arXiv subjects

Haoming Nie

Publications and source records attributed to Haoming Nie.

5 recordsLinked to original sources

arXiv2026

Solar Reflection of Inelastic Dark Matter

Solar-reflected dark matter (SRDM) consists of dark-matter particles up-scattered and accelerated by energetic electrons in the solar interior, producing a high-velocity tail that can enhance signals in direct-detection experiments, especially for MeV-scale masses. We consider an inelastic dark matter (iDM) model, in which solar scattering populates the excited state; subsequent de-excitation in terrestrial detectors releases the mass-splitting energy, substantially helping the energy release of the collision to be larger than the detector threshold. Using detailed Monte Carlo simulations, we generate the velocity and energy distributions of solar-reflected iDM over a range of dark-matter masses $m_\chi$ and mass splittings $\Delta$. We then compute event rates and energy depositions for current xenon and semiconductor experiments. Our results show that these experiments can place new constraints on the parameter space of MeV-scale iDM.

hep-ph↗

arXiv2025

Dark Matter implications from the LZ, PandaX-4T and XENONnT Data

We investigate a possible dark matter origin of the high-energy nuclear-recoil-like events in data from liquid xenon time projection chamber experiments, including LZ, PandaX-4T, and XENONnT, which cannot be explained by standard elastic spin-independent WIMP scattering. Using our unified DIAMX framework, built on openly available data and likelihood models, we perform the first combined profile-likelihood fits to multiple WIMP-search datasets with a total exposure of approximately 8.8 tonne $\times$ year. We consider two broad classes of dark matter-nucleon interactions, involving either velocity-dependent cross sections or inelastic (endo- and exothermic) scattering, which can reproduce the observed high-energy recoil spectrum, reaching local significances up to $3.5\sigma$. We further quantify the impact of $^{124}$Xe double electron capture (DEC) backgrounds, finding that variations in the poorly known DEC charge yields can shift the inferred significances from a null-like result to $3.5\sigma$. We further note that extending the same analysis to data from all three experiments with recoil energies up to $300~\mathrm{keV}$, when available, will provide a powerful test of the dark matter interpretation, since the $^{124}$Xe DEC background is expected to be negligible in this high-energy range.

hep-ph↗

arXiv2025

Solar Reflected Dark Matter under the Influence of a Dark Magnetic Field

The scattering of dark matter particles within the Sun's hot plasma can lead to the acceleration of dark matter, producing a high-energy solar-reflected DM flux detectable in ground-based experiments. In the vector portal model, the dark matter has a sub-MeV-scale mass, and interactions between the dark matter and Standard Model particles are mediated by a hidden vector field--referred to as a dark photon--which kinetically mixes with the conventional photon through a small mixing angle. Furthermore, the solar plasma generates intense magnetic fields. Due to the photon-dark photon mixing, this simultaneously sources a ``dark magnetic field". For sufficiently low dark photon masses, this dark magnetic field is capable of deflecting dark matter particles traversing the Sun. We found that if the dark magnetic force is sufficiently strong, the dark magnetic field becomes a wall, preventing the dark matter particles from reaching the deep core region, suppressing their reflected flux. This scenario corrects the sensitivity of the solar-reflected dark matter detection, offering critical insights for ground-based experiments aiming to probe dark matter.

hep-ph↗

arXiv2025

Modulation signals of solar reflected dark matter in crystal-based detectors

The scattering of light dark matter (DM) off thermal electrons within the Sun generates a ``fast'' sub-component of the DM flux that can be detected in underground direct detection experiments. This ``fast'' sub-component has a specific origin-namely, from the Sun. In this study, we demonstrate that in detectors composed of single crystals, like in Bragg scattering, the collision rate and energy deposition are influenced by the angle between the momentum of the incoming DM and the orientations of the crystallographic axes. This results in a directional modulation of the signal. We calculate the magnitude of directional modulations for both germanium and silicon crystals, considering both the contact interaction and light mediator scenarios. Our findings indicate that for the contact interaction case, the daily modulation of the collision rate is approximately 0.1% of the total, while in the light mediator case, it can reach as high as 30%. Additionally, our analysis suggests that future ton-scale crystal detectors will be able to explore the freeze-in DM regime with $m_{\rm{DM}} \sim 0.1 \rm{MeV}$.

hep-ph↗

arXiv2023

Solar Reflection of Dark Matter

The scattering of light dark matter off thermal electrons inside the Sun produces a "fast" sub-component of the dark matter flux that may be detectable in underground experiments. We update and extend previous work by analyzing the signatures of dark matter candidates which scatter via light mediators. Using numerical simulations of the dark matter-electron interaction in the solar interior, we determine the energy spectrum of the reflected flux, and calculate the expected rates for direct detection experiments. We find that large Xenon-based experiments (such as XENON1T) provide the strongest direct limits for dark matter masses below a few MeV, reaching a sensitivity to the effective dark matter charge of better than $\sim 10^{-9}e$.

hep-ph↗