Summer Semester 2022

Quantum Field Theory

One-loop contribution to the anomalous magnetic dipole moment This is the mandatory Quantum Field Theory course of the Master in Theoretical Physics at the University of Wrocław. It is tailored towards master and PhD students who are familiar with

quantum mechanics
electrodynamics
special relativity
quantum electrodynamics.

There are many good books on the subject, four that I like are

[PeskSchr] Peskin, Schroeder: An introduction to quantum field theory
[Ryder] Ryder: Quantum Field Theory
Weinberg: The Quantum Theory of Fields, Volume 1 & 2
Zee: Quantum Field Theory in a Nutshell.

We will follow mostly the first one in the lectures. There will be 2 hours of lectures and 2 hours of seminar each week. Exercises will be posted here a week before the seminar they are discussed in. Please keep in mind that active participation in the seminars is important to pass the course. For more information, please refer to the syllabus (in Polish) or contact me directly.

Important: Students will be assigned to exercise problems by the system described below at the Thursday, 9:00 pm, before the tutorial. Please indicate your preferences by then.

Additional material for the individual lectures, including the exercises which we discuss in the tutorials, is given below:

Reminder of spin 0 and 1/2 fields, notes, exercise

Suppl. reading: [PeskSchr] sections one and two

Please note that there are no exercise assignments for the first seminar. Instead, we continue with the lecture.

Reminder of spin 1 fields and abelian gauge symmetries, notes, exercise

Suppl. reading: [Ryder] sections 3.3 and 4.4

Non-abelian gauge symmetries and Lie groups, notes, exercise

Suppl. reading: [PeskSchr] section 15 except for 15.3 or alternatively [Ryder] sections 3.5 and 3.6

Path integral in quantum mechanics and for the scalar field, notes, exercise

Suppl. reading: [PeskSchr] section 9.1

Generating functional, interactions and Feynman rules, notes, exercise

Suppl. reading: [PeskSchr] section 9.2

Path integral for fermions, Grassmann numbers, chiral anomaly (in the exercise), notes, exercise

Suppl. reading: [PeskSchr] section 9.5

Path integral for spin-1 bosons, ghost fields, notes, exercise

Suppl. reading: [PeskSchr] section 9.4

One loop effects in QED: field-strength renormalisation and self-energy, notes, exercise

Suppl. reading: [PeskSchr] section 7.1

Dimensional regularisation and superficial degree of divergence, notes, exercise

Suppl. reading: Peskin&Schroeder sections 7.5 and 10.1

One-loop renoramlised

\phi^4

theory, notes, exercise

Suppl. reading: [PeskSchr] section 10.2

Renormalisation scale,

\beta

-function, RG flow

Suppl. reading: [PresSchr] sections 12.1-12.3

Renormalised perturbation theory of QED,

g − 2

correction

Suppl. reading: [PresSchr] sections 10.3 and 6.3, Status of the Fermilab Muon g − 2 Experiment

String theory in a nutshell or the one-loop

\beta

-functions of a 2d

\sigma

-model

Suppl. reading: David Tong's lecture notes on String Theory section 7.1, original article Phys.Rev.Lett. 45 (1980) 1057

BRST symmetry, physical Hilbert space

Suppl. reading: [PeskSchr] section 16.2-16.4

Non-Abelian gauge theory, Feynman rules, QCD at one loop

Lie Algebras and Groups

USOS

Lie algebras describe infinitesimal symmetries of physical systems. Therefore, they and their representation theory are extensively used in physics, most notably in quantum mechanics and particle physics. This course introduces semi-simple Lie algebras and the associated Lie groups for physicists. We discuss the essential tools, like the root and weight system, to efficiently work with them and their representations. As on explicit application of the mathematical framework, we discuss Grand Unified Theories (GUT). Moreover, we show how modern computer algebra tools like LieART can significantly help in all explicit computations throughout the course.

A simple example is the visualisation of the root system of $E_6$ projected on the Coxeter plane, which you can see here. If you want to understand how it is created and connected to particle physics, you should take this course. Basic knowledge of core concepts in linear algebra, like vector spaces, eigenvalues and eigenvectors, is assumed. Some good books about the topic are:

Fuchs and Schweigert: Symmetries, Lie Algebras and Representations
Gilmore: Lie Groups, Lie Algebras, and Some of Their Applications
Fulton and Harris: Representation Theory
Georgi: Lie Algebras In Particle Physics: from Isospin To Unified Theories

The article Phys. Rep. 79 (1981) 1 by Slansky and the manual of the LieART package are good references, too.

Note: At multiple occations, we will use Mathematica and it might be a good idea to set it up on your computer. Following the instructions below you should be eventually able to run the notebook, which generates the projection of the $E_6$ root system above.

Introduction and motivation, notes, notebook

Some mathematical preliminaries, notes

Classical matrix groups, notes

Cartan subalgebra, notes

Root system, notes, notebook

Simple root and Cartan matrix, notes

Classification and Dynkin diagrams, notes

Irreducible representations, notes

\mathfrak{su}

(

N

) representations and Young tableaux, notes

Highest weight representations, notes

Characters and self-conjugate modules

Subalgebras

Branching rules

Particle theory and the standard model

The Georgi–Glashow model

Winter Semester 2013/2014

String Theory I

This course introduces bosonic string theory in the elite master course "Theoretical and Mathematical Physics" at LMU Munich. This semester, it is taught by Dieter Lüst. In coordinating with Prof. Lüst, I prepare the excercises, grade them and discuss all solutions with the students in the tutorials. Below is a list of all exercises.

Light-cone coordinates and compact dimensions, exercise

Point particle action and reparameterization, exercise

The 2-sphere, exercise

Polyakov action and conformal transformations, exercise

Classical relativistic string, exercise

Virasoro algebra, exercise

Quantization of the relativistic string, exercise

Path integrals, ghosts and Grassmann numbers, exercise

Conformal field theory, exercise

Vertex operators and the complex plane, exercise

String compactification on the circle, exercise

String compactification on the torus, exercise

D-branes, exercise

Summer Semester 2013

Theoretical Mechanics

An introduction to classical mechanics for bachelor students at the LMU Munich, taught in German by Dieter Lüst. Due to a large number of participating students, there are multiple tutorials for this course, coordinated by James Gray. My responsiblity is to help James in preparing excercises and the exam in German and to give one of the tutorials. A list of all twelve excercises follows.

Vektoren und Kinematik, exercise

Die Newton’schen Axiome, exercise

Erhaltungsgrößen und die Newton’schen Axiome, exercise

Drehimpulserhaltung und Streuung, exercise

Flugbahn und Streuung, exercise

Orbits und der Runge-Lenz Vektor, exercise

Rotierende Koordinatensysteme, exercise

Starre Körper, exercise

Starre Körper und Lagrange-Gleichung erster Art, exercise

Lagrange-Formalismus, exercise

Lagrange-Formalismus II, exercise

Lagrange-Formalismus III, exercise

Generalities

Mathematica

For computations we use Mathematica. It is a very powerful tool with unfortunately a quite high price for a license. Students can get a discount on licenses. If your budget is not sufficient for a student license, you can use the Wolfram Engine for Developers. After creating a Wolfram ID, it can be downloaded for free. The Wolfram Engine implements the Wolfram Language, which Mathematica is based on. But, it lacks the graphical notebook interface. Fortunately, some excellent free software called Jupyter Notebook fills the gap. Both can be connected with the help of Wolfram Language for Jupyter project on GitHub. Getting everything running might require a little bit of tinkering. But in the end, you get a very powerful computer algebra system for free. Finally, you should install LieART by following the "Manual Installation" instructions.

Assignment of problems

Solving the exercise problems for a course is very important. It helps to practice the concepts and ideas introduced during the lecture, and you will also be graded for the solutions you present during the tutorials. But at the same time, one of the most annoying questions for the students and the lecturer is: "Who would like to present his solutions to the next problem?".

Therefore, we use the following system to assign students to problems based on their preferences:

You need to log in with your USOS account (every student at the University of Wrocław should have one). To do so, click on the small closed door in the top left corner of this window and enter your credentials in the window which pops up. The first time you do this, you will be asked to give this website minimal access to your USOS profile.
After a successful login, you can go to your course above and find the new link "manage" after each lecture with an exercise. If you do not see this link, check if you are logged in (the small closed door you clicked in the last step should be slightly open now). Second, verify that the course you are looking at is indeed your course. When the problem still persists, please get in touch with me.
If you click "manage", you will find a list of all the problems that we discuss during the exercises. If problems have not yet been assigned to students, you can indicate your preferences by sorting this list. Entries on the top have the highest priority, while those at the bottom have the lowest. You sort them by drag&drop with either the mouse or your finger if you work with a touchscreen. Once this is done, do not forget to click the "Save" button at the bottom.

You can always come back later and revisit your choice or change it until the assignments are fixed. Once this happens, you will get an email and see the students' names to present the various problems. The backup candidate (the second name) should be ready to take over if required.

Make sure you log out at the end of your session by clicking on the now slightly opened door you arleady used to login.

The assignments made by this system are binding. For every problem you present you can get up to three points. These points are added up and used at the end of the course to calculate your grade. If you cannot present an assigned problem, you will get zero points and put your backup on the spot. Therefore: Please prepare properly and in case of any emergencies, let us know timely. Backup candidates can earn extra points (up to 1.5) by presenting a problem. But they can also lose the same amount if they are not prepared.

Problems are assigned completely automatically after the criteria: Everybody in the course should present the same number of problems. The indicated preferences are taken into account. If several students have the same preferences, the one who submitted them the earliest wins. You do not have to submit any preferences at all. In this case, the system assumes that you do not care which problem you have to present.