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SUMMARY:Paths to Solving the Strong CP Problem and the Footprints Left Beh
 ind
DTSTART:20260716T060000Z
DTEND:20260716T070000Z
DTSTAMP:20260704T072800Z
UID:indico-event-18352@indico.global
DESCRIPTION:Speakers: Yuichiro Nakai\n\nWe explore two major approaches to
  the strong CP problem\, the axion solution and spontaneous CP violation (
 SCPV). We first focus on composite axion models\, which provide a compelli
 ng realization of the axion solution but face serious cosmological challen
 ges\, in particular the domain wall problem. We present a new framework ba
 sed on a special embedding of gauge symmetries\, where the domain wall num
 ber is reduced to unity in the ultraviolet theory\, and small instanton ef
 fects induce a controlled bias term that lifts the vacuum degeneracy and a
 llows domain walls to decay without spoiling the axion solution. We also c
 omment on two alternative approaches to the axion domain wall problem. We 
 then turn to the axionless approach based on SCPV\, where CP is an exact s
 ymmetry of the Lagrangian and is broken only spontaneously. In supersymmet
 ric theories\, SCPV can be realized along flat directions and stabilized b
 y supersymmetry-breaking and non-perturbative dynamics\, and the framework
  is compatible with viable cosmology including Affleck–Dine baryogenesis
 . These mechanisms provide distinct paths to resolving the strong CP probl
 em with testable implications.\n\nhttps://indico.global/event/18352/
URL:https://indico.global/event/18352/
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