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Master Topics for winter term 2022/2023
Click on the topic titles below to see more details.
To apply, follow the instructions
here,
where you can also find topics from the other members of
our institute.
The slides of that presentation can be found here.
In order to discuss the topics in more detail, visit this zoomroom on 30 June 2022 at 1pm.
The gradientflow formulation of QCD
The gradient flow is a concept which provides a potential bridge between
perturbative and nonperturbative physics.
The crucial parameter switching between these two regimes is
the flow time t.
In this project, you will learn the concepts of the gradient flow
and develop methods to extrapolate the perturbative smallt region
to the nonperturbative larget regime. This will help to combine
perturbative and lattice results for the determination of
fundamental QCD parameters.
There are several topics that can be worked on during a master's thesis,
among them the definition of QCD ghosts at finite flow time, or the asymptotic expansion in the limit
of large flow times.
Related publications from our group:

R.V. Harlander and F. Lange,
The effective electroweak Hamiltonian
in the gradientflow formalism
Phys. Rev. D 105 (2022) L071504 [arXiv:2201.08618]

R.V. Harlander, F. Lange, T. Neumann,
Hadronic vacuum polarization using gradient flow
JHEP 08 (2020) 109
[arXiv:2007.01057]

R.V. Harlander, Y. Kluth, and F. Lange,
The twoloop energymomentum tensor within the gradientflow formalism
Eur. Phys. J. C 78 (2018) 944
[err. ibid. C79 (2019) 858]
[arXiv:1808.09837]

J. Artz, R.V. Harlander, F. Lange, T. Neumann, and M. Prausa,
Results and techniques for higher order calculations within the gradient flow formalism
JHEP 06 (2019) 121
[err. ibid. 10 (2019) 032]
[arXiv:1905.00882]

R.V. Harlander and T. Neumann,
The perturbative QCD gradient flow to three loops
JHEP 06 (2016) 161
[arXiv:1606.03756]
Examples for previous master's theses on this topic:
 Janosch Borgulat (April 2022, RWTH Aachen)
Towards the Full EnergyMomentum Tensor in the Gradient Flow Formalism

Yannick Kluth
(September 2018, RWTH Aachen)
Gradient Flow and the EnergyMomentum Tensor

Fabian Lange
(September 2017, RWTH Aachen):
The Perturbative Gradient Flow at Higher Orders

Johannes Artz
(June 2017, RWTH Aachen):
Automatic approach to the perturbative gradient flow
Effective Field Theories to arbitrary orders
Effective Field Theories can describe physics beyond the Standard Model in a
generic way. Their construction is algorithmic, but very
cumbersome.
In this project, you will develop an algorithm for transformations between different
operator bases for EFTs. This will be
useful for the interpretation of data collected at the LHC and
future colliders, in particular in the light of possible new discoveries.
Previous master's theses on this topic:
 Tim Kempkens (October 2021, RWTH Aachen)
Automated Generation of EFT Operators
 Joshua Rosaler (June 2020, RWTH Aachen)
EFTGen: An Algorithm for Automatic Generation of Higher Dimensional Operators in Effective Field Theory
Some literature:
Renormalization of Effective Field Theories
Effective Field Theories are a way to parametrize unknown physics.
A proper theoretical description requires the renormalization of the
higherdimensional operators at higher orders in perturbation theory.
In this project, you will learn the concepts of Effective Field Theories
and operator renormalization. You will develop a method to systematically
determine the renormalization matrix to higher orders in perturbation theory.
Previous master's theses on this topic:
 Joshua Schophoven (November 2020, RWTH Aachen)
Methods for Higher Order Renormalisation of
Quantum Field Theories
Some literature:
Higgs production at the LHC
The Higgs mechanism of the Standard Model is the minimal implementation of
spontaneous symmetry breaking. A careful study of the underlying
phenomenology may shed light into regions beyond the Standard Model.
In this project, you will build on long experience of our group
in this field. You will theoretically study the production mechanisms of
Higgs bosons beyond the Standard Model, in particular supersymmetric models,
2Higgsdoublet models, or effective field theories.
Related publications from our group:

R.V. Harlander, J. Klappert, S. Liebler, and L. Simon,
vh@nnlov2: New physics in Higgs Strahlung
JHEP 05 (2018) 089
[arXiv:1802.04817]

R.V. Harlander, S. Liebler, and H. Mantler,
SusHi Bento: Beyond NNLO and the heavytop limit
Comput. Phys. Commun. 212 (2017) 239257
[arXiv:1605.03190]

R.V. Harlander,
Higgs production in heavy quark annihilation through nexttonexttoleading order QCD
Eur. Phys. J. C 76 (2016) 252
[arXiv:1512.04901]

R.V. Harlander, S. Liebler, and H. Mantler,
SusHi: A program for the calculation of Higgs production in gluon fusion and bottomquark annihilation in the Standard Model and the MSSM
Comput. Phys. Commun. 184 (2013) 16051617
[arXiv:1212.3249]
Examples for previous master's theses on this topic:
 Sebastian Rhode (April 2019), Higgs Production in Gluon Fusion with HigherDimensional Operators
 Lukas Simon (October 2018), CPmixing effects in HiggsStrahlung
last updated on Jun 29, 2022 by RH
