Looking for advice for learning QFT

[Haorong Wu]

Hello. I am trying to learn quantum field theory. I am crazy about it but I have some problems in my study.

I use An Introduction to Quantum Field Theory by Peskin and Schroeder. It is said that the book is easier to learn than other books. However, I have to spend a lot of time in computing and deriving equations along the context.

For example, $\left ( \partial ^2 +m ^2 \right )\phi ^{'} \left ( x \right )= \left [ \left ( \Lambda ^{-1}\right )^{\nu} _{\mu} \partial _\nu \left ( \Lambda ^{-1}\right ) ^{\sigma \mu} \partial_\sigma +m^2 \right] \phi \left ( \Lambda ^{-1} x\right )$ where $\phi^{'} \left ( x \right ) =\phi \left ( \Lambda ^{-1} x \right )$.

It costed me more than an hour to get the expression on the right side. Should I focus on those physical pictures and leave the mathematical part aside?

I have learned the graduate level's quantum mechanics and group theory. Should I learn other prerequisite courses fist?

Did you feel difficult when you first learned it?

Thanks!

 

[PeroK]

Hello. I am trying to learn quantum field theory. I am crazy about it but I have some problems in my study.

I use An Introduction to Quantum Field Theory by Peskin and Schroeder. It is said that the book is easier to learn than other books. However, I have to spend a lot of time in computing and deriving equations along the context.

For example, $\left ( \partial ^2 +m ^2 \right )\phi ^{'} \left ( x \right )= \left [ \left ( \Lambda ^{-1}\right )^{\nu} _{\mu} \partial _\nu \left ( \Lambda ^{-1}\right ) ^{\sigma \mu} \partial_\sigma +m^2 \right] \phi \left ( \Lambda ^{-1} x\right )$ where $\phi^{'} \left ( x \right ) =\phi \left ( \Lambda ^{-1} x \right )$.

It costed me more than an hour to get the expression on the right side. Should I focus on those physical pictures and leave the mathematical part aside?

I have learned the graduate level's quantum mechanics and group theory. Should I learn other prerequisite courses fist?

Did you feel difficult when you first learned it?

Thanks!

I'm learning QFT as well. I have QFT for the Gifted Amateur and I have been watching Tobias Osborne's lectures on YouTube:



The Gifted Amateur book is good, but the exercises are poor. I haven't tried Peskin and Schroeder but it has a good reputation.

I got a copy of QFT in a Nutshell by Zee, but I couldn't make any sense of it at all. Perhaps, despite its good reviews, it's really a book for those who already know QFT?

David Tong's notes look good.

My observations are:

1) It's an advanced subject. The amount of mathematics to fill in the gaps is far larger than I've encountered before. You have to strike a balance between learning the material and getting bogged down trying to follow all the mathematics first time round.

2) Any subsidiary material (EM, Noether's theory, the Dirac equation etc.) must be learned separately. The material in the QFT books themselves (even if the author thinks otherwise) is never enough to pick up the material. Not for me anyway. If you find that you are getting lost, look for a text that covers the material in more detail. For example:

Noether's Theorem by Neuenschwander

Elementary Particles by Griffiths - this has a lot of material that is presented at the senior undergraduate level with lots of detail and problems. I found it excellent preparation for QFT.

3) Be prepared to take a break, learn more background material then come back to it.

4) Especially without a tutor or other resources it's a real challenge. Don't be too hard on yourself if you find it hard. It is hard!

 

[Haorong Wu]

Thanks, @ PeroK.

The lectures are great. The professor seems to speaking English, but the notes on the blackboard appear not in English. Should I worry about that?

1. I have not read Zee's book, but I have read his book about group theory. In my opinion, professor Zee would like to concentrate on physical images. I may not like that style very much while others may say he provides group theory and QFT in an easier way.

2. I think I will go through some part of the book first, then watch the lectures, and then carefully go through again. I must say, QFT is so interesting!

3. It seems I have much to learn. I will find some copies of them. Could you suggest a textbook about Dirac's equation. I only learn it in the relativistic quantum mechanics part in Sakurai's book.

 

[PeroK]

Thanks, @ PeroK.

The lectures are great. The professor seems to speaking English, but the notes on the blackboard appear not in English. Should I worry about that?

3. It seems I have much to learn. I will find some copies of them. Could you suggest a textbook about Dirac's equation. I only learn it in the relativistic quantum mechanics part in Sakurai's book.

The lectures are in English, but at a German university. The German on the board is from a previous lecture. The lectures shoudl be a good supplement to a textbook: at least to hear someone teach it.

I learned about the Dirac equation from Griffith's particle physics book.

 

[Haorong Wu]

The lectures are in English, but at a German university. The German on the board is from a previous lecture. The lectures shoudl be a good supplement to a textbook: at least to hear someone teach it.

I learned about the Dirac equation from Griffith's particle physics book.

Thanks PeroK. I believe I have more confidence now.

 

[weirdoguy]

Out of all QFT books that I have seen so far, Klauber's Student Friendly Quantum Field Theory is the easiest and most didactical one. He really delves into most of the calculations in great details. You can find parts of this book on its website: http://www.quantumfieldtheory.info/
For me, the biggest disadvantage is that it is written in MS Word, not in LateX Klauber is working on the second part dealing with Standard Model, can't wait.

 

[Haorong Wu]

Out of all QFT books that I have seen so far, Klauber's Student Friendly Quantum Field Theory is the easiest and most didactical one. He really delves into most of the calculations in great details. You can find parts of this book on its website: http://www.quantumfieldtheory.info/
For me, the biggest disadvantage is that it is written in MS Word, not in LateX Klauber is working on the second part dealing with Standard Model, can't wait.

Thanks, @weirdoguy . I will try it. Look great.

 

[radium]

Another good text to learn from is Quantum Field Theory and the Standard Model, although it’s a bit biased toward particle phenomenology. The exercises are very helpful for learning to calculate scattering amplitudes/cross sections

 

[haushofer]

I got a copy of QFT in a Nutshell by Zee, but I couldn't make any sense of it at all. Perhaps, despite its good reviews, it's really a book for those who already know QFT?

Yes, it is.