Nailing down the theoretical uncertainties of $\overline{\rm D}$ spectrum produced from dark matter

TL;DR

This paper introduces a new coalescence model based on the Wigner formalism with Argonne v18 wavefunction, significantly reducing uncertainties in predicting antideuteron fluxes from dark matter for cosmic ray experiments.

Contribution

The authors develop a parameter-free Wigner formalism model for antideuteron production, improving accuracy and reducing theoretical uncertainties in dark matter indirect detection predictions.

Findings

Model reproduces ALEPH antideuteron multiplicity data

Reduces uncertainty in antideuteron source spectra to a few percent

Provides tabulated spectra for DM masses 5 GeV to 100 TeV

Abstract

The detection of cosmic antideuterons ($\overline{\rm D}$) at kinetic energies below a few GeV/n could provide a smoking gun signature for dark matter (DM). However, the theoretical uncertainties of coalescence models have represented so far one of the main limiting factors for precise predictions of the $\overline{\rm D}$ flux. In this Letter we present a novel calculation of the $\overline{\rm D}$ source spectra, based on the Wigner formalism, for which we implement the Argonne $v_{18}$ antideuteron wavefunction that does not have any free parameters related to the coalescence process. We show that the Argonne Wigner model excellently reproduces the $\overline{\rm D}$ multiplicity measured by ALEPH at the $Z$-boson pole, which is usually adopted to tune the coalescence models based on different approaches. Our analysis is based on Pythia~8 Monte Carlo event generator and the state-of-the-art Vincia shower algorithm. We succeed, with our model, to reduce the current theoretical uncertainty on the prediction of the $\overline{\rm D}$ source spectra to a few percent, for $\overline{\rm D}$ kinetic energies relevant to DM searches with GAPS and AMS, and for DM masses above a few tens of GeV. This result implies that the theoretical uncertainties due to the coalescence process are no longer the main limiting factor in the predictions. We provide the tabulated source spectra for all the relevant DM annihilation/decay channels and DM masses between 5 GeV and 100 TeV, on the CosmiXs github repository (https://github.com/ajueid/CosmiXs.git).