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Résumé |
According to the Swampland idea, quantum gravity effects put severe constraints on
effective field theories
beyond the usual consistency conditions from quantum field theory such as absence
of gauge or gravitational
anomalies. In this talk, we propose such constraints for four-dimensional N=1
supergravities based on consistency
of certain axionic, or EFT, strings. These are certain strings which are
magnetically charged under the axionic components
of the chiral N=1 superfields; their existence follows from the Completeness
Conjecture in quantum gravity.
The key observation is that anomaly inflow from the four-dimensional theory to the
string worldsheet induces anomalies
on the string which must be cancelled by local anomalies on the string. This
results in various quantisation conditions as well as
bounds on the signs of axionic couplings in the supergravity, including the sign
of the Gauss-Bonnet term, and also bounds on the rank of the
gauge group in terms of these Gauss-Bonnet couplings. These constraints can rule
out supergravity theories which
otherwise look perfectly healthy as effective field theories of quantum gravity.
We also test the proposed constraints by comparing them with explicit string
models, in particular with F-theory compactifications to four dimensions. |
