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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2770
DTSTART:20121005T190000Z
DURATION:PT1H0M0S
DTSTAMP:20260305T115019Z
LAST-MODIFIED:20121003T000848Z
LOCATION:5280 Chamberlin
SUMMARY:Three Exceptions for Thermal Dark Matter with Enhanced Annihil
 ation to Gamma Gamma\, Theory Seminar (High Energy/Cosmology)\, Hai-Bo
  Yu\, University of Michigan
DESCRIPTION:Recently\, there have been hints for dark matter (DM) anni
 hilation in the galactic center to one or more photon lines. In order 
 to achieve the observed photon line flux\, DM must have a relatively l
 arge effective coupling to photons\, typically generated radiatively f
 rom large couplings to charged particles. When kinematically accessibl
 e\, direct annihilation of DM to these charged particles is far too la
 rge to accommodate both the DM relic density and constraints from the 
 observed flux of continuum photons from the galactic center\, halo and
  dwarf galaxies. We discuss three exceptions to these obstacles\, gene
 rating the observed line signal while providing the correct relic dens
 ity and evading photon continuum constraints. The exceptions are (i) c
 oannihilation\, where the DM density is set by interactions with a hea
 vier state that is not populated today\, (ii) forbidden channels\, whe
 re DM annihilates to heavier states that are kinematically blocked tod
 ay\, but open in the early Universe\, and (iii) asymmetric DM\, where 
 the relic density is set by a primordial asymmetry. We build simple mo
 dels to realize these scenarios.
URL:https://www.physics.wisc.edu/events/?id=2770
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