Inelastic Dark Photon Dark Matter for the LUX-ZEPLIN High-Recoil Event and the Galactic Halo Gamma-Ray Excess
- 1Department of Physics , Ibaraki University , Mito 310-8512 , Japan
Abstract
We show that a dark-photon dark matter framework can simultaneously account for two recently reported anomalies: the halo-like Galactic gamma-ray excess identified by Totani in 15 years of Fermi-LAT data, and the Enr=248±23 (stat)±23 (sys) keV nuclear-recoil event of interest reported by the LUX-ZEPLIN Collaboration. The dark matter is a U(1)X dark photon X with mass mX=420 GeV, stabilized by a dark parity that forbids kinetic mixing with the Standard Model photon. A light scalar mediator ϕ, required to explain the Totani excess via Sommerfeld enhancement, is joined by a second light scalar ϕ' that couples a nearly degenerate heavier vector partner V to X. The resulting inelastic transition X+N→ V+N, with mass splitting δ≃316 keV close to the kinematic endpoint for mX=420 GeV, naturally reproduces the localized LZ event once the detector energy resolution is included, while leaving the relic abundance and the halo phenomenology of the original Totani-motivated benchmark essentially unchanged.
Related
- Kaluza--Klein Dark-Photon Mediation of Inelastic Dark Matter at LUX-ZEPLIN
- Higgsino Dark Matter Interpretation of the LUX-ZEPLIN 248 keV Nuclear-Recoil Event
- Solar Neutrino Constraints on Inelastic Dark Matter Scattering in Light of Recent LUX-ZEPLIN Observations
- Sub-TeV Singlino Dark Matter in light from Sagittarius A∗ and LUX-ZEPLIN Nuclear-Recoil Event
- Inelastic dark matter and baryon flavor symmetry in light of LUX-ZEPLIN (LZ) experiment
BibTeX
@misc{yamashita2026inelastic,
title = {{Inelastic Dark Photon Dark Matter for the LUX-ZEPLIN High-Recoil Event and the Galactic Halo Gamma-Ray Excess}},
author = {Kimiko Yamashita},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.02868},
eprint = {2609.02868},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.02868},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Inelastic Dark Photon Dark Matter for the LUX-ZEPLIN High-Recoil Event and the Galactic Halo Gamma-Ray Excess
AU - Kimiko Yamashita
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2609.02868
UR - https://arxiv.org/abs/2609.02868
AB - We show that a dark-photon dark matter framework can simultaneously account for two recently reported anomalies: the halo-like Galactic gamma-ray excess identified by Totani in 15 years of Fermi-LAT data, and the E_nr=248±23 (stat)±23 (sys) keV nuclear-recoil event of interest reported by the LUX-ZEPLIN Collaboration. The dark matter is a U(1)_X dark photon X with mass m_X=420 GeV, stabilized by a dark parity that forbids kinetic mixing with the Standard Model photon. A light scalar mediator ϕ, required to explain the Totani excess via Sommerfeld enhancement, is joined by a second light scalar ϕ' that couples a nearly degenerate heavier vector partner V to X. The resulting inelastic transition X+N→ V+N, with mass splitting δ≃316 keV close to the kinematic endpoint for m_X=420 GeV, naturally reproduces the localized LZ event once the detector energy resolution is included, while leaving the relic abundance and the halo phenomenology of the original Totani-motivated benchmark essentially unchanged.
SN - 2331-8422
ER -