of the 10 ντ events seen in the OPERA experiment [1] in constraining the Non Standard Interaction parameter εμτ affecting neutrino propagation in matter and the allowed parameter space of models with one sterile neutrino of the 3+1 type.

On the systematic uncertainties in DUNE and their role in New Physics studies

In the recent years experiments have established the existence of neutrino oscillations and most of the oscillation parameters have been measured with a good accuracy. The search for New Physics in neutrino oscillation will be an experimental concrete possibility in the next future. In this paper we investigate the ability of the DUNE facility to search for Non Standard Interaction (NSI) in neutrino propagation in matter, emphasizing the role of different assumptions on the shape and absolute normalization errors of both νe and νμ signals. We also study in detail the effects of NSI and systematics in the extraction of standard oscillation parameters.

Neutrino discovery limit of Dark Matter direct detection experiments in the presence of non-standard interactions

The detection of coherent neutrino-nucleus scattering by the COHERENT collaboration has set on quantitative grounds the existence of an irreducible neutrino background in direct detection searches of Weakly Interacting Massive Dark Matter candidates. This background leads to an ultimate discovery limit for these experiments: a minimum Dark Matter interaction cross section below which events produced by the coherent neutrino scattering will mimic the Dark Matter signal, the so-called neutrino floor. In this work we study the modification of such neutrino floor induced by non-standard neutrino interactions within their presently allowed values by the global analysis of oscillation and COHERENT data. By using the full likelihood information of such global analysis we consistently account for the correlated effects of non-standard neutrino interactions both in the neutrino propagation in matter and in its interaction in the detector. We quantify their impact on the neutrino floor for five future experiments: DARWIN (Xe), ARGO (Ar), Super-CDMS HV (Ge and Si) and CRESST phase III (CaWO4). Quantitatively, we find that non-standard neutrino interactions allowed at the 3σ level can result in an increase of the neutrino floor of up to a factor ∼ 5 with respect to the Standard Model expectations and impact the expected sensitivities of the ARGO, CRESST phase III and DARWIN experiments.

Three neutrino oscillations in matter

Following similar approaches in the past, the Schrödinger equation for three neutrino propagation in matter of constant density is solved analytically by two successive diagonalizations of 2×2 matrices. The final result for the oscillation probabilities is obtained directly in the conventional parametric form as in the vacuum but with explicit simple modification of two mixing angles (θ12 and θ13) and mass eigenvalues. In this form, the analytical results provide excellent approximation to numerical calculations and allow for simple qualitative understanding of the matter effects.

Nonmaximal neutrino mixing at NOνA from nonstandard interactions

Muon neutrino disappearance measurements at NOνA suggest that maximal θ23 is excluded at the 2.6σ CL. This is in mild tension with T2K data which prefer maximal mixing. Considering that NOνA has a much longer baseline than T2K, we point out that the apparent departure from maximal mixing in NOνA may be a consequence of nonstandard neutrino propagation in matter.

Neutrino Propagation in Matter

We describe the effects of neutrino propagation in the matter of the Earth relevant to experiments with atmospheric and accelerator neutrinos and aimed at the determination of the neutrino mass hierarchy and CP violation. These include (i) the resonance enhancement of neutrino oscillations in matter with constant or nearly constant density, (ii) adiabatic conversion in matter with slowly changing density, (iii) parametric enhancement of oscillations in a multilayer medium, and (iv) oscillations in thin layers of matter. We present the results of semianalytic descriptions of flavor transitions for the cases of small density perturbations, in the limit of large densities and for small density widths. Neutrino oscillograms of the Earth and their structure after determination of the 1–3 mixing are described. A possibility to identify the neutrino mass hierarchy with the atmospheric neutrinos and multimegaton scale detectors having low energy thresholds is explored. The potential of future accelerator experiments to establish the hierarchy is outlined.

Erratum: Rephasing invariance and neutrino mixing

A rephasing invariant parametrization is introduced for three flavor neutrino mixing. For neutrino propagation in matter, these parameters are shown to obey evolution equations as functions of the induced neutrino mass. These equations are found to preserve (approximately) some characteristic features of the mixing matrix, resulting in solutions which exhibit striking patterns as the induced mass varies. The approximate solutions are compared to numerical integrations and found to be quite accurate.

Rephasing invariance and neutrino mixing

A rephasing invariant parametrization is introduced for three flavor neutrino mixing. For neutrino propagation in matter, these parameters are shown to obey evolution equations as functions of the induced neutrino mass. These equations are found to preserve (approximately) some characteristic features of the mixing matrix, resulting in solutions which exhibit striking patterns as the induced mass varies. The approximate solutions are compared to numerical integrations and found to be quite accurate.

In situdetermination of Earth matter density in a neutrino factory

We point out that an accurate in situ determination of the earth matter density $\ensuremath{\rho}$ is possible in neutrino factory by placing a detector at the magic baseline, $L=\sqrt{2}\ensuremath{\pi}/{G}_{F}{N}_{e}$ where ${N}_{e}$ denotes electron number density. The accuracy of matter density determination is excellent in a region of relatively large ${\ensuremath{\theta}}_{13}$ with fractional uncertainty $\ensuremath{\delta}\ensuremath{\rho}/\ensuremath{\rho}$ of about 0.43%, 1.3%, and $\ensuremath{\lesssim}3%$ at $1\ensuremath{\sigma}$ CL at ${sin}^{2}2{\ensuremath{\theta}}_{13}=0.1$, ${10}^{\ensuremath{-}2}$, and $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, respectively. At smaller ${\ensuremath{\theta}}_{13}$ the uncertainty depends upon the $CP$ phase $\ensuremath{\delta}$, but it remains small, 3%--7% in more than $3/4$ of the entire region of $\ensuremath{\delta}$ at ${sin}^{2}2{\ensuremath{\theta}}_{13}={10}^{\ensuremath{-}4}$. The results would allow us to solve the problem of obscured $CP$ violation due to the uncertainty of earth matter density in a wide range of ${\ensuremath{\theta}}_{13}$ and $\ensuremath{\delta}$. It may provide a test for the geophysical model of the earth, or it may serve as a method for a stringent test of the Mikheyev-Smirnov-Wolfenstein theory of neutrino propagation in matter once an accurate geophysical estimation of the matter density is available.

Neutrino oscillations in Robertson-Walker space-time with torsion

The scheme proposed by Cardall and Fuller to study neutrino oscillation in curved space-time is applied to the Robertson-Walker space-time with torsion. The radial neutrino oscillation is studied both in vacuum and in regions containing electrons. The influence of the cosmological background on the resonance and on the adiabaticity properties of neutrino oscillations are as well studied and explicitly calculated in case the Standard Cosmological model is assumed. The formalism developed for torsion-free neutrino propagation in matter is extended to describe the effect of torsion on neutrino oscillation in vacuum. As a result, resonance and nonadiabatic propagation seem a priori possible for cosmological neutrino in vacuum with self-interaction produced by torsion.

Neutrino matter effect invariants and the observables of neutrino oscillations

We generalise our previous observation on the invariance of the Jarlskog determinant to matter effects in neutrino oscillations. Within the context of standard neutrino oscillation theory with matter effects, we present the complete set of (five) matter invariant observables for neutrino propagation in matter. We give some examples of their application.

Equations for neutrino propagation in matter

We study the dynamical equations for two-family neutrino oscillations in a medium of continuously varying density. Explicit solutions to these equations take the form of series of nested integrals. These solutions can serve as a basis for numerical calculation of these processes or for further study of their analytical properties.

Neutrino propagation in matter and a CP-violating phase

We point out that the dependence on the order of the matter through which neutrinos pass can provide a window into the presence of a CP-violating phase in the mixing matrix of the neutrino sector. This allows for study of CP in the neutrino sector without the necessity of making a comparison between the behavior of neutrinos and that of antineutrinos.

Neutrino propagation in matter using the wave packet approach

We study the oscillations and conversions of relativistic neutrinos propagating in matter of variable density using the wave packet formalism. We show how the oscillation and coherence lengths are modified in comparison with the case of oscillations in vacuum. Secondly, we demonstrate how the equation of motion for two neutrino flavors can be formally solved for almost arbitrary density profile. We calculate finally how the use of wave packets alters the nonadiabatic level crossing probabilities. For the most common physical environments the corrections due to the width of the wave packet do not lead to observable effects.

Neutrino propagation in matter with general interactions

We present a general analysis of the effective potential for neutrino propagation in matter, assuming a generic set of Lorentz invariant non-derivative interactions. We find that in addition to the known vector and axial vector terms, in a polarized medium also tensor interactions can play an important role. We compute the effective potential arising from a tensor interaction. We show that the components of the tensor potential transverse to the direction of the neutrino propagation can induce a neutrino spin-flip, similar to the one induced by a transverse magnetic field.

Neutrino propagation in matter

The enhancement of neutrino oscillations in matter is briefly reviewed. Exact and approximate solutions of the equations describing neutrino oscillations in matter are discussed. The role of stochasticity of the media that the neutrinos propagate through is elucidated.