Unitarity and the three flavour neutrino mixing matrix

Abstract

Unitarity is a fundamental property of any theory required to ensure we work in a theoretically consistent framework. In comparison with the quark sector, experimental tests of unitarity for the 3x3 neutrino mixing matrix are considerably weaker. It must be remembered that the vast majority of our information on the neutrino mixing angles originates from ${\overline{\nu }}_e$ and ${\nu }_{\mu }$ disappearance experiments, with the assumption of unitarity being invoked to constrain the remaining elements. New physics can invalidate this assumption for the 3x3 subset and thus modify our precision measurements. We perform a reanalysis to see how global knowledge is altered when one refits oscillation results without assuming unitarity, and present $3\sigma$ ranges for allowed $U_{\text{PMNS}}$ elements consistent with all observed phenomena. We calculate the bounds on the closure of the six neutrino unitarity triangles, with the closure of the ${\nu }_e{\nu }_{\mu }$ triangle being constrained to be $\le$ 0.03, while the remaining triangles are significantly less constrained to be $\le$ 0.1 - 0.2. Similarly for the row and column normalization, we find their deviation from unity is constrained to be $\le$ 0.2 - 0.4, for four out of six such normalisations, while for the ${\nu }_{\mu }$ and ${\nu }_e$ row normalisation the deviations are constrained to be $\le$ 0.07, all at the $3\sigma$ CL. We emphasise that there is significant room for new low energy physics, especially in the ${\nu }_{\tau }$ sector which very few current experiments constrain directly.

8 pages, 3 figures and 1 table

References in corpus (15)

• Observation of electron-antineutrino disappearance at Daya Bay
• The Reactor Antineutrino Anomaly
• Updated fit to three neutrino mixing: status of leptonic CP violation
• Neutrino oscillations refitted
• Improved Measurement of Electron Antineutrino Disappearance at Daya Bay
• Unitarity of the Leptonic Mixing Matrix
• A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
• Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6E20 protons on target
• Non-unitarity of the leptonic mixing matrix: Present bounds and future sensitivities
• Discovery of tau neutrino appearance in the CNGS neutrino beam with the OPERA experiment
• Limits on sterile neutrino mixing using atmospheric neutrinos in Super-Kamiokande
• On the description of non-unitary neutrino mixing
• Search for a Light Sterile Neutrino at Daya Bay
• Dual baseline search for muon antineutrino disappearance at 0.1 eV^2 < Δm^2 < 100 eV^2
• Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Cited by in corpus (79)

• IceCube-Gen2: The Window to the Extreme Universe
• Global constraints on heavy neutrino mixing
• Non-Unitarity, sterile neutrinos, and Non-Standard neutrino Interactions
• Current unknowns in the three neutrino framework
• The Present and Future Status of Heavy Neutral Leptons
• Search for sterile neutrinos in MINOS and MINOS+ using a two-detector fit
• Status of Light Sterile Neutrino Searches
• Prospects for Beyond the Standard Model Physics Searches at the Deep Underground Neutrino Experiment
• Measurement of Atmospheric Tau Neutrino Appearance with IceCube DeepCore
• Sub-percent Precision Measurement of Neutrino Oscillation Parameters with JUNO
• White Paper on New Opportunities at the Next-Generation Neutrino Experiments (Part 1: BSM Neutrino Physics and Dark Matter)
• First Constraints on the Complete Neutrino Mixing Matrix with a Sterile Neutrino
• Probing CP violation with non-unitary mixing in long-baseline neutrino oscillation experiments: DUNE as a case study
• Testing New Physics Explanations of MiniBooNE Anomaly at Neutrino Scattering Experiments
• Physics with Beam Tau-Neutrino Appearance at DUNE
• GeV-scale neutrinos: interactions with mesons and DUNE sensitivity
• PINGU: A Vision for Neutrino and Particle Physics at the South Pole
• Searching for eV-scale sterile neutrinos with eight years of atmospheric neutrinos at the IceCube neutrino telescope
• The Future of High-Energy Astrophysical Neutrino Flavor Measurements
• Snowmass White Paper: Beyond the Standard Model effects on Neutrino Flavor
• Astrophysical neutrinos flavored with Beyond the Standard Model physics
• A realistic model for Dark Matter interactions in the neutrino portal paradigm
• Neutrinos in Large Extra Dimensions and Short-Baseline ${\nu }_e$ Appearance
• Tau Neutrinos in the Next Decade: from GeV to EeV
• A framework for testing leptonic unitarity by neutrino oscillation experiments
• Current and Future Neutrino Oscillation Constraints on Leptonic Unitarity
• Non-unitary neutrino mixing in short and long-baseline experiments
• DUNE sensitivities to the mixing between sterile and tau neutrinos
• Ultralight Fermionic Dark Matter
• Tau neutrinos at DUNE: new strategies, new opportunities
• Majorana Neutrinos in Same-Sign $W^{\pm }{W}^{\pm }$ Scattering at the LHC: Breaking the TeV Barrier
• Vector Boson Scattering Processes: Status and Prospects
• Favoured $B_c$ Decay modes to search for a Majorana neutrino
• Sterile Neutrino Searches with MicroBooNE: Electron Neutrino Disappearance
• Searches for new physics at the Hyper-Kamiokande experiment
• Can we probe intrinsic CP/T violation and non-unitarity at long baseline accelerator experiments?
• An Andean Deep-Valley Detector for High-Energy Tau Neutrinos
• Probing Direct and Indirect Unitarity Violation in Future Accelerator Neutrino Facilities
• Leptonic Unitarity Triangles
• Global oscillation data analysis on the $3\nu$ mixing without unitarity
• Probe Of Sterile Neutrinos Using Astrophysical Neutrino Flavor
• New oscillation and scattering constraints on the tau row matrix elements without assuming unitarity
• Model-Independent Constraints on Non-Unitary Neutrino Mixing from High-Precision Long-Baseline Experiments
• Indirect unitarity violation entangled with matter effects in reactor antineutrino oscillations
• Towards Resolving the Gallium Anomaly
• Neutrino Constraints and the ATOMKI X17 Anomaly
• Prospects of Light Sterile Neutrino Oscillation and CP Violation Searches at the Fermilab Short Baseline Neutrino Facility
• GRB 221009A Gamma Rays from Radiative Decay of Heavy Neutrinos?
• MiniBooNE and MicroBooNE Combined Fit to a 3+1 Sterile Neutrino Scenario
• Standard versus Non-Standard CP Phases in Neutrino Oscillation in Matter with Non-Unitarity
• Reactor antineutrino flux and anomaly
• New limits on neutrino non-standard mixings based on prescribed singular values
• Here Comes the Sun: Solar Parameters in Long-Baseline Accelerator Neutrino Oscillations
• Tau Neutrino Identification in Atmospheric Neutrino Oscillations Without Particle Identification or Unitarity
• Discriminating sterile neutrinos and unitarity violation with CP invariants
• Neutrino mixing, interval matrices and singular values
• Non-Unitarity at DUNE and T2HK with Charged and Neutral Current Measurements
• Measuring tau neutrino appearance probability via unitarity
• Dual-Baseline Search for Active-to-Sterile Neutrino Oscillations in NOvA
• Neutrino Tagging, a new tool for accelerator based neutrino experiments
• New mixing schemes for (3+1) neutrinos
• Constraints on non-unitary neutrino mixing in light of atmospheric and reactor neutrino data
• Towards a Sub-percent Precision Measurement of ${\sin }^2{\theta }_{13}$ with Reactor Antineutrinos
• Toward diagnosing neutrino non-unitarity through CP phase correlations
• Search for Hidden Neutrinos at the European Spallation Source: the SHiNESS experiment
• From ray to spray: augmenting amplitudes and taming fast oscillations in fully numerical neutrino codes
• Testing unitarity of the $3\times 3$ neutrino mixing matrix in an atomic system
• MeV Sterile Neutrino in light of the Cabibbo-Angle Anomaly
• Dark Matter and Neutrino Masses in a Portalino-like Model
• Analytic Neutrino Oscillation Probabilities
• Light sterile neutrino and leptogenesis
• Symmetry in neutrino oscillation in matter with non-unitarity
• New parameter region in sterile neutrino searches: a scenario to alleviate cosmological neutrino mass bound and its testability at oscillation experiments
• Signals of eV-scale sterile neutrino at long baseline neutrino experiments
• Status and Perspectives of Neutrino Physics
• New physics from oscillations at the DUNE near detector, and the role of systematic uncertainties
• Search for active-sterile antineutrino mixing using neutral-current interactions with the NOvA experiment
• Matter neutrino oscillations, an approximation in a parametrization-free framework
• Impact of unitarity violation on sensitivity of the leptonic CP phase at Hyper-Kamiokande and DUNE