Cosmic Ray-Boosted Dark Matter at IceCube (2405.00086v1)

Abstract: Cosmic ray (CR) upscattering of dark matter is considered as one of the most straightforward mechanisms to accelerate ambient dark matter, making it detectable at high threshold, large volume experiments. In this work, we revisit CR upscattered dark matter signals at the IceCube detector, focusing on lower energy data than was considered before. We consider both scattering with electrons and nuclei. In the latter, we include both elastic and deep-inelastic scattering computations. As concrete examples, we consider two benchmark models; Fermion dark matter with vector and scalar mediators. We compare our model projections with the most current constraints and show that the IceCube detector can detect CR-boosted dark matter especially with masses below $\sim$ 100 keV when scattering with electrons and $\sim$ MeV in the nucleon scattering case.

• The paper demonstrates that IceCube can probe dark matter below ~100 keV for electron scattering and a few MeV for nucleon scattering.
• It employs detailed modeling of cosmic ray upscattering with both vector and scalar mediator frameworks, incorporating elastic and deep inelastic scattering processes.
• The study sets competitive interaction limits and highlights the potential for improved detection with upcoming low-energy sensitivity upgrades at IceCube.

Overview of Cosmic Ray-Boosted Dark Matter Detection at IceCube

This paper presents an investigation into the detection of cosmic ray (CR)-boosted dark matter (DM) at the IceCube neutrino detector. It critically examines the potential for detecting CR-upscattered DM particles through their interactions with both electrons and nucleons at IceCube, focusing on short-range interactions mediated by vector and scalar bosons. The paper spans both theoretical modeling and data analysis, paving the way for future exploration of DM parameter space at relatively low masses, leveraging the expansive volume and capabilities of the IceCube detector.

Theoretical Framework and Models

The authors consider CR upscattering, a mechanism by which ambient DM is accelerated by interactions with high-energy cosmic rays, subsequently rendering it detectable by high-threshold detectors such as IceCube. Two benchmark models are proposed: fermionic DM with vector mediators and scalar mediators. Such models facilitate the precise calculation of the differential cross-sections for DM scattering with electrons and nucleons (protons). The framework is rigorous, including both elastic and deep inelastic scattering (DIS) processes, which are essential at the energy scales considered.

Methodology

A notable aspect of this work is the utilization of IceCube's existing low-energy data, extending their analysis below the previously analyzed energy thresholds, thereby improving sensitivity to low-mass DM candidates. For DM-electron interactions, the team includes a detailed examination of CR upscattering by electron cosmic rays, recognizing the relativistic effects on cross-section calculations. On the nuclear side, upscattering primarily via protons is explored, incorporating the complex phenomenology of DIS, essential due to the high transfer energies involved when CR protons collide with DM particles.

Results and Constraints

The results challenge existing bounds on DM-electron and DM-proton interaction cross-sections. Specifically, the authors demonstrate that IceCube is capable of setting competitive limits on DM masses below approximately 100 keV for electron scattering and below a few MeV for nucleon scattering. The constraints derived for a vector mediator in the DM-proton interactions align closely with or surpass other existing limits, illustrating IceCube's potential as a unique probe of lighter DM particles in the sub-GeV mass range.

The authors contend that the attenuation of upscattered DM through the Earth's crust requires careful consideration, with their analysis accounting for propagation losses through 1.45 kilometers of ice before reaching the detector. This analysis includes constraints on scattering events that might trigger the surrounding veto layer, meticulously ensuring that detected events are not erroneously rejected as backgrounds.

Implications and Future Work

The implications of this work bridge the practical and theoretical realms. Practically, it suggests that IceCube, albeit primarily a neutrino detector, holds untapped potential for DM searches, particularly for light DM that is otherwise elusive. Theoretically, it stimulates further exploration into varied DM models that interact through novel mediators, suggesting the viability of new search strategies that leverage atmospheric and astrophysical conditions favorable to DM detection.

While delineating current constraints, the authors propose that upcoming upgrades to IceCube, especially those enhancing its low-energy sensitivity, could markedly refine detection limits and expand the spectrum of detectable phenomena, thereby contributing significantly to the landscape of indirect DM detection methods. This foresight positions IceCube to potentially harmonize with other detectors in a multifaceted approach to DM exploration.

In conclusion, the work informs the astrophysical community about strategic leverage points within the existing detector infrastructures and underscores the necessity of a cross-disciplanary approach to unmask the properties of dark matter. The analysis represents a significant step in elucidating the capabilities of cosmic ray interactions within detector environments, suggesting avenues for extended analysis with upgraded facilities.