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SEQUENCE:1
UID:UW-Physics-Event-6110
DTSTART:20201009T190000Z
DTEND:20201009T200000Z
DTSTAMP:20260415T003621Z
LAST-MODIFIED:20201005T141921Z
LOCATION:For zoom link\, sign up at: https://groups.google.com/a/g-gro
 ups.wisc.edu/d/forum/theoryseminars/join
SUMMARY:Gravitational wave probes of axion-like particles\, Theory Sem
 inar (High Energy/Cosmology)\, Ben Stefanek\, Mainz Institute for Theo
 retical Physics
DESCRIPTION:Conventional approaches to probing axions and axion-like p
 articles (ALPs) typically rely on a coupling to photons. However\, if 
 this coupling is extremely weak\, ALPs become invisible and are effect
 ively decoupled from the Standard Model. Such particles\, which are vi
 able candidates for dark matter\, can also produce a stochastic gravit
 ational wave (GW) background in the early universe. This occurs if the
  axion couples to a dark gauge boson that experiences a tachyonic inst
 ability when the axion begins to oscillate. This instability exponenti
 ally amplifies vacuum fluctuations of a single dark photon helicity\, 
 resulting in a rapidly time-varying\, anisotropic energy distribution 
 that sources chiral GWs. We identify the regions of ALP parameter spac
 e which may be probed by future GW detectors\, including ground- and s
 pace-based interferometers and pulsar timing arrays. Interestingly\, t
 hese experiments have the ability to probe axions from the bottom up\,
  i.e. in the very weakly coupled regime which is otherwise unconstrain
 ed. A smoking gun for the model is the completely chiral nature of the
  GW peak\, which could be detected by LISA or Einstein Telescope if th
 e signal amplitude is large.
URL:https://www.physics.wisc.edu/events/?id=6110
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