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SEQUENCE:0
UID:UW-Physics-Event-3838
DTSTART:20151208T213000Z
DTEND:20151208T223000Z
DTSTAMP:20260312T102150Z
LAST-MODIFIED:20151020T203341Z
LOCATION:5280 Chamberlin Hall
SUMMARY:Gauge and fermion preheating and the end of axion inflation\, 
 Theory Seminar (High Energy/Cosmology)\, Evangelos Sfakianakis\, Unive
 rsity of Illinois\, Urbana-Champaign
DESCRIPTION:Axions are attractive candidates for theories of large-fie
 ld inflation that are capable of generating observable primordial grav
 itational wave backgrounds. These fields enjoy shift-symmetries that p
 rotect their role as inflatons from being spoiled by coupling to unkno
 wn UV physics. This symmetry also restricts the couplings of these axi
 on fields to other matter fields. At lowest order\, the only allowed i
 nteractions are derivative couplings to gauge fields and fermions. The
 se derivative couplings lead to the biased production of fermion and g
 auge-boson helicity states during and after inflation. I will describe
  some recent work on preheating in axion-inflation models that are der
 ivatively coupled to Abelian gauge-fields and fermion axial-currents.<
 br>
\n<br>
\nFor an axion coupled to U(1) gauge fields it is found –
 analytically and numerically- that preheating is efficient for a wide 
 range of parameters. In certain cases the inflaton is seen to transfer
  all its energy to the gauge fields within a few oscillations. In most
  cases\, three-dimensional lattice simulations showed that the gauge f
 ields on sub-horizon scales end preheating in an unpolarized state due
  to the existence of strong rescattering between the inflaton and gaug
 e-field modes. <br>
\n<br>
\nCoupling an axion to Majorana fermions le
 ads to the biased production of fermion helicity-states which can have
  interesting phenomenological implications for leptogenesis.
URL:https://www.physics.wisc.edu/events/?id=3838
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