BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Reining in Rampant Instanton Expansions DTSTART;VALUE=DATE-TIME:20210518T010000Z DTEND;VALUE=DATE-TIME:20210518T020000Z DTSTAMP;VALUE=DATE-TIME:20210619T102540Z DESCRIPTION:Axions have remained popular tools both for phenomenology and for studying the nature of hierarchies in quantum gravity---their instanto n-generated effective potentials are generally robust to local radiative c orrections and so they provide a well-controlled arena in which we can stu dy a variety of problems. How flat can we make these potentials? Experienc e\, and some conjectural quantum gravitational constraints\, suggest that we must lose control of the potential's instanton expansion if we try to m ake it too flat. However\, it is unclear what is physically happening in t his limit. Is the theory actually becoming ill-behaved\, or do we just nee d a different way of describing it? I'll show that we lose control of the instanton expansion because states become light somewhere along the axion' s field space\, and I'll provide an alternative description of the effecti ve potential that is useful even when the instanton expansion fails. Thus\ , a rampant instanton expansion represents a failure in our description of the theory\, which can remain well-controlled even when this expansion is not.\n\n LOCATION:zoom meeting URL: END:VEVENT END:VCALENDAR