Grothendieck stacks in QFT, did not know about it. This is wild stuff: https://people.math.umass.edu/~mirkovic/0.SEMINARS/1.QFT/C.Costello/Perturbative.QFT.pd

Grothendieck stacks in QFT, did not know about it. This is wild stuff: https://people.math.umass.edu/~mirkovic/0.SEMINARS/1.QFT/C.Costello/Perturbative.QFT.pdf https://people.math.umass.edu/~mirkovic/0.SEMINARS/1.QFT/C.C... funny names: a Leonard Cohen writing about an Costello (but Kevin Costello not Elvis Costello)