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SUMMARY:Ryan Plestid\, "Topical seminar: Manifest gauge invariance and old
 -fashioned perturbation theory"
DTSTART;VALUE=DATE-TIME:20260429T080000Z
DTEND;VALUE=DATE-TIME:20260429T093000Z
DTSTAMP;VALUE=DATE-TIME:20260428T033720Z
UID:indico-event-8555@indico.ific.uv.es
DESCRIPTION:When dealing with bound states (e.g.\, atoms or nuclei) many c
 alculations are most efficiently carried out using old-fashioned perturbat
 ion theory. It is difficult\, however\, to see how gauge invariance manif
 ests at the level of the amplitude (this is related to the non-conservatio
 n of energy in OFPT). \n\nIn this talk I will explain how a partial-fract
 ion trick can reorganize amplitudes into a form that is manifestly gauge i
 nvariant. Remarkably\, when applied to the Compton tensor\, the resulting
  amplitude decomposes into four separate gauge invariant pieces that are n
 aturally organized around a heavy-mass expansion. I will comment on poten
 tial implications for atomic\, nuclear\, and hadronic physics applications
  involving QED. \n\nhttps://indico.ific.uv.es/event/8555/
LOCATION:Universe 1001-Primera-1-1-1 - Paterna. Seminario
URL:https://indico.ific.uv.es/event/8555/
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