Where Can I Continue Learning QFT on My Own?

[vanesch]

Ive seen requirements to take relativistic qm before qft

Well, can somebody explain me what that IS, relativistic QM ? (and not quantum field theory!)

cheers,
Patrick.

 

[dextercioby]

Dirac's original 1928 theory.4-component wavefunction...That famous chapter in Messiah's book for example.Or Davydov's.

Daniel.

 

[vanesch]

Dirac's original 1928 theory.4-component wavefunction...That famous chapter in Messiah's book for example.Or Davydov's.

Or the first book of Bjorken and Drell... but does it still make sense to study that ?

 

[dextercioby]

Of course.QED brings refinements to Dirac's theory of H atom,but still Gordan-Fock's formula is the one to count on.

It's not fair to jump from Balmer's formula to vacuum polarization correction to 2s and 2 p levels...

And if u add the $$\frac{v^{2}}{c^{2}}$$ approximation,Pauli's hamiltonian and the rigurous deduction of the terms one uses in perturbation theory...

There are reasons to still study Dirac's theory.

Daniel.

 

[baka]

Hi, I'm planning to buy some of QFT books.
Peskin would be my first choice. But I don't think that would be enough for me. Which one do u think will be better for accompany it?
Zee or Bailin&Love or Michio Kaku?

Btw anyone know any good classical field book as well? Cause I'm going to learn both subjects at the same time.

Thanks

 

[Haelfix]

Zee's book is something you can read start to finish on an airplane or something. It bypasses a lot of nitty gritty details and just outputs results, and does it in a very clear fashion. It leaves you wanting more at the end, a lot of it is just seemingly pulled out of the air, and you might be mistaken into thinking QFT is an easy subject.

Its great though as you familiarize yourself with the lingo, the notation and the equations as well as getting some good intuitive idea of how things come about.

Peskins book is also good, especially if you plan on actually using QFT a lot and problem solving with it as many calculations are painfully gone through step by step.

But in the end, Weinbergs texts are in my mind is the most complete (and hardest at the lvl of physics rigour) out there (there are harder/more complete versions available for mathematicians and theorists). When you have graduated the first 2 intro classes on QFT, read that text to see what you've been missing =)

When I first took a class in QFT in grad school, we had Zubert's.. Also a nice text, if slightly dated.

 

[aav]

Btw anyone know any good classical field book as well? Cause I'm going to learn both subjects at the same time.

I'm using Goldstein (2nd ed) to review classical field theory. It seems to work for me. The last chapter discusses the Lagrangian and Hamiltonian formulation of fields, the stress-energy tensor, gives several examples of classical fields (relativistic and non-) and ends with Noether's theorem.

 

[marlon]

Zee's book is something you can read start to finish on an airplane or something.

i always hear people saying that. This is a whole lot of crap though.

i challenge everyone to ead this book up side down or whatever and then prove me that they actually understood its content.

No Haelfix, even you studied this very thouroughly for the first time...

These words are just a manifestation of personal over estimation...

It leaves you wanting more at the end,

that is its best quality

a lot of it is just seemingly pulled out of the air,

i disagree, give some examples

and you might be mistaken into thinking QFT is an easy subject.

isn't this a bit ironic ?

marlon

 

[Haelfix]

Well like I said I already knew QFT when I studied Zee's book, so I might be biased.

But I mean look he kinda just throws it at you.. Boom here is the path integral. Here is the Chern Simmons action. This is Noethers theorem. You kinda want to see where some of the motivation is to find these things in the first place. I love his book, I truly do, but it *is* easy reading IMO, at least compared to the other texts out there.

On the complete opposite end of the spectrum is Weinberg. Everyonce and awhile I'll have to look something up , and of course I turn to his book very often (usually in volume3). Except each time I have to remind myself wth all those indices mean and where they came from, and how to get rid of them as soon as possible.

 

[juvenal]

I agree with Marlon that Zee's book is not as easy as Haelfix is making it out to be, especially since the recommendation is for a person starting out in QFT. There are exercises to do in it, after all.

 

[vanesch]

i always hear people saying that. This is a whole lot of crap though.
i challenge everyone to ead this book up side down or whatever and then prove me that they actually understood its content.

Well, I did read it in about 1 1/2 day (and a headache) from cover to cover. I do not claim having understood all of it, but I had the impression, when reading it, that I more or less didn't loose completely the thread of it. This might be mainly an illusion of course, but it didn't stop me reading. In other books, from a certain point on, you have to say that you have now read at least 5 sentences of which you didn't understand a word. That's not true for Zee.

cheers,
patrick.

 

[marlon]

Well like I said I already knew QFT when I studied Zee's book,

so did i. i had already completed my master thesis on quark confinement and the dual abelian higgs model.

But I mean look he kinda just throws it at you.. Boom here is the path integral.

i don't think you read it carefully. he explains this concept along with the mattress model in the very first chapters...he also explains why we use Noether's theorem...

i disagree with the other examples as well, sorry.

regards
marlon

ps we should not even be discussing Weinberg when considereing the very title of this thread

 

[marlon]

Well, I did read it in about 1 1/2 day (and a headache) from cover to cover. I do not claim having understood all of it,

ofcourse you did not.

[/quote]

but I had the impression, when reading it, that I more or less didn't loose completely the thread of it.

i really don't think it is possible/usefull to have an impression of what QFT is about. I mean,, i don't know if you studied it at college but i did and it was the hardest course i ever had to study...it takes several years before you actually can do something useful with QFT, even doing a masters thesis included. So i really have a hard time believing what you say, unless you inveted this theory of QFT to some extent.

In other books, from a certain point on, you have to say that you have now read at least 5 sentences of which you didn't understand a word. That's not true for Zee.

cheers,
patrick.

certainly the truth here. many people (students at colleges) think they know QM or QFT until you start asking questions like :

1) why we use quantum fields ? what is the quantum and the field part about ?
2) what is the canonical formalism ? What does canonical mean ?
3) what is the difference beween dynamical mass generation and the Higgs-related mass generation ?
4) what are dynamical quarks?
5) why do we use duality transforms?
6) what are virtual particles and what conservation laws do they respect/violate
7) what are instantons ?
8) what is asymptotic freedom ?
9) what is the path integral formalism about ?
10) give the biggest conceptual differences between QFT and QM
11) how does the Yang Mills field theories generally work
12) why eight gluons ?
13) how does symmetry account for the existence of gauge bosons ?
14) why no gauge fermions ?

etc etc

answer me to these questions and you know your basic QFT

marlon

 

[vanesch]

i really don't think it is possible/usefull to have an impression of what QFT is about. I mean,, i don't know if you studied it at college but i did and it was the hardest course i ever had to study...

Indeed, I had an (extremely bad) QFT course at university - which was not also very hard but also very confusing, and afterwards I studied Peskin and Schroeder up to a certain point myself (with the help of some internet discussions). Only after that, I read Zee, so it was indeed with some hindsight, but it DID give a view that gave more insight, in certain respects, than the more technical treatments like P&S (where sometimes you're so much burried in the calculational aspects that you loose view on the overall picture).

it takes several years before you actually can do something useful with QFT, even doing a masters thesis included. So i really have a hard time believing what you say, unless you inveted this theory of QFT to some extent.

I am not claiming that after reading Zee, you "know" QFT. But you probably get a better flavor of the subject which can then motivate you more to really delve into the matter in a more technical way.

1) why we use quantum fields ? what is the quantum and the field part about ?

I think I know.

2) what is the canonical formalism ? What does canonical mean ?

I think I know.

3) what is the difference beween dynamical mass generation and the Higgs-related mass generation ?

I think I know

4) what are dynamical quarks?

No idea.

5) why do we use duality transforms?

No idea.

6) what are virtual particles and what conservation laws do they respect/violate

I think I know

7) what are instantons ?

I have some idea.

8) what is asymptotic freedom ?

I think I know.

9) what is the path integral formalism about ?

I think I know

10) give the biggest conceptual differences between QFT and QM

That's a strange question, unless you mean by QM "non-relativistic quantum mechanics".

11) how does the Yang Mills field theories generally work

I think I know

12) why eight gluons ?

I think I know.

13) how does symmetry account for the existence of gauge bosons ?

I think I know.

14) why no gauge fermions ?

I thought I knew, and the discussion here made me see that it is not so evident :-)

From the top of my head, I think many of these questions get a BETTER intuitive answer (true, some technical stuff is hidden) in Zee than in most more calculationally oriented publications.
True, Zee doesn't justify his stuff, and you are probably not up and running to calculate much stuff yourself. But I think nevertheless that it is a great primer.

cheers,
Patrick.

 

[Kruger]

@vanesh: You should know that as scinece advisor :)

 

[marlon]

From the top of my head, I think many of these questions get a BETTER intuitive answer (true, some technical stuff is hidden) in Zee than in most more calculationally oriented publications.
True, Zee doesn't justify his stuff, and you are probably not up and running to calculate much stuff yourself. But I think nevertheless that it is a great primer.

cheers,
Patrick.

Ofcourse this is my whole point. And you know, nobody reads a primer in 1 1/2 days, right ?

marlon

 

[Haelfix]

"i don't think you read it carefully. he explains this concept along with the mattress model in the very first chapters..."

I just opened the book up, and I still think I'm right. He gets the path integral more or less midway from page 10, and derives it for a single particle by the top of page 12. Thats a super fast derivation, I mean come on. By contrast P & S take about 10 pages, only get about half as far as Zee, and only introduce it in chapter 9.

Its perfectly clear in a sense, but it also seems a bit miraculous on first inspection. One is probably still remembering quantum mechanics I, and how that fits in. He also has a rather bizarre substitution table to pass from QM to QFT. I think if I read that book the first time around I would be asking questions like why does that work, why is it unique, is it even consistent etc?

Chern Simmons is done in less than half a page!

 

[baka]

Ugh, A bit loss in the discussion ^^
But bassically everyone agree that Zee is the best place to start with right?

Cheers

 

[dextercioby]

Nope.As i said above,P & S is more oriented towards a textbook.Zee is worthwhile reading,nonetheless.

I've been taught in school following Bailin & Love.If i were to choose between the 2,i'd go for P & S.

Daniel.