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Résumé |
I will present recent work on the study of null line defects in Lorentzian
conformal field theories in various dimensions. I will first establish some
kinematic facts that follow from null lines geometrically preserving a larger set
of conformal isometries than their timelike and spacelike counterparts. This
conformal symmetry, and especially maximal conformal symmetry, is extremely
constraining -- nearly trivializing systems. I will then consider simple examples
from free theories, comparing their results to ultraboosted limits of timelike and
spacelike systems and arguing that shockwave-type solutions are generic. Along the
way, I will argue that a number of physical consistency conditions compel us to
consider defect correlators as distributions on a restricted subspace of Schwartz
test functions. Consequently, we provide a resolution to a longstanding problem of
ultraboosted limits of gauge potentials in classical electromagnetism. |
