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DTSTAMP:20260921T003519Z
LAST-MODIFIED:20200127T164400Z
DTSTART:20200219T211500Z
DTEND:20200219T221500Z
UID:event2265@bu.edu
URL:http://physics.bu.edu/internal/events/show/2265
SUMMARY:Conformal Freeze-in
DESCRIPTION:Featuring Sungwoo Hong\, Cornell University\n\nPart of the HET 
	Seminar Series.\n\nConventionally\, the main focus for the cosmic evolution
	 of our universe has been on descriptions in terms of particles: dark matte
	r (DM) as massive particle\, and dark radiation\, if existing at all\, in t
	he form of massless or very light particle. In this talk\, I will discuss a
	 scenario where conformal field theory (CFT) plays a crucial role in cosmol
	ogy\, especially production of naturally light dark matter. When the Standa
	rd Model (SM) couples to a sector of CFT\, I will argue that in the regime 
	where only the SM sector gets reheated\, the energy density of the CFT sect
	or is populated via energy injection from the SM (conformal freeze-in) and 
	can be reliably computed. Such CFT energy density\, redshifting like a radi
	ation\, will not account for DM unless somehow a mass gap is generated in t
	he CFT. Remarkably\, such a gap scale is dynamically generated due to phase
	 transitions of SM: electroweak and QCD. In this way\, DM energy today is p
	roduced in the early universe when it is not in gapped particle state\, but
	 a CFT state. Moreover\, DM mass scale consistent with observed relic densi
	ty and other observational constraints (mostly bullet cluster and warm dark
	 matter bounds) turns out to be less than MeV. Therefore\, conformal freeze
	-in provides a framework for naturally light DM. I will discuss theoretical
	 and phenomenological aspects of cosmology with conformal freeze-in.
LOCATION:PRB 595\, 3 Cummington Mall\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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