发表机构
Nanjing Normal University; Nanjing Key Laboratory of Particle Physics and Astrophysics（南京师范大学; 南京粒子物理与天体物理重点实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究通过维度-6 anapole 和 charge-radius 算符耦合的 iDM 的 freeze-in 产生，利用 X 射线观测约束衰变信号，并探讨其解释 LZ 信号的可能性。
AI 中文摘要
我们研究了通过维度-6 跃迁 anapole 和 charge-radius 算符与标准模型耦合的非弹性暗物质（iDM）的 freeze-in 产生及其实验探针。这些相互作用源于对破缺的 $U(1)_D$ 矢量门户中的重暗光子进行积分消除。我们关注质量劈裂低于双电子阈值的区域，此时激发态衰变在宇宙学上是长寿命的，并且主要通过 $\chi_1\to\chi_0+3\gamma$ 衰变，产生独特的 keV--MeV 光子谱。我们在 Euler--Heisenberg 极限下解析计算了衰变率和光子谱，并使用完整单圈振幅评估了有限电子质量修正。随后，我们将 X 射线限制与 freeze-in 遗迹密度目标以及互补的直接探测（DD）和加速器约束相结合。存活的 $\chi_1$ 群体还会在 DD 实验中产生放热下散射信号，包括解释 LZ 信号的可能性，而三光子衰变则受到 X 射线数据的约束。在 $\Delta=900\\,\mathrm{keV}$ 时，INTEGRAL/SPI 探测了 freeze-in 目标的玻尔兹曼抑制的高质量分支，而 NuSTAR 在 $\Delta=100\\,\mathrm{keV}$ 时的限制则明显较弱，这是因为衰变宽度对劈裂的强烈依赖性。我们的结果展示了 X 射线观测作为通过退耦矢量门户探测 freeze-in 以及控制 iDM 产生的再加热温度的潜力。
英文摘要
We study freeze-in production and experimental probes of inelastic dark matter (iDM) coupled to the Standard Model through dimension-6 transition anapole and charge-radius operators. These interactions arise upon integrating out the heavy dark photon of a broken $U(1)_D$ vector portal. We focus on mass splittings below the dielectron threshold, where the excited-state decay is cosmologically long-lived and decays predominantly through $χ_1\toχ_0+3γ$, producing a distinctive keV--MeV photon spectrum. We calculate the decay rate and photon spectrum analytically in the Euler--Heisenberg limit and evaluate finite-electron-mass corrections using the full one-loop amplitude. We then combine X-ray limits with freeze-in relic density targets and complementary direct detection (DD) and accelerator constraints. The surviving $χ_1$ population also leads to exothermic downscattering signatures at DD experiments, including the possibility of explaining the LZ signal, while the three-photon decay is constrained by X-ray data. At $Δ=900\,\mathrm{keV}$, INTEGRAL/SPI probes the Boltzmann-suppressed high-mass branches of the freeze-in targets, whereas the NuSTAR limits at $Δ=100\,\mathrm{keV}$ are substantially weaker because of the steep splitting dependence of the decay width. Our results demonstrate the potential of X-ray observations as a probe of freeze-in through a decoupled vector portal and of the reheating temperature governing the iDM production.
Comments19 pages, 6 figures
