Cancelling mod-2 anomalies by Green-Schwarz mechanism with $B_{\mu u}$
Shota Saito, Yuji Tachikawa · SciPost Physics · 2025
We study if and when mod-2 anomalies can be canceled by the Green-Schwarz mechanism with the introduction of an antisymmetric tensor field B_{\mu u} B μ ν . As explicit examples, we examine SU(2) S U ( 2 ) and more general Sp(n) S p ( n ) gauge theories in four and eight dimensions. We find that the mod-2 anomalies of 8d \mathcal{N}=1 𝒩 = 1 Sp(n) S p ( n ) gauge theory can be canceled, as expected from it having a string theory realization, while the mod-2 Witten anomaly of 4d SU(2) S U ( 2 ) and Sp(n) S p ( n ) gauge theory cannot be canceled in this manner.