## Summer Semester 2022

### Quantum Field Theory

USOSThis 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:

### Lie Algebras and Groups

USOSLie 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.

## Winter Semester 2013/2014

### String Theory I

## Summer Semester 2013

### Theoretical Mechanics

## 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.