If the interaction rates between the visible and the dark sectors were never strong enough, the observed dark matter relic abundance could have been produced in the early Universe by non-thermal processes. This is what occurs in the so-called freeze-in mechanism. In the simplest version of the freeze-in paradigm, after dark matter is produced from the standard model thermal bath, its abundance is frozen and remains constant. However, thermalization and number-changing processes in the dark sector can have strong impacts, in particular enhancing the dark matter relic abundance by several orders of magnitude. Here we show that this enhancement can be computed from general arguments as the conservation of energy and entropy, independently from the underlying particle physics details of the dark sector. We also note that this result is quite general, and applies to FIMP production independently of being UV- or IR-dominated.
Freeze-in at Low Reheating and Direct Detection of Fermion Dark Matter
Ferdowsi University of Mashhad（马什哈德 Ferdowsi 大学）；Millennium Institute for Subatomic Physics at the High-Energy Frontier (SAPHIR)（高能前沿亚原子物理千年研究所 (SAPHIR)）
WIMP-like Dark Matter Without Thermalization At Freeze-Out
University of Wisconsin, Madison（威斯康星大学麦迪逊分校）；Wisconsin IceCube Particle Astrophysics Center (WIPAC), University of Wisconsin, Madison（威斯康星冰立方粒子天体物理中心，威斯康星大学麦迪逊分校）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Department of Astronomy and Astrophysics, University of Chicago（芝加哥大学天文与天体物理系）；Texas Center for Cosmology and Astroparticle Physics, Weinberg Institute for Theoretical Physics, Department of Physics, The University of Texas at Austin（德克萨斯大学奥斯汀分校物理系温伯格理论物理研究所宇宙线与高能天体物理中心）
Gravitational ultra-relativistic freeze-out during general reheating
Université Paris-Saclay（巴黎萨克雷大学）；CNRS/IN2P3, IJCLab（法国国家科学研究中心/欧洲核子研究委员会粒子物理研究所，IJCLab）；William I. Fine Theoretical Physics Institute, School of Physics and Astronomy, University of Minnesota（明尼苏达大学物理与天文学院威廉·I·芬理论物理研究所）；Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所理论物理部）；China Center of Advanced Science and Technology（中国高等科学技术中心）
B-ball Baryogenesis and the Baryon to Dark Matter Ratio
我们证明了MSSM中的B球衰变可以自然地解决为什么宇宙中重子和暗物质的密度相似的难题。这需要B球在中性伴子LSP的冻结温度（通常为1- 10 GeV）以下的热化和衰变中幸存下来。结果表明，如果重子不对称性起源于MSSM标量势d=6 u^{c} d ^{c} d ^{c} D平坦方向上的夸克凝聚，则这是可能发生的。为了使这一点起作用，膨胀后的再加热温度必须不大于10^3-10^5 GeV。
Leptogenesis and Dark Matter in an Inverse Seesaw from gauged B-L breaking
Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid（马德里自治大学理论物理研究所）；Departamento de Física Matemática, Instituto de Física Universidade de São Paulo（圣保罗大学物理学院数学物理系）；Dipartimento di Fisica e Astronomia, Università di Bologna（博洛尼亚大学物理与天文学系）；INFN, Sezione di Bologna（意大利国家核物理研究所博洛尼部分所）；Institute for Astroparticle Physics (IAP), Karlsruhe Institute of Technology (KIT)（卡尔斯鲁厄理工学院亚原子物理研究所）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯玻尔研究所）
