Journée-séminaire de combinatoire

(équipe CALIN du LIPN, université Paris-Nord, Villetaneuse)

Le 20 septembre 2016 à 14h00 en B107, Joseph Ben Geloun nous parlera de : Counting observables of colored tensor models

Résumé : Colored tensor models generate Feynman graphs representing discrete geometries. They form as an interesting approach of quantum gravity where discrete geometries represent quanta of spacetime. The coloring in tensor models improves a lot the topology type of these discrete structures and this helps a lot in their understanding. In my presentation, I will review (in a pedestrian way) their construction and then list basic properties of their observables. Recalling that an observable simply means in this context a convolution or contraction of tensors, observables of colored tensor models map to bi-partite colored graphs. A first question that one can address is can we enumerate these observables? I will explain how such an enumeration is possible and how it has lead us to an intriguing bijection with the counting of branched covers of the 2-sphere.


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