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SEQUENCE:0
UID:UW-Physics-Event-4055
DTSTART:20160209T213000Z
DURATION:PT1H0M0S
DTSTAMP:20240319T082806Z
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.
\n
\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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