Reliability of Monte Carlo event generators for gamma ray dark matter searches

TL;DR

This paper compares four Monte Carlo event generators to assess their differences in simulating gamma ray spectra for dark matter searches, highlighting significant discrepancies that could impact signal interpretation.

Contribution

It provides a systematic comparison of different Monte Carlo generators, revealing notable differences in gamma ray spectra simulations relevant for dark matter detection.

Findings

Significant differences observed between generators in gamma ray spectra.

Discrepancies may affect dark matter signal interpretation.

Differences are consistent across multiple channels.

Abstract

We study the differences in the gamma ray spectra simulated by four Monte Carlo event generator packages developed in particle physics. Two different versions of PYTHIA and two of HERWIG are analyzed, namely PYTHIA 6.418 and HERWIG 6.5.10 in Fortran and PYTHIA 8.165 and HERWIG 2.6.1 in C++. For all the studied channels, the intrinsic differences between them are shown to be significative and may play an important role in misunderstanding dark matter signals.