1202.3692 (Piotr Tourkine et al.)

A R^4 non-renormalisation theorem in N=4 supergravity    [PDF]

Piotr Tourkine, Pierre Vanhove

We consider the four-graviton amplitudes in CHL constructions providing
four-dimensional N=4 models with various numbers of vector multiplets. We show
that in these models the two-loop amplitude factorizes a d^2R^4. This implies a
non-renormalisation theorem for the R^4 term, which forbids the appearance of a
three-loop ultraviolet divergence in four dimensions in the four-graviton
amplitude. We connect the special nature of the R^4 term to the U(1) anomaly of
pure N=4 supergravity.

View original: http://arxiv.org/abs/1202.3692