Particle Physics Origin of Dark Matter and Cosmological History

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This award funds the research activities of Professor Rouzbeh Allahverdi at the University of New Mexico Department of Physics and Astronomy. We know from observations that only 15% of the matter in the universe is described by the Standard Model (SM) of particle physics, while 85% is made of Dark Matter (DM). However, the nature and origin of DM remains as one of the most profound problems at the interface of particle physics and cosmology. The successful running of the Large Hadron Collider (LHC) has put us on the verge of discovering new physics beyond the SM. This, combined with a whole array of direct and indirect detection experiments, 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 shedding light on the cosmological history of the early universe. The research funded by this award will be to help establish the nature of Dark Matter by using complementary signals from different experiments, and to determine its origin. It will also study the reason for the numerical coincidence that the amount of visible matter and dark matter are not too different, and will study possible interactions between Dark Matter and neutrinos. 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 outreach his results to a broader audience by giving public lectures and visiting schools.The research supported by this award has a three-fold goal. First, by using complementary signals from different experiments to determine the thermal or non-thermal origin of DM. In several extensions of the SM, the DM is produced non-thermally. Second, to investigate models that can address the baryon-DM coincidence puzzle, since in general the densities of baryons and DM can be widely different (since they are produced at very different epochs). Third, to probe possible connections between the DM and neutrinos, including possible sensitivity to the Dirac or Majorana nature of neutrinos. To achieve these objectives, Professor Allahverdi studies various particle physics models of DM in light of data from indirect detection searches, and examines their testable predictions for collider and direct detection experiments. These investigations will help determine the deeper theoretical origin of the DM sector 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 a tiny fraction of a second old. This is far earlier than that provided by current observational probes, namely the Cosmic Microwave Background (CMB) and the Big Bang Nucleosynthesis (BBN).