# Effect of polarisation and choice of event generator on spectra from dark matter annihilations

## TL;DR

This paper examines how the choice of event generator and particle polarisation affect the predicted energy spectra of secondary particles from dark matter annihilations, highlighting the importance of these factors in indirect detection analyses.

## Contribution

It provides a comparative analysis of Pythia8 and Herwig7 for secondary particle yields and investigates the impact of polarisation on neutrino flux predictions from dark matter annihilations.

## Key findings

- Differences between event generators are larger for hadronic yields than leptonic.
- Polarisation significantly affects leptonic spectra, especially neutrinos from the Sun.
- Propagation effects in the Sun reduce the impact of polarisation differences.

## Abstract

If indirect detection searches are to be used to discriminate between dark matter particle models, it is crucial to understand the expected energy spectra of secondary particles such as neutrinos, charged antiparticles and gamma-rays emerging from dark matter annihilations in the local Universe. In this work we study the effect that both the choice of event generator and the polarisation of the final state particles can have on these predictions. For a variety of annihilation channels and dark matter masses, we compare yields obtained with Pythia8 and Herwig7 of all of the aforementioned secondary particle species. We investigate how polarised final states can change these results and do an extensive study of how the polarisation can impact the expected flux of neutrinos from dark matter annihilations in the centre of the Sun. We find that differences between the event generators are larger for yields of hadronic end products such as antiprotons, than for leptonic end products. Concerning polarisation, we conversely find the largest differences in the leptonic spectra. The large differences in the leptonic spectra point to the importance of including polarisation effects in searches for neutrinos from dark matter annihilations in the Sun. However, we find that these differences are ultimately somewhat washed out by propagation effects of the neutrinos in the Sun.