Parametric coincidence in the baryon to dark matter ratio from Affleck-Dine baryogenesis and UV freeze-in dark matter

We highlight that the observed concurrence between the baryon and dark matter relic densities can be explained via a parametric coincidence between two distinct production mechanisms: Affleck-Dine baryogenesis and dark matter UV freeze-in. In the Affleck-Dine mechanism, the baryon asymmetry is naturally proportional to the inflationary reheating temperature <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>T</a:mi><a:mrow><a:mi>rh</a:mi></a:mrow></a:msub></a:math>, which also plays a critical role in setting the relic abundance of UV freeze-in dark matter. Since Affleck-Dine baryogenesis requires flat directions in the potential, the framework is inherently supersymmetric, offering compelling UV freeze-in dark matter candidates such as the gravitino. We outline scenarios in which <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msub><c:mi>T</c:mi><c:mrow><c:mi>rh</c:mi></c:mrow></c:msub></c:math> simultaneously determines both relic abundances, resulting in a baryon-to-dark matter ratio of order unity that is largely insensitive to <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>T</e:mi><e:mrow><e:mi>rh</e:mi></e:mrow></e:msub></e:math>. We also discuss the conditions required to avoid Q-ball formation or dark matter production by other mechanisms, such as next-to-lightest supersymmetric particle decays, to preserve the parametric coincidence between baryon and dark matter abundances.