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New Constraints on Cosmic-ray boosted Sub-GeV Dark Matter via Light Mediators

Yang Yu, Guan-Sen Wang, Bo Zhang, Tian-Peng Tang, Bing-Yu Su, Lei Feng

TL;DR

This work tackles the challenge of detecting sub-GeV dark matter by leveraging cosmic-ray boosted dark matter (CRDM) to upscatter halo DM to detectable velocities. It connects the CRDM mechanism to explicit particle-physics models, analyzing four mediator scenarios—scalar, vector, pseudoscalar, and axial-vector—and deriving constraints on both the DM-nucleon cross-section and the underlying couplings using LZ, XENON, and Borexino data over mediator masses from $m_ ext{med}\in[10^{-6},1]\ \mathrm{GeV}$. A key result is the turnover in exclusion limits around $m_ ext{med}\sim 10^{-2}$–$10^{-3}$ GeV, where momentum-transfer dependence transitions from momentum-dominated to mass-dominated scattering, underscoring the importance of including propagator effects in light-mediator scenarios. The findings extend terrestrial sensitivity into the sub-GeV regime and provide a framework for comparing CRDM constraints with other DM searches across different mediator theories.

Abstract

Traditional direct detection experiments lack the sensitivity to probe the sub-GeV dark matter (DM), primarily due to the low energy of the expected nuclear recoils. In this work, we investigate cosmic-ray (CR) upscattering as a mechanism to accelerate DM particles to detectable velocities in underground experiments. By analyzing four models of DM-nucleon interactions -- namely scalar, vector, pseudoscalar, and axial-vector mediators -- we derive constraints on the coupling parameters using data from the LZ, XENON, and Borexino experiments, covering mediator mass from $10^{-6}$ to $1$ GeV. As the mediator mass varies, the shift in dominance between momentum transfer and mediator mass leads to a turnover in the constraints around $10^{-2}$--$10^{-3}~\mathrm{GeV}$. Our results extend the reach of direct detection into the sub-GeV window and clarify the critical role of momentum dependence in light-mediator scenarios.

New Constraints on Cosmic-ray boosted Sub-GeV Dark Matter via Light Mediators

TL;DR

This work tackles the challenge of detecting sub-GeV dark matter by leveraging cosmic-ray boosted dark matter (CRDM) to upscatter halo DM to detectable velocities. It connects the CRDM mechanism to explicit particle-physics models, analyzing four mediator scenarios—scalar, vector, pseudoscalar, and axial-vector—and deriving constraints on both the DM-nucleon cross-section and the underlying couplings using LZ, XENON, and Borexino data over mediator masses from . A key result is the turnover in exclusion limits around – GeV, where momentum-transfer dependence transitions from momentum-dominated to mass-dominated scattering, underscoring the importance of including propagator effects in light-mediator scenarios. The findings extend terrestrial sensitivity into the sub-GeV regime and provide a framework for comparing CRDM constraints with other DM searches across different mediator theories.

Abstract

Traditional direct detection experiments lack the sensitivity to probe the sub-GeV dark matter (DM), primarily due to the low energy of the expected nuclear recoils. In this work, we investigate cosmic-ray (CR) upscattering as a mechanism to accelerate DM particles to detectable velocities in underground experiments. By analyzing four models of DM-nucleon interactions -- namely scalar, vector, pseudoscalar, and axial-vector mediators -- we derive constraints on the coupling parameters using data from the LZ, XENON, and Borexino experiments, covering mediator mass from to GeV. As the mediator mass varies, the shift in dominance between momentum transfer and mediator mass leads to a turnover in the constraints around --. Our results extend the reach of direct detection into the sub-GeV window and clarify the critical role of momentum dependence in light-mediator scenarios.
Paper Structure (8 sections, 7 equations, 3 figures)

This paper contains 8 sections, 7 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Boosted Dark Matter
  3. Particle Model
  4. Cosmic-ray Boosted Dark Matter
  5. Model Constraints
  6. Constraints on Constant Cross-sections
  7. Constraints on Light Mediator Models
  8. Conclusion

Figures (3)

  • Figure 1: Bounds on SI constant DM-nucleon scattering cross-section. The LZLZ:2024zvo (red), Xenon1tXENON:2018voc (blue), and MiniBooNEKaragiorgi:2006jf (green) constraints are shown with the corresponding line styles, and the solid and dashed lines represent the local value out to a distance of 1 kpc and 10 kpc. We compare our result with CMB observationsXu:2018efh (orange), gas cloud coolingBhoonah:2018wmw (purple) and direct detection limit (gray) which incorporates results from SuperCDMSSuperCDMS:2018mne, DarkSide-50DarkSide:2022dhxDarkSide-50:2022qzh, DAMICDAMIC:2016lrs, NEWS-GNEWS-G:2017pxg, CRESSTCRESST:2019jnq, CDEXCDEX:2019hzn, XENONXENON:2019zpr, and EDELWEISSEDELWEISS:2019vjvEDELWEISS:2022ktt.
  • Figure 2: Constraints on the DM-nucleon scattering cross section for scalar and vector mediator models. Left (right) panels show the results for a mediator mass of 1 MeV (1 GeV). Blue, green, and red curves correspond to the LZ, XENON1T, and Borexino limits, and the shaded regions indicate the excluded parameter space.
  • Figure 3: Constraints on DM-nucleon couplings for the four benchmark DM masses. The upper panels show SI results for scalar and vector mediators obtained from the LZ experiment, while the lower panels show SD results for pseudoscalar and axial-vector mediators from the Borexino experiment. Blue, green, red, and purple lines correspond to DM masses of 1 MeV, 10 MeV, 100 MeV, and 1000 MeV, respectively. Solid lines indicate the full calculation including both the mediator mass and momentum terms in the propagator, while dashed lines retain only the mass term.