Improved eV-scale Sterile-Neutrino Constraints from the Second KATRIN Measurement Campaign

Abstract

We present the results of the light sterile neutrino search from the second KATRIN measurement campaign in 2019. Approaching nominal activity, $3.76\times 10^6$ tritium $\beta$-electrons are analyzed in an energy window extending down to $40$eV below the tritium endpoint at $E_0=18.57$keV. We consider the $3\nu +1$ framework with three active and one sterile neutrino flavor. The analysis is sensitive to a fourth mass eigenstate $m_4^2\lesssim 1600$eV${}^2$ and active-to-sterile mixing $|U_{e4}{|}^2\gtrsim 6\times 10^{-3}$. As no sterile-neutrino signal was observed, we provide improved exclusion contours on $m_4^2$ and $|U_{e4}{|}^2$ at $95$% C.L. Our results supersede the limits from the Mainz and Troitsk experiments. Furthermore, we are able to exclude the large $\Delta m_{41}^2$ solutions of the reactor antineutrino and gallium anomalies to a great extent. The latter has recently been reaffirmed by the BEST collaboration and could be explained by a sterile neutrino with large mixing. While the remaining solutions at small $\Delta m_{41}^2$ are mostly excluded by short-baseline reactor experiments, KATRIN is the only ongoing laboratory experiment to be sensitive to relevant solutions at large $\Delta m_{41}^2$ through a robust spectral shape analysis.

arXiv comment14 pages, 8 figures, 2 tables

References in corpus (27)

• Evidence for Neutrino Oscillations from the Observation of Electron Anti-neutrinos in a Muon Anti-Neutrino Beam
• The Reactor Antineutrino Anomaly
• Precision Electroweak Measurements on the Z Resonance
• Search for Majorana Neutrinos near the Inverted Mass Hierarchy Region with KamLAND-Zen
• Measurement of the solar neutrino capture rate with gallium metal. III: Results for the 2002--2007 data-taking period
• An improved upper limit on the neutrino mass from a direct kinematic method by KATRIN
• Significant Excess of ElectronLike Events in the MiniBooNE Short-Baseline Neutrino Experiment
• Final Results of GERDA on the Search for Neutrinoless Double-$\beta$ Decay
• Testing the statistical compatibility of independent data sets
• Improved Short-Baseline Neutrino Oscillation Search and Energy Spectrum Measurement with the PROSPECT Experiment at HFIR
• Improved Sterile Neutrino Constraints from the STEREO Experiment with 179 Days of Reactor-On Data
• The Design, Construction, and Commissioning of the KATRIN Experiment
• Focal-plane detector system for the KATRIN experiment
• A novel detector system for KATRIN to search for keV-scale sterile neutrinos
• Limit on sterile neutrino contribution from the Mainz Neutrino Mass Experiment
• Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments
• Detecting sterile neutrinos with KATRIN like experiments
• Analysis methods for the first KATRIN neutrino-mass measurement
• $\beta$-Decay Spectrum, Response Function and Statistical Model for Neutrino Mass Measurements with the KATRIN Experiment
• Bound on 3+1 active-sterile neutrino mixing from the first four-week science run of KATRIN
• An upper limit on additional neutrino mass eigenstate in 2 to 100 eV region from "Troitsk nu-mass" data
• The KATRIN Superconducting Magnets: Overview and First Performance Results
• KATRIN bound on 3+1 active-sterile neutrino mixing and the reactor antineutrino anomaly
• Neutral tritium gas reduction in the KATRIN differential pumping sections
• Statistical Methods Applied to the Search of Sterile Neutrinos
• Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment
• Search for Signatures of Sterile Neutrinos with Double Chooz

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• Search for Light Sterile Neutrinos With Two Neutrino Beams at MicroBooNE
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• A thermionic electron gun to characterize silicon drift detectors with electrons
• Probing sterile neutrino dark matter in the PTOLEMY-like experiment
• First constraints on general neutrino interactions based on KATRIN data
• Searches for beyond-standard-model physics with astroparticle physics instruments
• Information divergences to parametrize astrophysical uncertainties in dark matter direct detection
• Restricting Sterile Neutrinos by Neutrinoless Double Beta Decay