Search results for " Oscillation"

Unveiling ν secrets with cosmological data: Neutrino masses and mass hierarchy

2017

Using some of the latest cosmological datasets publicly available, we derive the strongest bounds in the literature on the sum of the three active neutrino masses, $M_\nu$, within the assumption of a background flat $\Lambda$CDM cosmology. In the most conservative scheme, combining Planck cosmic microwave background (CMB) temperature anisotropies and baryon acoustic oscillations (BAO) data, as well as the up-to-date constraint on the optical depth to reionization ($\tau$), the tightest $95\%$ confidence level (C.L.) upper bound we find is $M_\nu0.06\,{\rm eV}$ from oscillations data would raise the quoted upper bounds by ${\cal O}(0.1\sigma)$ and would not affect our conclusions.

Testing generalized CP symmetries with precision studies at DUNE

2019

We examine the capabilities of the DUNE experiment in probing leptonic CP violation within the framework of theories with generalized CP symmetries characterized by the texture zeros of the corresponding CP transformation matrices. We investigate DUNE's potential to probe the two least known oscillation parameters, the atmospheric mixing angle $\theta_{23}$ and the Dirac CP-phase $\delta_{\rm CP}$. We fix theory-motivated benchmarks for ($ \sin^2\theta_{23}, \delta_{\rm CP} $) and take them as true values in our simulations. Assuming 3.5 years of neutrino running plus 3.5 years in the antineutrino mode, we show that in all cases DUNE can significantly constrain and in certain cases rule out…

Progress and open questions in the physics of neutrino cross sections at intermediate energies

2014

New and more precise measurements of neutrino cross sections have renewed the interest in a better understanding of electroweak interactions on nucleons and nuclei. This effort is crucial to achieve the precision goals of the neutrino oscillation program, making new discoveries, like the CP violation in the leptonic sector, possible. We review the recent progress in the physics of neutrino cross sections, putting emphasis on the open questions that arise in the comparison with new experimental data. Following an overview of recent neutrino experiments and future plans, we present some details about the theoretical development in the description of (anti)neutrino-induced quasielastic scatter…

Resolving the atmospheric octant by an improved measurement of the reactor angle

2017

Taking into account the current global information on neutrino oscillation parameters we forecast the capabilities of future long baseline experiments such as DUNE and T2HK in settling the atmospheric octant puzzle. We find that a good measurement of the reactor angle $\theta_{13}$ plays a key role in fixing the octant of the atmospheric angle $\theta_{23}$ with such future accelerator neutrino studies.

Quasi-Dirac neutrino oscillations at DUNE and JUNO

2019

Quasi-Dirac neutrinos are obtained when the Lagrangian density of a neutrino mass model contains both Dirac and Majorana mass terms, and the Majorana terms are sufficiently small. This type of neutrinos introduces new mixing angles and mass splittings into the Hamiltonian, which will modify the standard neutrino oscillation probabilities. In this paper, we focus on the case where the new mass splittings are too small to be measured, but new angles and phases are present. We perform a sensitivity study for this scenario for the upcoming experiments DUNE and JUNO, finding that they will improve current bounds on the relevant parameters. Finally, we also explore the discovery potential of both…

Neutrino oscillations from warped flavor symmetry: predictions for long baseline experiments T2K, NOvA and DUNE

2016

Here we study the pattern of neutrino oscillations emerging from a previously proposed warped model construction incorporating $\Delta(27)$ flavor symmetry. In addition to a complete description of fermion masses, the model predicts the lepton mixing matrix in terms of two parameters. The good measurement of $\theta_{13}$ makes these two parameters nearly proportional, leading to an approximate one-parameter description of neutrino oscillations. There is a sharp fourfold degenerate correlation between $\delta_{CP}$ and the atmospheric mixing angle $\theta_{23}$, so that maximal $\theta_{23}$ also implies maximal leptonic CP violation. The predicted electron neutrino and anti-neutrino appear…

2017

The T2K experiment reports an updated analysis of neutrino and antineutrino oscillations in appearance and disappearance channels. A sample of electron neutrino candidates at Super-Kamiokande in which a pion decay has been tagged is added to the four single-ring samples used in previous T2K oscillation analyses. Through combined analyses of these five samples, simultaneous measurements of four oscillation parameters, |Δm322|, sin2θ23, sin2θ13, and δCP and of the mass ordering are made. A set of studies of simulated data indicates that the sensitivity to the oscillation parameters is not limited by neutrino interaction model uncertainty. Multiple oscillation analyses are performed, and frequ…

Realistic Tri-Bi-Maximal neutrino mixing

2018

We propose a generalized version of the Tri-Bi-Maximal (TBM) ansatz for lepton mixing, leading to non-zero reactor angle $\theta_{13}$ and CP violation. The latter is characterized by two CP phases. The Dirac phase affecting neutrino oscillations is nearly maximal ($\delta_{CP} \sim \pm \pi/2$), while the Majorana phase implies narrow allowed ranges for the neutrinoless double beta decay amplitude. The solar angle $\theta_{12}$ lies nearly at its TBM value, while the atmospheric angle $\theta_{23}$ has the TBM value for maximal $\delta_{CP}$. Neutrino oscillation predictions can be tested in present and upcoming experiments.

Classifying CP transformations according to their texture zeros: theory and implications

2016

We provide a classification of generalized CP symmetries preserved by the neutrino mass matrix according to the number of zero entries in the associated transformation matrix. We determine the corresponding constrained form of the lepton mixing matrix, characterized by correlations between the mixing angles and the CP violating phases. We compare with the corresponding restrictions from current neutrino oscillation global fits and show that, in some cases, the Dirac CP phase characterizing oscillations is highly constrained. Implications for current and upcoming long baseline neutrino oscillation experiments T2K, NO$\nu$A and DUNE, as well as neutrinoless double beta decay experiments are d…

Rare Z Decays and Neutrino Flavor Universality

2015

We study rare four-body decays of the Z-boson involving at least one neutrino and one charged lepton. Large destructive interferences make these decays very sensitive to the Z couplings to neutrinos. As the identified charged leptons can determine the neutrino flavors, these decays probe the universality of the Z couplings to neutrinos. The rare four-body processes could be accurately measured at future lepton colliders, leading to percent level precision.