R^4 terms in 11 dimensions and conformal anomaly of (2,0) theory

TL;DR

This paper computes a subleading O(N) term in the scale anomaly of the (2,0) theory using AdS_7/CFT_6 correspondence, linking it to R^4 terms in 11D supergravity and exploring its implications for anomaly matching.

Contribution

It identifies the R^4 term responsible for the O(N) contribution to the (2,0) theory's scale anomaly and connects it to known anomaly structures and free theory limits.

Findings

The O(N) anomaly contribution arises from an R^4 term in 11D supergravity.

The total anomaly at N=1 matches that of a free tensor multiplet.

A proposed shift in the anomaly coefficient from 4N^3 to 4N^3 - 3N.

Abstract

Using AdS_7/CFT_6 correspondence we discuss computation of a subleading O(N) term in the scale anomaly of (2,0) theory describing N coincident M5 branes. While the leading O(N^3) contribution to the anomaly is determined by the supergravity action, the O(N) contribution comes from a particular R^4 term (8d Euler density) in the 11-dimensional effective action. This R^4 term is argued to be part of the same superinvariant as the P-odd C_3 R^4 term known to produce O(N) contribution to the R-symmetry anomaly of (2,0) theory. The known results for R-anomaly suggest that the total scale anomaly extrapolated to N=1 should be the same as the anomaly of a single free (2,0) tensor multiplet. A proposed explanation of this agreement is that the coefficient 4N^3 in the anomaly (which was found previously to be also the ratio of the 2-point and 3-point graviton correlators in the (2,0) theory and in the free tensor multiplet theory) is shifted to 4N^3 -3N.