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SUMMARY:Ultra-slow-turn inflation - Ana Achúcarro (Leiden U. &amp\; Basqu
 e U.\, Bilbao)
DTSTART:20260223T130000Z
DTEND:20260223T140000Z
UID:TALK242626@talks.cam.ac.uk
CONTACT:Gonzalo Villa
DESCRIPTION:Multifield inflation models involving ultra-light fields such 
 as moduli and axions  are a generic outcome of string and supergravity c
 osmology. In this talk we consider under what conditions their primordial 
 perturbation spectra may be consistent with observations on the largest (C
 MB) scales.  The usual route is to stabilise the light fields so as to r
 ecover single-field inflation. Another possibility is if massless\, frozen
  isocurvature perturbations can source adiabatic perturbations efficiently
  over many e-folds. I will discuss a third option\, that has emerged more 
 recently\, in which the isocurvature perturbations are tachyonic (unstable
 ) but the instability is shut off by an exponentially decaying turning rat
 e. We call this regime “ultra-slow-turn” (by analogy with the ultra-sl
 ow-roll regime where the first slow roll parameter decays exponentially).
  \n[Based on an upcoming paper with P. Christodoulidis\, J-O. Gong and O.
  Iarygina.]
LOCATION:CMS\, Pav. B\, CTC Common Room (B1.19) [Potter Room]
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