Speaker
Description
In higher derivative (HD) theories, a new kind of infrared divergences emerges from loop integrals. While in ordinary 2-derivative theories in d=4 IR divergencies are associated with the emission of soft or collinear particles by almost on-shell external legs, in HD theories IR divergencies are also observed in far off-shell processes. For this reason, the usual procedure of reabsorbing IR effect in "dressed" IR-safe asymptotic states seems to fail in this case. These kinds of new IR enhancements have been treated in different ways during recent years, in particular within the context of quadratic gravity. We will discuss how these IR divergences are generated, showing in which way they are intrinsically different with respect to the well-known two derivative case. Then we will see how symmetries and some particular cancellations peculiar to higher derivative theories can help in defining well-defined scattering amplitudes.
| Affiliation | Heidelberg university |
|---|---|
| Career status | Postdoc |