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Cosmic Structure Strikes Back: The Elimination of Vector-Mediated Nonstandard Interaction Models as a Mechanism for Sterile Neutrino Dark Matter Production

Cannon M. Vogel, Helena García Escudero, Kevork N. Abazajian

Abstract

We revisit sterile-neutrino production enabled by nonstandard interactions (NSI) among active neutrinos mediated by new bosons. We focus on vector mediators, including neutrinophilic, gauged $L_μ\!-\!L_τ$, and $B\!-\!L$ realizations that modify in-medium dispersion and scattering, thereby altering the active-sterile conversion history. Building on a novel production framework with NSI thermal potentials and collision integrals, we compute nonthermal phase-space distributions across sterile neutrino mixing and NSI parameters and map each point to an equivalent thermal warm dark matter particle mass $m_\mathrm{th}$ via linear-theory transfer function fitting with cosmological structure-formation Boltzmann solver. This enables a direct reinterpretation of state-of-the-art structure-formation limits from Milky Way satellites, strong lensing, and the Lyman-$α$ forest. These limits, in conjunction with X-ray decay searches, as well as results from a wide variety of particle physics experiments allow for a more complete examination of these models. We find that these vector-mediated models are ruled out when the full combination of current constraints, listed above, are taken into account. NSI scalar-mediated models and models with low-reheating temperatures remain viable.

Cosmic Structure Strikes Back: The Elimination of Vector-Mediated Nonstandard Interaction Models as a Mechanism for Sterile Neutrino Dark Matter Production

Abstract

We revisit sterile-neutrino production enabled by nonstandard interactions (NSI) among active neutrinos mediated by new bosons. We focus on vector mediators, including neutrinophilic, gauged , and realizations that modify in-medium dispersion and scattering, thereby altering the active-sterile conversion history. Building on a novel production framework with NSI thermal potentials and collision integrals, we compute nonthermal phase-space distributions across sterile neutrino mixing and NSI parameters and map each point to an equivalent thermal warm dark matter particle mass via linear-theory transfer function fitting with cosmological structure-formation Boltzmann solver. This enables a direct reinterpretation of state-of-the-art structure-formation limits from Milky Way satellites, strong lensing, and the Lyman- forest. These limits, in conjunction with X-ray decay searches, as well as results from a wide variety of particle physics experiments allow for a more complete examination of these models. We find that these vector-mediated models are ruled out when the full combination of current constraints, listed above, are taken into account. NSI scalar-mediated models and models with low-reheating temperatures remain viable.

Paper Structure

This paper contains 16 sections, 8 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Vector-Mediated Nonstandard Interaction Models
  3. Neutrinophilic Vector
  4. Gauged $U(1)_{L_\mu-L_\tau}$
  5. Gauged $U(1)_{B-L}$
  6. Methods
  7. Production with NSI
  8. Relating $g_V$ and $m_V$
  9. Mapping to structure formation
  10. Momentum spectra and transfer functions
  11. Astrophysical and particle constraints used
  12. Results
  13. Neutrinophilic
  14. Gauged $U(1)_{L_\mu-L_\tau}$
  15. Gauged $U(1)_{B-L}$
  16. ...and 1 more sections

Figures (3)

  • Figure 1: The $g_V$-$m_V$ relations are presented for two points using the Neutrinophilic production model. Each curve represents the valid region of parameter space where the production creates the full relic dark matter density. Point A highlights the high-mass case, point B highlights the intermediate mass case, while point C highlights the low mass case.
  • Figure 2: Shown here are the PSDs associated with the labeled points in Fig. \ref{['fig:s-curve']}.
  • Figure 3: Shown is the full sterile neutrino dark matter parameter space under Neutrinophilic vector-mediated NSI production, $L_\mu-L_\tau$ vector-mediated NSI production, and ${L_\mu-L_\tau}$ vector-mediated NSI production. The blue line is the standard DW production band. The dashed orange contour is the thermal WDM particle mass lower bound from the Zelko+ Zelko:2022tgf, disfavoring the region left of the line. The green dashed line is structure in addition to particle physics bounds as described in Ref. Kelly:2020pcy. The red cross-hatched X-ray exclusion region is the combination of Chandra, XMM-Newton, NuSTAR and SPI/INTEGRAL at 95% C.L. upper limits Perez:2016tcqRoach:2019ctwRoach:2022lgoKrivonos:2024yvmFischer:2022pse.