Hopf-Wess-Zumino term in the effective action of the 6d, (2, 0) field theory revisted

We discuss the Hopf-Wess-Zumino term in the effective action of the 6d (2, 0) theory of the type A_{N-1} in a generic Coulomb branch. For such terms, the supergravity calculation could be trusted. We calculate the WZ term on supergravity side and show that it could compensate the anomaly deficit, as is required by the anomaly matching condition. In contrast with the SYM theory, in which each WZ term involves one root e_{i}-e_{j}, here, the typical WZ term involves two roots e_{i}-e_{j} and e_{k}-e_{j}. Such kind of triple interaction may come from the integrating out of the massive states carrying three indices. A natural candidate is the recently proposed 1/4 BPS objects in the Coulomb phase of the 6d (2, 0) theories. The WZ term could be derived from the field theory by the integration out of massive degrees of freedom. Without the 6d (2, 0) theory at hand, we take the supersymmetric equations for the 3-algebra valued (2, 0) tensor multiplet as the prototype to see how far we can go. The H_{3}\wedge A_{3} part of the WZ term is obtained, while the A_{3}\wedge F_{4} part, which is the term accounting for the anomaly matching, cannot be produced by the standard fermion loop integration.Comment: 24 pages, accepted by JHEP; v2: references adde

Twisted Cohomotopy implies level quantization of the full 6d Wess-Zumino term of the M5-brane

The full 6d Hopf-Wess-Zumino term in the action functional for the M5-brane is anomalous as traditionally defined. What has been missing is a condition implying the higher analogue of level quantization familiar from the 2d Wess-Zumino term. We prove that the anomaly cancellation condition is implied by the hypothesis that the C-field is charge-quantized in twisted Cohomotopy theory. The proof follows by a twisted/parametrized generalization of the Hopf invariant, after identifying the full 6d Hopf-Wess-Zumino term with a twisted homotopy Whitehead integral formula, which we establish.Comment: 22 pages; v2 fixes a missing theta7-summand in intermediate formulas and has two remarks added, for clarification; v3 fixes typos and makes the slicing over the homotopy fiber space of chi_8 more explici