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SUMMARY:How Quantum Gravity Avoids Generalized Global Symmetries - Irene V
 alenzuela (Harvard)
DTSTART:20210513T130000Z
DTEND:20210513T140000Z
UID:TALK159079@talks.cam.ac.uk
CONTACT:Pietro Benetti Genolini
DESCRIPTION:The Swampland program aims to determine the constraints that a
 n EFT must satisfy to be consistent with a UV completion in quantum gravit
 y. One of the most important proposed constraints is the absence of global
  symmetries\, meaning that any global symmetry must be gauged or broken. I
 n this talk\, I will discuss a class of generalized global symmetries\, wh
 ich we call “Chern-Weil global symmetries\,” that arise ubiquitously i
 n gauge theories. The Noether currents of these Chern-Weil global symmetri
 es are given by wedge products of gauge field strengths and their conserva
 tion follows from Bianchi identities\, so they are not easy to break. Howe
 ver\, exact global symmetries should not be allowed in a consistent theory
  of quantum gravity\, and how quantum gravity avoids them can teach us man
 y things about the physics of UV consistent EFTs. In particular\, I will e
 xplain how many familiar phenomena in string theory\, such as axions\, Che
 rn-Simons terms\, worldvolume degrees of freedom on extended objects\, and
  branes ending on or dissolving in other branes\, can be interpreted as co
 nsequences of the absence of Chern-Weil symmetries\, suggesting that they 
 might be general features of quantum gravity. Finally\, I will also show h
 ow the absence of non-invertible global symmetries is in 1-to-1 correspond
 ence with a complete charged spectrum for compact gauge groups.
LOCATION:Online (Zoom)
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