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Search for Cosmic Ray Electron Boosted Dark Matter with the CDEX-10 Experiment

R. Xu, L. T. Yang, Q. Yue, K. J. Kang, Y. J. Li, H. P. An, Greeshma C., J. P. Chang, H. Chen, Y. H. Chen, J. P. Cheng, J. Y. Cui, W. H. Dai, Z. Deng, Y. X. Dong, C. H. Fang, H. Gong, Q. J. Guo, T. Guo, X. Y. Guo, L. He, J. R. He, H. X. Huang, T. C. Huang, S. Karmakar, Y. S. Lan, H. B. Li, H. Y. Li, J. M. Li, J. Li, M. C. Li, Q. Y. Li, R. M. J. Li, X. Q. Li, Y. L. Li, Y. F. Liang, B. Liao, F. K. Lin, S. T. Lin, J. X. Liu, R. Z. Liu, S. K. Liu, Y. D. Liu, Y. Liu, Y. Y. Liu, H. Ma, Y. C. Mao, A. Mureed, H. Pan, N. C. Qi, J. Ren, X. C. Ruan, M. B. Shen, H. Y. Shi, M. K. Singh, T. X. Sun, W. L. Sun, C. J. Tang, Y. Tian, H. F. Wan, G. F. Wang, J. Z. Wang, L. Wang, Q. Wang, Q. Wang, Y. F. Wang, Y. X. Wang, H. T. Wong, Y. C. Wu, H. Y. Xing, K. Z. Xiong, Y. Xu, T. Xue, Y. L. Yan, N. Yi, C. X. Yu, H. J. Yu, X. Yu, M. Zeng, Z. Zeng, F. S. Zhang, P. Zhang, P. Zhang, Z. Y. Zhang, M. G. Zhao, J. F. Zhou, Z. Y. Zhou, J. J. Zhu

TL;DR

The paper investigates sub-GeV dark matter detection via cosmic ray electron boosted DM (CReDM) and chi-e scattering in germanium detectors. It computes the CReDM flux from GALPROP-based CRE spectra and a spatial distribution, tied to a Navarro-Frenk-White density profile, and evaluates heavy and light mediator scenarios with energy-dependent cross sections. Using the CDEX-10 exposure of 205.4 kg d and a threshold of 160 eVee, it derives 90% CL exclusions on the cross section $\bar{\sigma}_{\chi e}$ as a function of dark matter mass $m_\chi$, finding that the heavy mediator case beats SHM limits for $m_\chi$ below 0.6 MeV and the light mediator case provides the best sensitivity in the 1 keV–0.5 MeV range. The study notes limitations from a non-relativistic detector response and low-energy CRE extrapolation, and outlines future work to incorporate relativistic effects for improved accuracy.

Abstract

We present new constraints on the cosmic ray electron boosted light dark matter (CReDM) using the 205.4 kg$\cdot$day data of the CDEX-10 experiment located at the China Jinping Underground Laboratory. The cosmic ray electron spectrum and distribution in the Galaxy are generated by the $\tt GALPROP$ code package. In the calculation process of DM-electron scattering process in the Galaxy, we consider the energy-dependency of the DM-electron scattering cross section. The constraints on CReDM are set for both heavy and light mediator scenarios using the CDEX-10 dataset. The result exceeds previous Standard Halo Model (SHM) limits for DM mass lower than 0.6 MeV in heavy mediator case and corresponds to the best sensitivity among all direct detection experiments from 1 keV to 0.5 MeV in the light mediator scenario.

Search for Cosmic Ray Electron Boosted Dark Matter with the CDEX-10 Experiment

TL;DR

The paper investigates sub-GeV dark matter detection via cosmic ray electron boosted DM (CReDM) and chi-e scattering in germanium detectors. It computes the CReDM flux from GALPROP-based CRE spectra and a spatial distribution, tied to a Navarro-Frenk-White density profile, and evaluates heavy and light mediator scenarios with energy-dependent cross sections. Using the CDEX-10 exposure of 205.4 kg d and a threshold of 160 eVee, it derives 90% CL exclusions on the cross section as a function of dark matter mass , finding that the heavy mediator case beats SHM limits for below 0.6 MeV and the light mediator case provides the best sensitivity in the 1 keV–0.5 MeV range. The study notes limitations from a non-relativistic detector response and low-energy CRE extrapolation, and outlines future work to incorporate relativistic effects for improved accuracy.

Abstract

We present new constraints on the cosmic ray electron boosted light dark matter (CReDM) using the 205.4 kgday data of the CDEX-10 experiment located at the China Jinping Underground Laboratory. The cosmic ray electron spectrum and distribution in the Galaxy are generated by the code package. In the calculation process of DM-electron scattering process in the Galaxy, we consider the energy-dependency of the DM-electron scattering cross section. The constraints on CReDM are set for both heavy and light mediator scenarios using the CDEX-10 dataset. The result exceeds previous Standard Halo Model (SHM) limits for DM mass lower than 0.6 MeV in heavy mediator case and corresponds to the best sensitivity among all direct detection experiments from 1 keV to 0.5 MeV in the light mediator scenario.
Paper Structure (7 sections, 13 equations, 5 figures, 1 table)

This paper contains 7 sections, 13 equations, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. CReDM flux in the space
  3. Cosmic ray electron flux in the Galaxy
  4. CReDM flux calculation
  5. Expected Spectra in Ge Detectors
  6. Exclusion results
  7. Conclusions and discussions.

Figures (5)

  • Figure 1: The LIS of cosmic ray electrons generated by $\tt GALPROP$ is shown by the black line. The dashed line corresponds to the extrapolation at low energy. The measured data of the AMS-02 ams02 and Voyager I voyager are shown in red and blue points, respectively.
  • Figure 2: (a) The CRE fluxes as a function of distance $R$ from the Galactic Center at different heights $z$ from the Galactic disk. The kinetic energies of the CRE are set to be 10 GeV. (b) The CRE fluxes as a function of height $z$ from the Galactic disk at different radii from the GC. The kinetic energies of the CRE are set to be 10 GeV.
  • Figure 3: The CReDM fluxes scaled by $T_{\chi}$ for different DM masses with $\bar{\sigma}_{\chi e} = 10^{-30}\ \rm cm^2$. The solid and dashed lines in upper and lower panel correspond to the heavy and light mediator cases, respectively. When the boosted DM velocity is more than $10^5\ \rm km/s$, the solid line is changed to dashed line. The dotted lines are calculated by using the energy independent cross section in Eq. \ref{['independent']}. The DM flux under the SHM scenario with mass 1 MeV is plotted for comparison. The SHM flux in (a) is scaled by $10^{-6}$.
  • Figure 4: The total expected rate of DM mass 10 keV and $\chi$-$e$ scattering cross section $10^{-31} \rm cm^2$. The red and blue lines correspond to the light and heavy mediator cases, respectively. The spectra are corrected with energy resolution. The standard deviation of the energy resolution is 35.8 + 16.6$\times E^{\frac{1}{2}}$ (eV), where $E$ is expressed in keV. The CDEX-10 experiment data after subtracting the contributions from cosmogenic radionuclides X-ray peaks are also shown for comparison. The CDEX-10 analysis threshold of 160 eVee is shown with a dotted line.
  • Figure 5: The exclusion region derived from the CDEX-10 dataset is demonstrated in red line, with the CRE acceleration mechanism adopted. The upper and lower panel corresponds to the heavy and light mediator cases, respectively. The shaded area corresponds to the SHM constraints from current direct detection experiments SENSEIDAMIC. Exclusion regions from the phenomenological CReDM analyses using XENONnT and Super-K data energy_dependent for both the heavy and light scalar mediator case are also shown for comparison.