String-based methods in perturbative gravity

Proof of gravity and Yang-Mills amplitude relations

“…It might be interesting to take a fresh look at string-based techniques such as those discussed in ref. [32]. We believe that it could be useful to consider our relations from string theory along the line of [33].…”

Infinities within graviton scattering amplitudes

“…) Recently developments have been made in the calculation of on-shell amplitudes using string inspired techniques and the Cutkosky rules. These have enabled new results to be obtained both in QCD [8] and perturbative quantum gravity [9,10]. In this paper we show how these techniques may be used to detect the effect of the counter terms in the oneloop amplitudes -and in fact extract their coefficient.…”

Perturbative expansion ofN<8Supergravity

“…Considering the rational terms, R n , the existence of an overall d eff that ensures that the bubble coefficients vanish would also ensure the vanishing of R n . Additionally, power counting in the string-based rules [28,29] gives R 4 = R 5 = 0, and if we assume R n could be recursively generated from R n−1 , this would be sufficient to ensure R n = 0 for all n.…”

“…The traditional expectation within supergravity theories is that cancellation between particle types within a supermultiplet reduces the degree of the loop momentum polynomial from 2m to d eff = 2m − r, where r depends upon the degree of supersymmetry. For maximal supergravity r = 8 [28,29] is manifest within the "string-based rules" method. However the no-triangle hypothesis indicates that further cancellations arise, resulting in d eff = m − 4.…”