Beyond the Thermal WIMP Paradigm: Theoretical Motivations and Experimental Signatures

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This award funds the research activities of Professor Rouzbeh Allahverdi at the University of New Mexico. We know from observations that only 15% of the matter in the universe is described by the Standard Model of particle physics, while 85% is made of dark matter (DM). However, the nature and origin of DM remains one of the most profound problems at the interface of particle physics and cosmology. A whole array of direct- and indirect-detection experiments, combined with the successful running of the Large Hadron Collider, will help us discover the DM and establish its particle-physics origin. The complementary information provided by these experiments will also play a crucial role in explaining the DM content of the universe. The research funded by this award will study theoretical models and observational signatures of DM production mechanisms beyond the dominant paradigm based on the notion that the DM consists of weakly interacting massless particles. Research in this area thus advances the national interest by promoting the progress of science in one of its most fundamental directions: the discovery and understanding of new physical law. The research funded by this award will also have significant broader impacts. Professor Allahverdi will involve graduate and undergraduate students in his research, and thereby provide critical training to junior physicists beginning research in this field. The PI will additionally bring his results to a broader audience through job shadowing and mentorship of high-school students, as well as by visiting schools and giving public lectures. More technically, the research supported by this award focuses on scenarios of non-thermal DM production having a two-fold goal. First, the PI wishes to study novel theoretical models and distinct experimental signals of non-thermal DM. In several extensions of the Standard Model, the DM is produced in a non-thermal fashion. Second, the PI wishes to explore interesting connections between primordial black holes (PBHs) and non-thermal DM that can arise in a universe with non-standard thermal history. To achieve these objectives, Professor Allahverdi will build new particle-physics models of non-thermal DM, test their observational signals via DM indirect-detection experiments and structure-formation data, and examine consequences of possible connections between PBHs and DM in these models. These investigations will help us determine the theoretical origin of DM and its embedding within a fundamental theory. They will also enable us to use DM as a window to the thermal history of the universe when it was only a tiny fraction of a second old. This is far earlier than that provided by the current observational probes involving the cosmic microwave background or Big-Bang nucleosynthesis.