Early-Universe Model Building

Theoretical investigations into the evolution of the early universe are an\nessential part of particle physics that allow us to identify viable extensions\nto the Standard Model as well as motivated parameter space that can be probed\nby various experiments and observations. In this white paper, we review\nparticle physics models of the early universe. First, we outline various models\nthat explain two essential ingredients of the early universe (dark matter and\nbaryon asymmetry) and those that seek to address current observational\nanomalies. We then discuss dynamics of the early universe in models of neutrino\nmasses, axions, and several solutions to the electroweak hierarchy problem.\nFinally, we review solutions to naturalness problems of the Standard Model that\nemploy cosmological dynamics.\n