Assessment of molecular effects on neutrino mass measurements from tritium beta decay

Abstract

The beta decay of molecular tritium currently provides the highest sensitivity in laboratory-based neutrino mass measurements. The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will improve the sensitivity to 0.2 eV, making a percent-level quantitative understanding of molecular effects essential. The modern theoretical calculations available for neutrino-mass experiments agree with spectroscopic data. Moreover, when neutrino-mass experiments performed in the 1980s with gaseous tritium are re-evaluated using these modern calculations, the extracted neutrino mass-squared values are consistent with zero instead of being significantly negative. On the other hand, the calculated molecular final-state branching ratios are in tension with dissociation experiments performed in the 1950s. We re-examine the theory of the final-state spectrum of molecular tritium decay and its effect on the determination of the neutrino mass, with an emphasis on the role of the vibrational- and rotational-state distribution in the ground electronic state. General features can be reproduced quantitatively from considerations of kinematics and zero-point motion. We summarize the status of validation efforts and suggest means for resolving the apparent discrepancy in dissociation rates.

References in corpus (6)

• Big-Bang Nucleosynthesis
• Neutrino cosmology and Planck
• Sensitivity of Next-Generation Tritium Beta-Decay Experiments for keV-Scale Sterile Neutrinos
• Precision high voltage divider for the KATRIN experiment
• Exact relativistic beta decay endpoint spectrum
• Exact relativistic tritium beta-decay endpoint spectrum in a hadron model

Cited by in corpus (18)

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• Effective neutrino masses in KATRIN and future tritium beta-decay experiments
• Cyclotron Radiation Emission Spectroscopy of Electrons from Tritium Beta Decay and ${}^{83\mathrm{m}}$Kr Internal Conversion
• Quantum Induced Broadening- A Challenge For Cosmic Neutrino Background Discovery
• Determining Absolute Neutrino Mass using Quantum Technologies
• CARS spectroscopy of the ($v=0\to 1$) band in ${\mathrm{T}}_2$
• SYNCA: A Synthetic Cyclotron Antenna for the Project 8 Collaboration
• Demonstration of tritium adsorption on graphene
• Shake-up and shake-off effects in neutrinoless double-beta decay
• A study of the relativistic corrections to polarized tritium $\beta$-decay
• Status and Perspectives of Neutrino Physics
• Monte Carlo simulations of the electron-gas interactions in the KATRIN experiment
• New Constraint on the Local Relic Neutrino Background Overdensity with the First KATRIN Data Runs