PIRSA:18050016

8d gauge anomalies and the topological Green-Schwarz mechanism

García-Etxebarria, I. (2018). 8d gauge anomalies and the topological Green-Schwarz mechanism. Perimeter Institute. https://pirsa.org/18050016

García-Etxebarria, Iñaki. 8d gauge anomalies and the topological Green-Schwarz mechanism. Perimeter Institute, May. 01, 2018, https://pirsa.org/18050016 

          @misc{ pirsa_PIRSA:18050016,
            doi = {10.48660/18050016},
            url = {https://pirsa.org/18050016},
            author = {Garc{\'\i}a-Etxebarria, I{\~n}aki},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {8d gauge anomalies and the topological Green-Schwarz mechanism},
            publisher = {Perimeter Institute},
            year = {2018},
            month = {may},
            note = {PIRSA:18050016 see, \url{https://pirsa.org}}
          }

Iñaki García-Etxebarria Durham University

DOI 10.48660/18050016
Collection
Talk Type Scientific Series
Subject

Abstract

String theory provides us with 8d supersymmetric gauge theories with gauge algebras su(N), so(2N), sp(N), e_6, e_7 and e_8, but no construction for so(2N+1), f_4 and g_2 is known. If string theory is universal in 8 dimensions, this pattern requires explanation. I will show that the theories for f_4 and so(2N+1) have a global gauge anomaly in flat space, while g_2 does not have it. Surprisingly, we also find that the sp(N) theories, arising from example from O7^+ planes in string theory, have a subtler gauge anomaly. This subtler anomaly, in contrast to the one in flat space, could in principle be canceled by a topological analogue of the Green-Schwarz mechanism. I will discuss one simple example of such a generalized anomaly cancellation mechanism in three dimensions, and then explain why the generalized Green-Schwarz term required in 8 dimensions to make the O7^+ consistent is necessarily a more subtle generalization of a Chern-Simons coupling