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SUMMARY:Modified Microcausality from Perturbation Theory
DTSTART:20260507T100000Z
DTEND:20260507T113000Z
DTSTAMP:20260426T063400Z
UID:indico-event-2435@indico.ifae.es
DESCRIPTION:Speakers: Giordano Cintia\n\nMicrocausality states that field 
 operators commute at spacelike separations. While this property holds dire
 ctly for Lorentz-invariant states\, it becomes more subtle when Lorentz sy
 mmetry is spontaneously broken. In this talk\, I analyze the operatorial c
 ommutator in interacting scalar field theories using the interaction pictu
 re formalism. For theories without derivative interactions\, I show that m
 icrocausality is preserved\, ensuring that the interacting commutator stil
 l vanishes outside the standard Minkowski light cone\, regardless of the s
 tate considered. In contrast\, derivative interactions modify the free-the
 ory commutator by introducing corrections proportional to derivatives of d
 elta functions\, evaluated on the light cone of the free theory. When expe
 ctation values are taken\, these corrections cancel in Lorentz-invariant s
 tates but persist in states where Lorentz symmetry is spontaneously broken
 . I show that these terms are the signal of a perturbative shift in the li
 ght-cone structure of the free theory\, due to interactions. Finally\, I s
 how how this framework can be used to shed light on the notion of light-co
 ne in the presence of dynamical gravity.\n \n \n\nhttps://indico.ifae.es
 /event/2435/
LOCATION:IFAE Seminar Room (In-Person)
URL:https://indico.ifae.es/event/2435/
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