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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-5197
DTSTART:20191023T200000Z
DTEND:20191023T210000Z
DTSTAMP:20260415T054011Z
LAST-MODIFIED:20191022T191959Z
LOCATION:4274 Chamberlin Hall
SUMMARY:Axion Dark Matter Production and Sub-Structure in Non-Standard
  Cosmologies\, Theory Seminar (High Energy/Cosmology)\, Nikita Blinov\
 , Fermilab
DESCRIPTION:Ultra-violet completions of the Standard Model often featu
 re a modified cosmology before Big Bang Nucleosynthesis. For example\,
  the energy content of the universe prior to this epoch can be dominat
 ed by a non-relativistic particle that eventually decays and reheats t
 he universe at temperatures of a few MeV. This period of early matter 
 domination (EMD) has important consequences for both the amount of dar
 k matter (DM) that is left over\, and for the growth of density pertur
 bations. I will discuss such a cosmology in the context of axion-like 
 particle (ALP) dark matter\, whose non-thermal nature makes it especia
 lly sensitive to these early-universe dynamics. EMD leads to qualitati
 vely different target parameter space for direct detection experiments
 . I will also show that ALP density perturbations grow much faster dur
 ing EMD\, leading to the formation of dense DM clumps\, or minihalos\,
  with characteristic masses below the Earth mass. While extremely rare
 \, Earth encounters with these clumps would lead to enhanced signals i
 n direct detection experiments. These small-scale structures can also 
 be probed with pulsar timing and photometric monitoring of highly magn
 ified extragalactic stars.
URL:https://www.physics.wisc.edu/events/?id=5197
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