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Constraints on active-sterile neutrino transition magnetic moments from low-energy electronic recoils at direct detection experiments

M. F. Mustamin, M. Demirci

TL;DR

This work probes active–sterile neutrino transition magnetic moments $μ_{ν_{ℓ4}}$ through upscattering of solar neutrinos on electrons in direct-detection experiments. The authors combine SM neutrino–electron scattering with a sterile dipole portal, deriving a differential cross-section that scales with $|μ_{ν_{ℓ4}}/μ_B|^2$ and depends on the sterile mass $m_4$, then compute the expected event rates using a free-electron approximation, solar fluxes, flavor oscillations, and detector effects. They perform a flavor-aware analysis using PandaX-4T Run0/Run1 and XENONnT data, employing a Poisson $\chi^2$ with nuisance terms to extract 1dof and 2dof limits. The resulting 90% CL bounds reach the $\mathcal{O}(10^{-11})\,μ_B$ level for sub-MeV $m_4$, with XENONnT providing the strongest constraints in many channels and the results offering competitive and complementary coverage relative to accelerator, reactor, and astrophysical bounds.

Abstract

Sterile neutrinos can potentially be produced through neutrino transition magnetic moments in neutrino-electron scattering. In this work, we probe such interactions for sterile neutrinos in the low-mass regime using low-energy electronic recoil data from direct detection experiments. We derive robust constraints on the active-sterile neutrino transition magnetic moments, scrutinizing PandaX-4T and XENONnT recent datasets. Detailed statistical analyses are performed, providing exclusion limits at both one and two degrees of freedom. We demonstrate that, as we can distinguish neutrino flavors, direct detection experiments offer a unique framework for studying all possible neutrino flavors. The obtained limits are in agreement with existing results in the literature and extend the sensitivity to previously unexplored regions of the parameter space.

Constraints on active-sterile neutrino transition magnetic moments from low-energy electronic recoils at direct detection experiments

TL;DR

This work probes active–sterile neutrino transition magnetic moments through upscattering of solar neutrinos on electrons in direct-detection experiments. The authors combine SM neutrino–electron scattering with a sterile dipole portal, deriving a differential cross-section that scales with and depends on the sterile mass , then compute the expected event rates using a free-electron approximation, solar fluxes, flavor oscillations, and detector effects. They perform a flavor-aware analysis using PandaX-4T Run0/Run1 and XENONnT data, employing a Poisson with nuisance terms to extract 1dof and 2dof limits. The resulting 90% CL bounds reach the level for sub-MeV , with XENONnT providing the strongest constraints in many channels and the results offering competitive and complementary coverage relative to accelerator, reactor, and astrophysical bounds.

Abstract

Sterile neutrinos can potentially be produced through neutrino transition magnetic moments in neutrino-electron scattering. In this work, we probe such interactions for sterile neutrinos in the low-mass regime using low-energy electronic recoil data from direct detection experiments. We derive robust constraints on the active-sterile neutrino transition magnetic moments, scrutinizing PandaX-4T and XENONnT recent datasets. Detailed statistical analyses are performed, providing exclusion limits at both one and two degrees of freedom. We demonstrate that, as we can distinguish neutrino flavors, direct detection experiments offer a unique framework for studying all possible neutrino flavors. The obtained limits are in agreement with existing results in the literature and extend the sensitivity to previously unexplored regions of the parameter space.

Paper Structure

This paper contains 11 sections, 14 equations, 10 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Theoretical Framework
  3. E$\nu$ES in the SM
  4. Sterile neutrino dipole portal
  5. Data Analysis Details
  6. Event Rate
  7. $\chi^2$ Function
  8. Results
  9. Expected event spectra
  10. Constraints on the sterile neutrino dipole portal
  11. Conclusions

Figures (10)

  • Figure 1: Representative diagrams for E$\nu$ES in the SM via (a) NC and (b) CC channels.
  • Figure 2: Representative diagram for the up-scattering of $\nu_\ell + e^- \rightarrow \nu_4 + e^-$. The dotted vertex represents the neutrino dipole portal of the active-sterile neutrino transition magnetic moment.
  • Figure 3: Behavior of the minimum neutrino energy with the electron recoil energy for different values of sterile neutrino masses.
  • Figure 4: Predicted electron recoil spectra from E$\nu$ES in the presence of active–sterile transition magnetic moments, compared to the measured data from (a) PandaX-4T Run0, (b) PandaX-4T Run1, and (c) XENONnT. Individual contributions to the E$\nu$ES are shown as filled colored histograms, while their corresponding contributions to the total background are represented by empty, outlined histograms in the same colors.
  • Figure 5: The likelihood profile of the effective active-transition magnetic moment $\mu_{\nu_{\ell 4}}$, obtained from PandaX-4T Run0, PandaX-4T Run1, and XENONnT data, for (a) $m_4=0.01 \text{ MeV}$, (b) $m_4=0.1 \text{ MeV}$, and (c) $m_4=0.3 \text{ MeV}$.
  • ...and 5 more figures