BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Maria Mylova: "Gauge fixing in open quantum systems"
DTSTART:20260508T120000Z
DTEND:20260508T130000Z
DTSTAMP:20260601T233800Z
UID:indico-event-17970@indico.global
DESCRIPTION:Understanding how to gauge-fix open quantum field theories is 
 essential for building consistent open frameworks for cosmology and gravit
 y\, where gauge symmetry must coexist with dissipation and noise and decoh
 erence. I will present our recent work developing explicit top-down constr
 uctions of open effective field theories (EFTs) for gauge degrees of freed
 om\, with particular emphasis on the role of gauge fixing. We implement BR
 ST quantisation on the Schwinger-Keldysh contour and show that the in-in b
 oundary conditions reduce the doubled global BRST symmetry to a single dia
 gonal copy. This diagonal BRST symmetry is nevertheless sufficient to guar
 antee that the influence functional remains gauge invariant under two inde
 pendent gauge transformations\, retarded and advanced\, independently of t
 he choice of initial state\, the presence of symmetry-breaking phases\, an
 d whether the gauge theory is Abelian or non-Abelian. I will also remark t
 hat once a consistent quantisation scheme is chosen\, the Schwinger-Keldys
 h path integral is uniquely determined\, and with it the rules that constr
 ain the construction of open EFTs.  I will conclude by outlining bottom-u
 p implications\, and how these principles provide a systematic route to ca
 usal\, gauge-invariant open EFTs suitable for cosmological and gravitation
 al applications.\n\nhttps://indico.global/event/17970/
URL:https://indico.global/event/17970/
END:VEVENT
END:VCALENDAR