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VERSION:2.0
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SEQUENCE:0
UID:UW-Physics-Event-4055
DTSTART:20160209T213000Z
DURATION:PT1H0M0S
DTSTAMP:20260420T001405Z
LAST-MODIFIED:20160208T174227Z
LOCATION:5280 Chamberlin Hall
SUMMARY:High-Scale Axions without Isocurvature from Inflationary Dynam
 ics\, Theory Seminar (High Energy/Cosmology)\, Dr. Jack Kearney \, Fer
 milab
DESCRIPTION:If the PQ-breaking scale f is larger than the inflationary
  Hubble scale HI\, the PQ symmetry is broken during inflation.  In the
  most straightforward models\, this gives rise to a light axion field 
 during inflation\, which acquires isocurvature fluctuations.  Such flu
 ctuations are very stringently constrained by current CMB measurements
 ---in fact\, supposing the near-future observation of primordial tenso
 r modes (i.e.\, a measurement of a non-zero scalar-to-tensor ratio r\,
  indicating a high inflationary scale)\, these constraints would exclu
 de simple models of QCD axion dark matter in which f is larger than HI
 .  This is particularly problematic for the near-Planckian values of f
  favored by\, for instance\, string theory.<br>
\n<br>
\nA variety of 
 solutions have been proposed to "resurrect" high-scale axions.  Many s
 eek to leverage inflationary dynamics to modify the behavior or potent
 ial of the PQ field during inflation in order to suppress isocurvature
 .  However\, inflation and the axion potential are both very fragile\,
  and readily disrupted by additional interactions or couplings. As suc
 h\, it is important to carefully consider the viability of influencing
  the PQ field via inflationary dynamics\; in other words\, can this re
 ally be accomplished without messing up either inflation or the soluti
 on to the strong CP problem?  In this talk\, I'll discuss the variety 
 of issues that can arise in these constructions\, and highlight the st
 eps one must take to build a viable model.
URL:https://www.physics.wisc.edu/events/?id=4055
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