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Ultraviolet Behavior of Supergravity Amplitudes

Abstract

In this manuscript, we detail three recent calculations

addressing the ultraviolet behavior of supersymmetric quantum

gravity. First, we revisit the classic calculation of the two-loop

pure gravity divergence. We argue that the $\frac{1}{\epsilon}$

divergence is regulator and duality dependent. In its place, we

propose that examining the running of the scaling parameter,

$\log \mu$, is a duality and regulator independent approach to

assessing gravity divergences in four dimensions. We explicitly

calculate the $\log \mu$ coefficient at two loops for gravity with

any particle content, explicitly verifying the divergences for pure

gravity, and the finiteness for supersymmetric gravities. Second,

we analyze fully-integrated $\NeqFour$ supergravity at one loop

using the double copy. We find that there are evanescent effects at

one loop that come directly from evanescent terms in

pure-Yang--Mills. Using this observation, we lay the groundwork for

deeper analysis of the $U(1)$ anomaly with respect to the observed

evanescent behavior. Finally, we tackle the long-standing question

of the critical dimension of $\NeqEight$ supergravity at five loops.

We construct an integrand using the generalized double copy, expand

the integrand in large loop momentum, and reduce the resulting

integrals using $\mathfrak{sl}(L)$ integration-by-parts relations.

This procedure yields a critical dimension of $d_c = 24/5$.

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