I'm setting out to learn all I can about QFT and QED...

I'm setting out to learn all I can about QFT and QED, with the primary goal of one day participating in collision detector data analysis. Can anyone recommend me some shortcuts?

Nobody is gonna accept you to a particle accelerator project if you don't have a degree of mediocrity no matter your knowledge on the subject

>degree of mediocrity
What?

All degrees from all universities jusy prove that you are mediocre, you have the ability to do what you are told to do and you can solve problems which already have a solution. I know, I have one myself

>I know, I have one myself
So do I, but it's in math, not physics. Thats why I want to study this stuff on my own.

Be careful not to cut yourself on that edge.

>All degrees are mediocre
>I know because I have one
>All
>one

Nice induction there bubs

What I'm looking for is simple advice such as "don't waste time on a, focus on b", or "make sure you understand x before you start with y". Thanks in advance.

Actually QED is a QFT.

If you want to get into qft grab the books from Steven Weinberg and Peskin & Schroeder. As you come from a mathematical background you might prefer the weinberg books. If you want to know more about the history of modern qfts you might also read 'elementary particle physics' by Otto nachtmann.

Thanks!

Any other good samaritans with physics degrees out there?

I'll just be periodically bumping my thread with relevant images, forgive me...

>collision detector data analysis.
>Can anyone recommend me some shortcuts?
You don't need QFT and QED.
Just read some kinematics.

That's a mighty shortcut.
I see what you mean, but I guess I want to understand the goal of the experiments... still, your perspective is informative, so i thank you.

How important is it to study the historical development of quantum field theories?

One more bump for the people

You don't need to know the mathematical intricacies of the theories themselves, unless you want to be a theorist. I doubt most of the experimental particle physicists in my group know even the basic definitions..

What DO they need to know?

How to use calculations that theorists give. Cross sections, PDFs, luminosity, parton shower, what collider actually measure. Find a book on collider physics, but one without the words "quantum field theory" in the title. If you wanted to get into "colision detector data analysis", do an undergraduate degree in physics or statistics and apply for jobs. You might actually need a doctorate.

This image pleases me, care to explain it?

I did my undergrad in math, with plenty of analysis and statistics. Thanks for the advice!

Classical Electrodynamics by Walter Greiner, D. Allan Bromley, Sven Soff
Field Quantization by Walter Greiner, Joachim Reinhardt
Relativistic Quantum Mechanics. Wave Equations by Walter Greiner
Quantum Chromodynamics by Walter Greiner, Stefan Schramm, Eckart Stein
Gauge Theory of Weak Interactions by Walter Greiner, Berndt Müller.

It's from an MIT course website, supposedly a different depiction of feynman diagrams. Have you heard of Google reverse image search?

Great, thank you!

There are no shortcuts, just an endless amount of studying book:

Griffiths - Introduction to Quantum Mechanics
Griffiths - Introduction to Elementary Particles
Shankar - Principles of Quantum Mechanics
Sakurai - Modern Quantum Mechanics
Sakurai - Advanced Quantum Mechanics
Landau & Lifshitz - Quantum Mechanics: Non-Relativistic Theory
Landau & Lifshitz - Quantum Electrodynamics
Schwinger - Selected Papers on Quantum Electrodynamics
Feynman, Hibbs, & Styer - Quantum Mechanics and Path Integrals: Emended Edition
Schulman - Techniques and Applications of Path Integration
Peskin & Schroeder - An Introduction to Quantum Field Theory
Weinberg - The Quantum Theory of Fields
Folland - Quantum Field Theory: A Tourist Guide for Mathematicians

This is true for anything serious. People don't care that you have a degree, they care about what courses you took, who you worked with, who'll recommend you, and publishable work you've managed. This is also why athletes, community service, and club people do so well in college apps since it shows they're capable of more than just the basics.

I'm pretty sure this isn't true. Quantum field theory is used for tons of things and just about every physicist knows something about it. You need qft to compute and predict even the most basic interactions.

Classical Mechanics: Learn about Lagrangians and Hamiltonians. How to use them and how Hamiltonians generate time evolution. Landau and Lifshitz or Goldstein. Read chapters 1,2,8,9 of Goldstein.

General Relativity: Learn about metrics, 4 vectors, and tensors. Schutz. Read all the chapters until you learn Einstein field equations in chapter 8. For when you get more serious look at Wald to learn some actual differential geometry.

Electromagnetism: You don't need much of this. Flip through Griffiths book as desired.

Statistical Mechanics: Learn how to turn fundamental laws on the small scale into large scale predictions. Look up David Tong's notes. Landau and Lifshitz is also good.

Quantum Mechanics: Blaze through Griffiths. Don't linger on anything in it too long as it soon won't matter, just get the basic idea. Now go through Shankar with more care. Lastly Sakurai or Weinberg.

Particle Physics: Read Griffiths. Just to get familiar with particles and their history.

Quantum Field Theory: Sakurai, Ryder, Zee, Srednicki, Peskin and Schroeder, Kaku, Weinberg, Wald, Tong and other's notes(Google quantum field theory notes :pdf). Check them all to see which ones you can understand. Now read those ones until you can't understand them anymore. Check them again. Repeat.

Fantastic posts, thank you scholars.

>General Relativity:
This is completely irrelevant to what he wants to do.

I recommended it so he could learn what tensors are and why they're useful. He also won't pick up special relativity anywhere else.

Is special relativity required for QED?

QFT is the unification of QM and SR.

Alright then, thanks!

Not absolutely, "Photons and Atoms: Introduction to Quantum Electrodynamics" by Cohen-Tannoudji for example skirts relativity for most of the book.

Xie-xie

>Can anyone recommend me some shortcuts?

[math]\int {\mathcal{D}A\mathcal{D}\psi \mathcal{D}\bar \psi } \exp \left( {i\int {{\operatorname{d} ^4}x\left[ {\bar \psi \left( {i\not D - m} \right)\psi - \frac{1}{2}Tr{F^2}} \right]} } \right)[/math]

There. Thats QED. Done.

What is it?

Want to identify those terms for me champ?

Isn't anything lost?

If you just know math, you're pretty far from being useful for work on detectors (which is more data analysis and engineering than theoretical physics)

Lol, is this posted by "walter greiner"?? This is worthless and just promotion of the one guy this poster probably knows. Go onto physics stack exchange. I can tell you that, for experimentalists, Mandl and Shaw's QFT and Halzen and Martin's Quarks and Leptons are good for the theory base background, and you'll need MANY other books to learn about detectors, collider pheno, and data analysis (you better be an expert in bayesian analysis, python, etc). Don't listen to the posts in this thread--most of them are complete garbage from people pretending to know. You'll need to study at an actual program though, as nobody will care about your math degree (you'll need some type of degree and project in experimental physics, nuclear or high energy).

NO. Stop posting if you don't know what you're talking about. No good physicist would recommend any Weinberg QFT volume to a beginner trying to do experimental physics. You're a fucking idiot, and OP please ignore this douche. He's just listing books he's probably never used that are popular (or just mindlessly took courses on these books and listed them)

Become a cute trap and get really good at suckinf dick. Then maybe I'll let you sweep the floor in the control room at CERN

Just do yourself a big favor and go on stack exchange. It's pretty obvious that the posters in this forum have very little experience with what an experimental physicist who works on colliders needs. You don't need to be able to calculate things from Peskin and Shroeder (at least until you're more advanced). Only try for basic QFT books to get your feet wet. Advanced EM is more useful (wave propagation in matter). But BY FAR the most useful are data analysis techniques. I do high energy theory, and most of my experimental colleagues spend the VAST majority of their time doing data analysis--know how to write and run a monte carlo simulation. Know the necessary relativistic kinematics and what the phase space tells you about the signature of the fundamental interactions. Take a glance at the summary sections of PDG (particle data grouop) and look at their references--this is the actual stuff you'll need in practice. Things that sound fancy are going to be out of your league for a while and not worth the time. Focus on being useful. And please, check out physics stackexchange if you're legit interested. Veeky Forums is mostly wanna-be intellectuals and undergrads.

>discouragement
Why? If it were true that I only knew math, then this might actually be effective, but it's certainly not helpful regardless

Roughly, the fields:

psi electron
psibar positron
A photon


The term [math]{\bar \psi \left( {i\not D - m} \right)\psi }[/math] is a Dirac term describing the dynamics of the spinor fields. The Dirac operator [math]\not D = {\gamma ^\mu }\left( {{\partial _\mu } - ie{A_\mu }} \right)[/math] couples the spinor fields to the gauge field.

The second term is, [math] Tr{F^2} = \frac{1}{2}\left( {{\partial _\mu }{A_\nu } - {\partial _\nu }{A_\mu }} \right)\left( {{\partial ^\mu }{A^\nu } - {\partial ^\nu }{A^\mu }} \right)[/math], it is the "Maxwell term" in the sense that its classical equations of motion are Maxwell's equations.


The inner integral is just giving up the action from the lagrangian density.
The outer integral is the Feynman integral corresponding to "quantization."

i.e. To calculate an amplitude you roughly take, [math] \left\langle 0 \right|\psi \left( {{x_1}} \right)A\left( {{x_2}} \right)\left| 0 \right\rangle = \int {\mathcal{D}A\mathcal{D}\psi \mathcal{D}\bar \psi } \exp \left( {i\int {{\operatorname{d} ^4}x\left[ {\bar \psi \left( {i\not D - m} \right)\psi - \frac{1}{2}Tr{F^2}} \right]} } \right)\psi \left( {{x_1}} \right)A\left( {{x_2}} \right)[/math]

>you'll need some type of degree in physics
You may be right, sadly. Thanks for your advice. In any case, I want to learn on my own first.

Sorry, I posted both the post you responded to here and many of the next few that were trying to point you in the right direction. This was just a lead in, where I want you to understand what people who work in collider physics actually do (to make sure that's what you really want) and to also explain the somewhat long-road ahead. You'll very likely have to pursue a physics phd program to accomplish this, so although I gave a lot of feedback for what being a collider physicist entails, the practical approach to your question is probably to make sure that you can get into physics grad school (good gpa (3.6+ min), good physics gre (~750 min) and rec letters from whoever. The rest will come (or you can follow some of the advice set out and pursue more at more reputable sites)

Beautiful post, thank you.

Fantastic, thank you. GPA is no problem, GRE I have yet to take. Still, I'm mostly concerned about finances when it comes to grad school.

Thanks, very helpful (I think!)

Are you international? If you're domestic you needn't worry--if you have a good GPA/test scores/ rec letters / some research experience, any decent grad school will pay your tuition and give you a ~$20-30k stipend for the first year or so. After that, you'll be paid a similar amount either by your advisor (if you're lucky and he has funding) or to TA classes (the university will pay this). If you're international, you'll just have to TA immediately; but either way--living expenses and such are covered by american university phd programs. (I assume of course you're talking about USA phd programs. Unfortunately, I know very little about the inner workings of international schools, as my only experience outside the usa is one singular postdoc appt)

I sure hope you're right. I need to nail the GRE for sure...

Even experimentalists should ideally work through at least some of Perkin Schroeder.
But I agree, stack exchange is the canonical choice for advice.

>Don't linger on anything in [Griffiths] too long as it soon won't matter

why's that?

OP ask to learn ALL he could about QFT. Eventually you will read Weinberg.

>This data monkey thinks he's a physicists

How cute.

Griffiths is just to get some intuition behind quantum mechanics. Anything serious will be treated better in Shankar.

As mentioned in my comments, I'm a theoretical high energy physicist. I'm just being honest about what being an experimental HEP physicist is (where the biggest challenge is working through HUGE data sets as particle accelerators basically collide a milky way's worth of stars (particles, 10^11) together every few nanoseconds. If you don't get this, you're pretty naive and unhelpful.

I haven't met very many experimentalist faculty who have read Weinberg. So you're completely wrong. Maybe at a few unis, but it's definitely not the norm. So don't be naive. You just sound like an intro grad student with un-tested ideas of what "should" happen and very little actual experience.

Also, I'm not sure I can name a single faculty member that does not work with computations in some large capacity. Whether it's phase space simulations for model phenomenology or calculating the ungodly number of diagrams at three-loop level, computers and data analysis now come with the field. If you'd rather disparage this and pretend it's not the case, you're either living 30 years in the past or have no idea how modern HEP actually functions. Typical /sci poster though, I suppose. You let me know if you feel the same way after you have your phd kid.

>he isn't a mathematical physicist

Very few people are, and generally, theorist does not mean "mathematical physicist." I myself only use computers to crunch pheno model predictions (madgraph, etc), so it has very little to do with the theory I do. I'm just saying you're completely naive about the nature of almost the entire field outside of a very small subset, so you should be a little more cautious about butting in.

Go ahead and read the arxiv in hep theory, pheno, and experimental and tell me what percentage of papers involve no computational work. The fucking undergrads/ into phd students always running their mouth on /sci. Jesus.

Not the user you seem to think I am, but chances are I know more physics (not to mention mathematics) and am at a better university than any you have studied at.

I do appreciate all of HEP but I think you are mauve if you think the future of physics is not determined by the mathematical physicists who actually talk to pure mathematicians as well as physicists.
All theory involves computation, some don't necessarily need or can currently computers to do that work for them.

>naïve
>or can currently use
Sorry on phone

I highly doubt it as I got both my undergrad and phd from top 20 programs (with worthless ranking), but with a very influential phd advisor and 1st postdoc advisor. The fact you think "better university" matters at an advances stage shows how naive you are--that shit doesn't matter--only your graduate advisor's influence, the quality of your papers, and your ability to collab and network matter. What have you done that's so great? Or are you still in grad school and just think you're hot shit? How many papers currently? What's your h index?

And by "worthless ranking" I mean that ranking hardly matters after undergrad (minus first year courses if you have to suffer through those). BUt please, tell me your field, what you specialize in, and the above that I asked for if you're so godly. Because I haven't seen you convey a lick of physics knowledge yet.

To inform you, I study the thermal history of the universe, build various unification mechanisms, work on the particle origin of dark matter, and the origin of neutrino mass. Please show me how you're better and more knowledgeable at physics than I am, and how you're more equipped to talk about high energy collider physics (the topic of this thread) than I am.

If I told you the university or my advisor (If you work in theory you would know him by name) you could figure out who I was. Yes Phd, but according to the aforementioned advisor one of the best he has had.

I didn't ask for your university or advisor. I'm asking you for what you work on, how many publications you have, etc. But if you're still a grad student, I guarantee you don't know more than me. As I've already mentioned, I've finished my phd and have had multiple postdocs leading me to my current appointment. You shouldn't be so cocky as a graduate student as you probably haven't done much work outside of your advisor's main focuses. That means you have very little understanding of the field in general. And if you don't even have 10 papers? Pretty ballsy to assume that you "know more." Why do you think so? Because you know qft very well? Guess what? So does every single HEP theorist who isn't worthless. Also, "one of the best he's had?" So is everybody who stays in the field past phd. That's why when you apply to postdocs they basically overlook your advisor's rec letter and see what collabs you've done. I hope your advisor gives a better sense of how the field works before you apply to post-doc or you'll be in for a very rude awakening.

First time on Veeky Forums a reply has actually induced a sense of anxiety in me, I admit. Alright user I shall heed your advice.

I could end up working in a math department anyway.

Since the advice I've received in this thread has only become increasingly critical and informative, I'll give it another bump.