Whatever happened to Thirring and Nambu-Jona-Lasinio

OOO

I have noticed that in the nineties there was a boost of activity on the Thirring and Nambu-Jona-Lasinio models and bosonization, which I find highly interesting. I have already got me a huge (virtual) pile of papers to wade through.

But probably it will save me a lot of wasted time if somebody here could answer the following questions:

* What stopped interest in these models ?
* Are they too simple ?
* Have they got serious flaws ?
* Is bosonization related to supersymmetry ?

blechman

people are still working on it, but what is it you want to do? These models basically showed us how to spontaneously break a gauge symmetry by a fermion condensate, in direct analogy with BCS superconductors. OK, now what? We already have (and ruled out) technicolor. Also, as you mention, they're kind of silly models: D=2, large N.... They were (and are) very important to justify things, but what do you plan to do with them now that they've been worked out?

OOO

I have just noticed the equivalence between Thirring and Sine-Gordon and thought it is interesting that bosons and fermions are in a sense equivalent. Especially if one thinks of the difficulties with fermions in several applications...

I've already learnt about the special role of the conformal group being infinite dimensional in D=2 but not in D>2. But I can hardly believe that this only works in 2D. Perhaps there are some yet undiscovered connections between fermions and bosons. Hence my question about the connection to SUSY, though I don't know if this is at all in the same league.

But I'm a novice and probably this is all pointless.

blechman

Nothing pointless in a good question! ;-)

A famous example of this kind of thing (susy + fermion condensation) is "gaugino condensation". Look that one up. There are others as well.

Play with it, have fun! Historically, I think that NJL was important in high-energy theory to motivate technicolor, and after that, people were satisfied (it's in that context that I learned it). I'm not an expert in NJL research of the 1990's though, so maybe it's found another home.

OOO

Sane attitude. Although one tries not to reinvent the wheel... It's not easy to do something new, let alone finding something important.

Thanks a lot, blechman.

arivero

Empirical proof attached: myself, a bored day about 2005 or 2006. Yes, 2006 CE, no 2006 BCE. Note: Hereby I put the last picture in the public domain, license free, just in case you want to use it as example somewhere.

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mormonator_rm

LOL... at least you chose something safe to reinvent, arivero. One of my best friends in highschool and I, back in 1999, decided to "reinvent" the shoulder-fired rocket launcher (with model rocket engines, parts, and equipment from "Estes"), with especially dreadful results; we stood together in a creek basin behind the woods near my house, and both of us wore goggles and hard hats. My friend stood behind a tree, and I fired the thing up the hill. It did exactly as we were hoping for it to do... until it bounced off of a rock. It came shrieking back down the hill at us, rolling end-over-end, and landed in the creek right at my feet. We watched it finish burning out underwater. We went home a bit freaked out after that. If I had taken pictures I would post them, but I never took any pictures...

On a more relevant note, I think it is often a good idea to "reinvent" some things for yourself, just so you can become familiar with them. Alot of my experience in particle physics has been all about "reinventing" different aspects of the standard model that I've been interested in. I gained a better understanding that way than I ever got from my undergrad classes. Its interesting; some of my earliest, and most embarrasingly naive, work in physics research, when I was in the "reinventing" phase, led directly to some of my latest and most notable journeys in physics theory.

arivero

Bah, as they say, that is not rocket science. Oh, wait, it is.

blechman

tell me about it!!

I also agree whole-heartedly with mormonator_rm. I've done a whole lot of "reinventing" - you'll never learn anything if you just read it and take the word of fools like me! ;-)

OOO

mormonator_rm, arivero, blechman,

thanks again for all your encouraging and entertaining words. So I guess the first thing for me to do will be trying to forget that I may be hit by my own rocket...

mormonator_rm

Just a word of advice...

If you are going to "reinvent" something, choose the item wisely.

As I discovered, weapons are not safe to "reinvent"...

Physics theories, however, are certainly safe to "reinvent", as long as you can get good information from the right sources. In the beginning you just need to focus on having fun, and don't take it too seriously. You will follow in the footsteps of many who have gone before you, and you will find a sense of accomplishment in figuring out how they did it, and seeing your results match theirs. As you go further along, you will find yourself "reinventing" things which may not have been invented yet, at which point you are no longer "reinventing". Just enjoy what you are doing, finish your education, and in time you will happily go down your chosen path.

blechman

well said!