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A decoherence explanation of the gallium neutrino anomaly

by Yasaman Farzan, Thomas Schwetz

This Submission thread is now published as

Submission summary

Authors (as registered SciPost users): Thomas Schwetz
Submission information
Preprint Link: scipost_202306_00037v1  (pdf)
Date accepted: 2023-09-22
Date submitted: 2023-06-27 11:16
Submitted by: Schwetz, Thomas
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • High-Energy Physics - Phenomenology
Approach: Phenomenological


Gallium radioactive source experiments have reported a neutrino-induced event rate about 20% lower than expected with a high statistical significance. We present an explanation of this observation assuming quantum decoherence of the neutrinos in the gallium detectors at a scale of 2 m. This explanation is consistent with global data on neutrino oscillations, including solar neutrinos, if decoherence effects decrease quickly with energy, for instance with a power law $E^{-r}$ with r ≈ 12. Our proposal does not require the presence of sterile neutrinos but implies a modification of the standard quantum mechanical evolution equations for active neutrinos.

Published as SciPost Phys. 15, 172 (2023)

Reports on this Submission

Anonymous Report 2 on 2023-9-10 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_202306_00037v1, delivered 2023-09-10, doi: 10.21468/SciPost.Report.7792


Clear presentation
Possibility of testing the proposed explanation


This paper discusses an explanation of the gallium neutrino anomaly
based on decoherence effects. Due to the peculiar energy dependence of the decoherence effect, only low-energy neutrinos relevant to the Gallium experiments are affected, while experiments involving high-energy neutrinos are essentially unmodified. Even if similar decoherence effects have not been observed so far, such an explanation is very economical since it does not require enlarging the particle content of the Standard Model. Future experiments will be able to test the explanation.

I recommend the publication of this paper in its present form.

  • validity: high
  • significance: high
  • originality: high
  • clarity: high
  • formatting: perfect
  • grammar: perfect

Anonymous Report 1 on 2023-9-6 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_202306_00037v1, delivered 2023-09-06, doi: 10.21468/SciPost.Report.7770


This paper presents a decoherence explanation of the gallium neutrino anomaly.

It is assumed that decoherence happens for the low-energy neutrinos in gallium experiments but not for the higher energy neutrinos in other experiments, because of a very steep dependence on energy.

I think that this explanation of the gallium neutrino anomaly is rather ad hoc, but it cannot be excluded.
It is however interesting, because it does not need a sterile neutrino or other non-standard effect beyond the decoherence.
It is also interesting that it can be tested in the future by checking the prediction of a distance-dependent deficit for the radioactive source experiments.

The paper is clear and well-written.

In conclusion, I recommend the publication of this paper.

  • validity: -
  • significance: -
  • originality: -
  • clarity: -
  • formatting: -
  • grammar: -

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