Freeze-in dark matter from a minimal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi><mml:mo>−</mml:mo><mml:mi>L</mml:mi></mml:math> model and possible grand unification
Physical review. D/Physical review. D.