Chapter 6
Summary
Abstract While the field of jet substructure is still relatively young, it has led to
a myriad of studies and measurements at the LHC. These probe regions which are
inaccessible with other methods, emphasising the importance of jet substructure
techniques. These techniques will be refined and improved in the years to come,
resulting in indispensable tools for experimental studies.
Jet substructure has permeated a multitude of analyses at the LHC. These range from
searches for new physical phenomena, a better understanding of the strong force and
top quark production, to studies of the Higgs boson. Jet substructure analyses of LHC
data have been facilitated by dedicated experimental studies of the detector response
and elaborate theoretical calculations, made possible by the precise formulation of
jet substructure algorithms. Many of the results published by the ATLAS and CMS
Collaborations have profited from these developments, either improving the precision
or enabling the execution of analyses in the first place.
Numerous theoretical and experimental challenges in the field of jet substructure
make the successful application of these techniques a remarkable achievement. On
the theory side, either fixed-order perturbative calculations with virtual corrections
and matched parton showers are needed to achieve sufficient accuracy for a reliable
prediction of jet substructure observables; or all-order resummations of the leading
and subleading effects need to be performed. Insights into the advantages and limitations of one or the other approach can be gained by comparing results from different
calculations. An additional complication arises from non-perturbative effects, such
as hadronisation and particle decays, which can lead to sizeable corrections that
are difficult to estimate from first principles. These can be approximated through
corresponding models implemented in event generators or non-perturbative parameters in analytic calculations, leading to distortions of distributions. In some models,
these corrections are intricately connected with the underlying event, which also has
a perturbative and a non-perturbative part. Only by simulating all of these effects,
realistic estimates of the performance of jet substructure algorithms can be obtained,
and the estimation of fundamental SM parameters from jet substructure measurements becomes feasible. On the experimental side, an excellent understanding of
the reconstruction efficiencies of all particles produced in the collision is needed
© Springer Nature Switzerland AG 2021
R. Kogler, Advances in Jet Substructure at the LHC, Springer Tracts
in Modern Physics 284, https://doi.org/10.1007/978-3-030-72858-8_6
209
Summary
Abstract While the field of jet substructure is still relatively young, it has led to
a myriad of studies and measurements at the LHC. These probe regions which are
inaccessible with other methods, emphasising the importance of jet substructure
techniques. These techniques will be refined and improved in the years to come,
resulting in indispensable tools for experimental studies.
Jet substructure has permeated a multitude of analyses at the LHC. These range from
searches for new physical phenomena, a better understanding of the strong force and
top quark production, to studies of the Higgs boson. Jet substructure analyses of LHC
data have been facilitated by dedicated experimental studies of the detector response
and elaborate theoretical calculations, made possible by the precise formulation of
jet substructure algorithms. Many of the results published by the ATLAS and CMS
Collaborations have profited from these developments, either improving the precision
or enabling the execution of analyses in the first place.
Numerous theoretical and experimental challenges in the field of jet substructure
make the successful application of these techniques a remarkable achievement. On
the theory side, either fixed-order perturbative calculations with virtual corrections
and matched parton showers are needed to achieve sufficient accuracy for a reliable
prediction of jet substructure observables; or all-order resummations of the leading
and subleading effects need to be performed. Insights into the advantages and limitations of one or the other approach can be gained by comparing results from different
calculations. An additional complication arises from non-perturbative effects, such
as hadronisation and particle decays, which can lead to sizeable corrections that
are difficult to estimate from first principles. These can be approximated through
corresponding models implemented in event generators or non-perturbative parameters in analytic calculations, leading to distortions of distributions. In some models,
these corrections are intricately connected with the underlying event, which also has
a perturbative and a non-perturbative part. Only by simulating all of these effects,
realistic estimates of the performance of jet substructure algorithms can be obtained,
and the estimation of fundamental SM parameters from jet substructure measurements becomes feasible. On the experimental side, an excellent understanding of
the reconstruction efficiencies of all particles produced in the collision is needed
© Springer Nature Switzerland AG 2021
R. Kogler, Advances in Jet Substructure at the LHC, Springer Tracts
in Modern Physics 284, https://doi.org/10.1007/978-3-030-72858-8_6
209