Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
  • Open Access

Dipole-coupled heavy-neutral-lepton explanations of the MiniBooNE excess including constraints from MINERvA data

N. W. Kamp, M. Hostert, A. Schneider, S. Vergani, C. A. Argüelles, J. M. Conrad, M. H. Shaevitz, and M. A. Uchida
Phys. Rev. D 107, 055009 – Published 9 March 2023
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • THE DIPOLE PORTAL
  • SIMULATING NEUTRISSIMOS
  • NEUTRISSIMOS AT MiniBooNE
  • NEUTRISSIMOS AT MINERvA
  • DISCUSSION
  • CONCLUSION
  • ACKNOWLEDGMENTS
  • APPENDICES
    • References

    Abstract

    We revisit models of heavy neutral leptons (neutrissimos) with transition magnetic moments as explanations of the 4.8σ excess of electronlike events at MiniBooNE. We first reexamine the preferred regions in the model parameter space to explain MiniBooNE, considering also potential contributions from oscillations due to an eV-scale sterile neutrino. We then derive constraints on the model using neutrino-electron elastic scattering data from MINERvA. To carry out these analyses, we have developed a detailed Monte Carlo simulation of neutrissimo interactions within the MiniBooNE and MINERvA detectors using the LeptonInjector framework. This simulation allows for a significantly more robust evaluation of the neutrissimo model compared to previous studies in the literature—a necessary step in order to begin making definitive statements about beyond the Standard Model explanations of the MiniBooNE excess. We find that MINERvA rules out a large region of parameter space, but allowed solutions exist at the 2σ confidence level. A dedicated MINERvA analysis would likely be able to probe the entire region of preference of MiniBooNE in this model.

    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    8 More
    • Received 9 July 2022
    • Accepted 15 February 2023

    DOI:https://doi.org/10.1103/PhysRevD.107.055009

    Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

    Published by the American Physical Society

    Physics Subject Headings (PhySH)

    1. Physical Systems
    Heavy neutrinos
    1. Properties
    Magnetic moment
    Particles & Fields

    Authors & Affiliations

    N. W. Kamp1, M. Hostert2,3, A. Schneider1, S. Vergani4, C. A. Argüelles5, J. M. Conrad1, M. H. Shaevitz6, and M. A. Uchida4

    • 1Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
    • 2University of Minnesota, Minneapolis, Minnesota 55455, USA
    • 3Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2J 2W9, Canada
    • 4University of Cambridge, Cambridge CB3 0HE, United Kingdom
    • 5Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
    • 6Department of Physics, Columbia University, New York, New York 10027, USA

    Article Text

    Click to Expand

    References

    Click to Expand
    Issue

    Vol. 107, Iss. 5 — 1 March 2023

    Reuse & Permissions
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      N production from ν upscattering (left) and N decay (right).

      Reuse & Permissions
    • Figure 2
      Figure 2

      (Top) Schematic representation of HNL production via upscattering and the subsequent HNL decay within the MiniBooNE (left) and MINERvA (right) detectors. Detector images have been adapted from Refs. [46, 47]. (Bottom) Example upscattering rates within two of the MINERvA nuclear targets as simulated using LeptonInjector. The coherent enhancement of the upscattering cross sections leads to a larger rate in the high-Z components.

      Reuse & Permissions
    • Figure 3
      Figure 3

      The 2σ and 3σ C.L. preferred regions to explain the MiniBooNE anomaly in mass-coupling parameter space for a dipole-coupled heavy neutral lepton. The pink (green) curves correspond to results from fitting the EνQE (cosθ) distribution. Dipole model fits are performed after subtracting the oscillation component from a global fit to a 3+1 model excluding MiniBooNE data [23]. In general, the energy and angular distributions prefer different regions of parameter space, though overlap exists at the 2σ−3σ level.

      Reuse & Permissions
    • Figure 4
      Figure 4

      The EνQE (top) and cosθ distributions at the example dipole model hypothesis indicated by the black star in Fig. 3. The darker contribution in each stacked histogram corresponds to the dipole model prediction, while the lighter contribution corresponds to the oscillation contribution. The background-subtracted MiniBooNE excess is indicated by the black data points, with solid and dashed error bars indicating statistical and statistical+systematic errors, respectively.

      Reuse & Permissions
    • Figure 5
      Figure 5

      1σ C.L. preferred and 2σ C.L. allowed regions with regard to the MiniBooNE anomaly in mass-coupling parameter space for a dipole-coupled heavy neutral lepton. The pink (green) curves correspond to results from fitting the EνQE (cosθ) distribution. Dipole model fits are performed after subtracting the oscillation component from the combined MiniBooNE+MicroBooNE CCQE-like 3+1 fit [40]. Mild preference for a dipole-coupled heavy neutrino with mN≲100  MeV is found at the 1σ level.

      Reuse & Permissions
    • Figure 6
      Figure 6

      Similar to Fig. 4. The EνQE (top) and cosθ (bottom) distributions at the example dipole model hypothesis indicated by the black star in Fig. 5. The oscillation component comes from the combined MiniBooNE+MicroBooNE CCQE-like 3+1 fit [40].

      Reuse & Permissions
    • Figure 7
      Figure 7

      Similar to Fig. 3, but considering the N→ντγ decay channel. On the left, we show the case with coupling dτN=(mτ/mμ)dμN and on the right we consider dτN=1×10−5  GeV−1 instead. Compared to Fig. 3, preferred regions in the lower HNL mass region move to lower dμN values.

      Reuse & Permissions
    • Figure 8
      Figure 8

      (Top) The predicted Eshθsh2 distribution before detector smearing and signal selection for three choices of model parameters at MINERvA. Bottom) The signal selection efficiency of our analysis cuts, excluding the dE/dx cut, as a function of the HNL mass.

      Reuse & Permissions
    • Figure 9
      Figure 9

      The dE/dX distribution of selected events for the three MINERvA analyses. From top to bottom: LE FHC, ME FHC, and ME RHC. The latter has the largest sensitivity due to the smaller backgrounds. All distributions are shown post-MINERvA tune, except for ME RHC, where it is shown before tuning.

      Reuse & Permissions
    • Figure 10
      Figure 10

      (Left) MINERvA constraints in the dipole parameter space at 95% C.L. Solid lines show our nominal limits assuming a ηbkg=30% Gaussian systematic uncertainty on the background normalization, and dashed ones show the constraints assuming an inflated uncertainty of ηbkg=100% on the background. Regions of preference to explain MiniBooNE in the minimal dipole model are also shown as filled contours at 95% C.L. Right) Contours of constant NNfid, the total number of new-physics photons that convert inside the fiducial volume, overlaid on top of the same parameter space.

      Reuse & Permissions
    • Figure 11
      Figure 11

      Same as Fig. 10 but for the case where HNLs have a larger tau-neutrino dipole following an approximate scaling of UV completions of the operator in Eq. (1), dτN=mτ/mμ×dμN. The HNL is shorter-lived due to the additional decay N→ντγ.

      Reuse & Permissions
    • Figure 12
      Figure 12

      Same as Fig. 10 but for the case where HNLs have a larger and fixed tau-neutrino dipole, dτN=(100  TeV)−1. The HNL is shorter lived due to the additional decay N→ντγ.

      Reuse & Permissions
    • Figure 13
      Figure 13

      Comparison of the different nuclear form factors for C12 commonly used in the literature. The dipole form factor (dashed blue) significantly overestimates the form factor at large values of the momentum exchange Q. In this paper, we use the Fourier-Bessel parametrization (solid green) for nuclei for which nuclear data is available, otherwise, we implement the Fermi-symmetrized (FS) Woods-Saxon parametrization (dotted yellow).

      Reuse & Permissions
    • Figure 14
      Figure 14

      Comparison between helicity-flipping and helicity-conserving cross sections for coherent neutrino upscattering on Carbon (left) and free protons (right) for multiple values of the HNL mass mN.

      Reuse & Permissions
    • Figure 15
      Figure 15

      The ratio between helicity-conserving and helicity-flipping upscattering events on Carbon at MiniBooNE.

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review D

    Reuse & Permissions

    It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

    ×

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×