A tale of two studies: threshold radiation in QCD, and the classical double copy
Abstract
When calculating a fixed order differential cross section in QCD, one must take into
account the contribution of threshold radiation, i.e., soft or collinear radiation produced
in the threshold limit of the kinematic invariants of a given process. However, large
logarithmic terms associated with threshold radiation threaten the stability of the fixed
order theory prediction. A possible antidote to this problem is the resummation of such
terms. Part one of this thesis is concerned with the resummation of a particular class
of large log, the next-to-leading-power (NLP) logs. We investigate the structure and
sources of NLP logs by using the Drell-Yan process as a probe. More specifically, we
consider the case of two real emissions and 1 virtual emission, as well as the case of any
number of real emissions.
The second half of this thesis changes course towards the double copy - a duality
relating gravity and gauge theories. The double copy operates perturbatively, linking
the amplitudes of these theories, as well as the exact solutions of the equations of motion
when considering the classical limit. The double copy package includes biadjoint
scalar theory - a scalar theory that encapsulates much of the information encoded in the
propagators of gravity and gauge theories, but with the benefit of relative simplicity.
We pose the question of whether the double copy operates at a non-perturbative level,
and use biadjoint scalar theory as a probe. We explore monopole solutions in biadjoint
scalar theory, and attempt to match these to monopoles in Yang-Mills theory, using
the Aichelburg-Sexl ultraboost procedure to generate shockwave solutions in aid of this
inquiry. Although the monopoles do not seem to match up, we attain new insights regarding
how Abelian and non-Abelian monopoles can double copy to the same gravity
object.
Authors
Bahjat-Abbas, NCollections
- Theses [4203]