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Direct Detection of Leptophobic Dark Matter with Electronic Collective Excitations

Yifan Hu, Ning Liu, Liangliang Su, Bin Zhu

TL;DR

Problem: leptophobic dark matter that couples only to quarks may still yield electron signals via hadronic-loop interactions. Approach: compute the LDM–electron scattering amplitude mediated by a light vector boson with proton-loop induced photon mixing, and express rates through the energy-loss function $\mathrm{Im}(-1/\epsilon(Q,\omega))$; evaluate two relativistic DM fluxes (BDM and CRDM) to predict plasmon excitations in a silicon detector with the kinematic threshold $v_\chi \gtrsim 0.01c$. Findings: with SENSEI data, derive 90% CL exclusions on the spin-independent LDM–nucleon cross section $\bar{\sigma}_{\chi n}$ for keV–MeV DM, with plasmon regions at $\omega \sim 10$–$25$ eV contributing most strongly, and CRDM bounds comparable to certain BDM benchmarks. Significance: establishes electronic collective excitations as a practical probe of sub-GeV leptophobic DM and motivates future, lower-threshold detectors.

Abstract

Some new-generation dark matter detection experiments are primarily designed to search for the dark matter-electron interactions, but they can also be utilized to probe models in which dark matter couples exclusively to nucleon via the quantum effects. The hadronic loop-induced interactions can directly excite plasmons in semiconductors, thereby providing an additional channel for detecting the leptophobic dark matter. In this work, we investigate plasmon excitations in silicon detectors induced by boosted dark matter and cosmic-ray up-scattering dark matter via the hadronic loop process. By analyzing the available experimental data, we derive new exclusion limits on the leptophobic dark matter-nucleon scattering cross section.

Direct Detection of Leptophobic Dark Matter with Electronic Collective Excitations

TL;DR

Problem: leptophobic dark matter that couples only to quarks may still yield electron signals via hadronic-loop interactions. Approach: compute the LDM–electron scattering amplitude mediated by a light vector boson with proton-loop induced photon mixing, and express rates through the energy-loss function ; evaluate two relativistic DM fluxes (BDM and CRDM) to predict plasmon excitations in a silicon detector with the kinematic threshold . Findings: with SENSEI data, derive 90% CL exclusions on the spin-independent LDM–nucleon cross section for keV–MeV DM, with plasmon regions at – eV contributing most strongly, and CRDM bounds comparable to certain BDM benchmarks. Significance: establishes electronic collective excitations as a practical probe of sub-GeV leptophobic DM and motivates future, lower-threshold detectors.

Abstract

Some new-generation dark matter detection experiments are primarily designed to search for the dark matter-electron interactions, but they can also be utilized to probe models in which dark matter couples exclusively to nucleon via the quantum effects. The hadronic loop-induced interactions can directly excite plasmons in semiconductors, thereby providing an additional channel for detecting the leptophobic dark matter. In this work, we investigate plasmon excitations in silicon detectors induced by boosted dark matter and cosmic-ray up-scattering dark matter via the hadronic loop process. By analyzing the available experimental data, we derive new exclusion limits on the leptophobic dark matter-nucleon scattering cross section.
Paper Structure (3 sections, 17 equations, 4 figures, 1 table)

This paper contains 3 sections, 17 equations, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Leptophobic Dark Matter-electron scattering in semiconductor
  3. Result

Figures (4)

  • Figure 1: Schematic diagram of LDM-electron scattering process through a hadronic loop in a semiconductor detector.
  • Figure 2: Top panel: The differential event rate $\mathrm{d}R/\mathrm{d}\omega$ as a function of the deposited energy $\omega$; Bottom panel: Event rate $R_{\mathcal{Z}}$ as a function of the ionized charge $\mathcal{Z}$. The solid lines denotes the BDM with $m_{\chi_{1}}=1$ MeV, $m_{\chi_{1}} = 1$ keV and thermally averaged the annihilation cross section $\langle \sigma v \rangle = 5\times 10^{-26} \mathrm{cm^3/s}$. The dashed lines are the results of 1 keV CRDM. The brenchmark DM-nucleon scattering cross section is $\bar{\sigma}_{\chi n} = 10^{-32} \; \mathrm{cm}^2$.
  • Figure 3: The 90% confidence level exclusion limits on the LDM-nucleon scattering cross section $\bar{\sigma}_{\chi n}$ as a function of the mass splitting $\Delta m_{\chi} = m_{\chi_1} - m_{\chi_2}$ in the two-component BDM model. Top panel: results with the heavier component mass fixed at $m_{\chi_1} = 1~\mathrm{MeV}$. Bottom panel: results with the lighter component mass fixed at $m_{\chi_2} = 1~\mathrm{keV}$.
  • Figure 4: The 90% C.L. upper limits on the LDM-nucleon scattering cross section $\bar{\sigma}_{\chi n}$ as a function of DM mass. The red line corresponds to CRDM, while the dashed and solid blue lines represent the two-component BDM scenario with $m_{\chi_1} = 1~\mathrm{MeV}$ and $m_{\chi_1} = 0.1~\mathrm{MeV}$, respectively. For comparison, existing cosmological and astrophysical constraints are also shown: CMB from Planck 2015 Planck:2015bpvGluscevic:2017ywp (purple), Milky Way satellite galaxies Nadler:2019zrb (green), and the Lyman-$\alpha$ forest Rogers:2021byl (yellow).