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SUMMARY:Axiverse Lampposts
DTSTART:20260311T133000Z
DTEND:20260311T153000Z
DTSTAMP:20260417T221300Z
UID:indico-event-1729@indico.dfa.unipd.it
DESCRIPTION:Speakers: David Cyncynates (ICTP\, Trieste)\n\nThe string axiv
 erse predicts a unique connection between the high scales approachable onl
 y through theory and the low energies within reach of experimental verific
 ation: a multitude of light\, feebly interacting axions. In order to captu
 re the collective effects of such an axion ensemble\, we model the string 
 axiverse by $N$ coupled axions with a simple assumption: hierarchical axio
 n masses that arise from hierarchical instantons. In this limit\, we find 
 that axion field ranges\, which determine late-time cosmological abundance
 s\, shrink as $1/\\sqrt{N}$ as the number of axions grows. Moreover\, the 
 heaviest modes tend to align with the smallest kinetic eigenvalues\, furth
 er reducing their field ranges. Interactions with the Standard Model (SM) 
 are largely set by the kinetic structure and do not grow with $N$\, which 
 suppresses detection prospects relative to the individual-axion expectatio
 n. The exceptions are the ensemble's lightest and heaviest states as well 
 as the QCD axion\, which incur no such suppression. We further find that c
 oupled axiverse dark matter has parametrically relaxed tuning on initial c
 onditions when produced via long\, low-scale inflation relative to indepen
 dent axions and high-scale inflationary histories. Taken together\, these 
 results sharpen the observational outlook: the most accessible signals typ
 ically come from the QCD axion and from heavy axions that make up small da
 rk matter subcomponents. If light axions have SM interactions independent 
 of QCD\, they can also be within reach of future direct-detection experime
 nts.\n\nhttps://indico.dfa.unipd.it/event/1729/
LOCATION:1/1-2 - Aula "C. Voci" (Dipartimento di Fisica e Astronomia - Edi
 ficio Marzolo)
URL:https://indico.dfa.unipd.it/event/1729/
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