Dark matter in a mirror solution to the strong CP problem

We study thermal production of dark matter (DM) in a realization of the minimal models of Bonnefoy [], where parity is used to solve the strong <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>C</a:mi><a:mi>P</a:mi></a:math> problem by transforming the entire Standard Model (SM) into a mirror copy. Although the mirror electron <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>e</c:mi><c:mo>′</c:mo></c:msup></c:math> is a good DM candidate, its viability is mired by the presence of the mirror up quark <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msup><e:mi>u</e:mi><e:mo>′</e:mo></e:msup></e:math>, whose abundance is intimately related to the <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msup><g:mi>e</g:mi><g:mo>′</g:mo></g:msup></g:math> abundance and must be suppressed. This can be achieved through a sequential freeze-in mechanism, where mirror photons are first produced from SM gluons, and then the mirror photons produce <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msup><i:mi>e</i:mi><i:mo>′</i:mo></i:msup></i:math>. After computing the details of this double freeze-in, we discuss the allowed parameter space of the model, which lies at the threshold of experimental observations. We find that this origin of <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msup><k:mi>e</k:mi><k:mo>′</k:mo></k:msup></k:math> DM requires a low reheating temperature after inflation and is consistent with the baryon asymmetry arising from leptogenesis, providing mirror neutrinos have a significant degeneracy. Finally, we show that this <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msup><m:mi>e</m:mi><m:mo>′</m:mo></m:msup></m:math> DM is not compatible with Higgs parity, the simplest scheme with exact parity, unless SM parameters deviate significantly from their central values or the minimal model is extended. Published by the American Physical Society 2024