KEK Theory Seminar (Dr. Masato Taki)
After explaining basic background materials, I will introduce a new IIB 5-brane description for the 6d E-string theory that is the world-volume theory on M5-brane probing the end of the world M9-brane. The E-string in our new realization, which is named Tao web, is depicted as spiral 5-branes web equipped with the cyclic structure which is a key to uplifting to 6 dimensions. Utilizing the topological vertex to the 5-brane web configuration enables us to write down a combinatorial formula for the generating function of the E-string elliptic genera. Our Tao web description can be generalized to a wide range of 6d non-Lagrangian SCFTs. In the latter part of this seminar I will show many examples of brane-webs which lead to 6d SCFTs in the strongly-coupled region.