Dark matter relic density in strongly interacting dark sectors with light vector mesons

Stable dark matter particles may arise as pseudo-Goldstone bosons from the confinement of dark quarks interacting via a non-Abelian gauge force. Their relic abundance is determined not by annihilations into visible particles but by dark pion number-changing processes within the dark sector, such as <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mn>3</a:mn><a:msub><a:mi>π</a:mi><a:mi>D</a:mi></a:msub><a:mo stretchy="false">→</a:mo><a:mn>2</a:mn><a:msub><a:mi>π</a:mi><a:mi>D</a:mi></a:msub></a:math>. However, if the dark vector mesons <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:msub><d:mi>ρ</d:mi><d:mi>D</d:mi></d:msub></d:math> are light enough for <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mn>3</f:mn><f:msub><f:mi>π</f:mi><f:mi>D</f:mi></f:msub><f:mo stretchy="false">→</f:mo><f:msub><f:mi>π</f:mi><f:mi>D</f:mi></f:msub><f:msub><f:mi>ρ</f:mi><f:mi>D</f:mi></f:msub></f:math> annihilations to be kinematically allowed, this process dominates and significantly delays freeze-out. As a result, the preferred dark matter mass scale increases and bounds from the Bullet Cluster can be evaded. Published by the American Physical Society 2024