Comments on: Muon g-2 and Supersymmetry http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/ private thoughts of a physicist and chessplayer Thu, 24 Dec 2009 08:50:26 +0000 http://wordpress.com/ hourly 1 By: 3.3 sigma or 2 sigma for g-2 ? « A Quantum Diaries Survivor http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11472 3.3 sigma or 2 sigma for g-2 ? « A Quantum Diaries Survivor Thu, 28 Sep 2006 22:06:28 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11472 [...] During her introduction to the discussion, she presented the discrepancy between experimental determination of muon g-2 and theoretical predictions as a 3.3 sigma effect. I was puzzled, since I had just read a review paper issued this very month on Hep-Ph which quoted a 2-sigma effect (see my former post in http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/). [...] [...] During her introduction to the discussion, she presented the discrepancy between experimental determination of muon g-2 and theoretical predictions as a 3.3 sigma effect. I was puzzled, since I had just read a review paper issued this very month on Hep-Ph which quoted a 2-sigma effect (see my former post in http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/). [...]

]]> By: Chris Oakley http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11385 Chris Oakley Sat, 23 Sep 2006 22:53:51 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11385 OK - but one hears the claim of "best theory ever" as describing QED so regularly that someone needs to sound a cautionary note. The <i>g</i>-2 prediction is supposedly one of the jewels in the crown of the theory, but if, after choosing a different renormalization method, I got a different answer then I would be regarded as a spoilsport rather than exercising legitimate scientific scepticism. <i>That</i> is the power of the group mentality. OK – but one hears the claim of “best theory ever” as describing QED so regularly that someone needs to sound a cautionary note. The g-2 prediction is supposedly one of the jewels in the crown of the theory, but if, after choosing a different renormalization method, I got a different answer then I would be regarded as a spoilsport rather than exercising legitimate scientific scepticism. That is the power of the group mentality.

]]> By: dorigo http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11377 dorigo Sat, 23 Sep 2006 18:08:43 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11377 Hi Chris, what you write above sort of scares me... I need to think about that (provided I can still think!) Cheers, T. Hi Chris,

what you write above sort of scares me… I need to think about that (provided I can still think!)

Cheers,
T.

]]> By: Chris Oakley http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11356 Chris Oakley Fri, 22 Sep 2006 08:15:21 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11356 Renormalization is the main raison d'etre for many HEP theory groups. The tree diagrams experimentalists can calculate for themselves. It is for loop calculations, such as the one that leads to g-2 that you defer to the theorists. You let them practise their voodoo without seriously asking whether it rests on substantial mathematical foundations. It does not, and if anyone questions this they can be silenced with the greatest of ease, as I discovered, by not admitting them to the club. But the club is actually more like a priesthood ... you are only allowed to be sceptical up to a point. It is mostly about demonstrating how well you can synchronise your brainwaves with the collective mind. To be more concrete about this, supposing that the NR Schroedinger equation resulted in all the energy levels of the Hydrogen atom being infinite, but then, by subtraction of infinite "counterterms" you could get the familiar -R∞/(n^2) energy levels. Would you accept that? I think not. Why should it be different in the second quantized world? Renormalization is the main raison d’etre for many HEP theory groups. The tree diagrams experimentalists can calculate for themselves. It is for loop calculations, such as the one that leads to g-2 that you defer to the theorists. You let them practise their voodoo without seriously asking whether it rests on substantial mathematical foundations. It does not, and if anyone questions this they can be silenced with the greatest of ease, as I discovered, by not admitting them to the club. But the club is actually more like a priesthood … you are only allowed to be sceptical up to a point. It is mostly about demonstrating how well you can synchronise your brainwaves with the collective mind.

To be more concrete about this, supposing that the NR Schroedinger equation resulted in all the energy levels of the Hydrogen atom being infinite, but then, by subtraction of infinite “counterterms” you could get the familiar -R∞/(n^2) energy levels. Would you accept that? I think not. Why should it be different in the second quantized world?

]]> By: dorigo http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11347 dorigo Thu, 21 Sep 2006 21:23:28 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11347 Hi Chris, hmmm, yes, I understand your point. However, I would still be waiting for an explanation - I am not too picky, and I can be easily tricked. Ignorance is bliss, as they say... Cheers, T. Hi Chris,

hmmm, yes, I understand your point. However, I would still be waiting for an explanation – I am not too picky, and I can be easily tricked. Ignorance is bliss, as they say…

Cheers,
T.

]]> By: Chris Oakley http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11346 Chris Oakley Thu, 21 Sep 2006 21:12:59 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11346 In that case you don't expect much. The "standard model" predictions of which you speak can be related to quantum field theory in some sense up to tree level, but once loops start to appear the renormalization scheme is everything and the fact that consensus has emerged about how the renormalization is should be done does not make it mathematically respectable. I could, for example, choose a scheme whereby I get perfect agreement with experiment for g-2, but all I am doing is choosing ∞-∞ to be the number I want to get. In that case you don’t expect much. The “standard model” predictions of which you speak can be related to quantum field theory in some sense up to tree level, but once loops start to appear the renormalization scheme is everything and the fact that consensus has emerged about how the renormalization is should be done does not make it mathematically respectable. I could, for example, choose a scheme whereby I get perfect agreement with experiment for g-2, but all I am doing is choosing ∞-∞ to be the number I want to get.

]]> By: dorigo http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11344 dorigo Thu, 21 Sep 2006 20:40:48 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11344 Lol... I hope that I live to see g-2 diverge enough from SM predictions that we'll all start jumping on our chairs waiting for theoreticians to come up with a handwaving argument for its observed value :) Cheers, T. Lol…

I hope that I live to see g-2 diverge enough from SM predictions that we’ll all start jumping on our chairs waiting for theoreticians to come up with a handwaving argument for its observed value :)

Cheers,
T.

]]> By: Chris Oakley http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11343 Chris Oakley Thu, 21 Sep 2006 20:04:19 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11343 I hope that I live to see a theoretical prediction of g-2 not based on handwaving arguments. I hope that I live to see a theoretical prediction of g-2 not based on handwaving arguments.

]]> By: dorigo http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11334 dorigo Wed, 20 Sep 2006 19:01:43 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11334 Yes, indeed. Good point. In fact, almost any new physics has in principle the potential to modify the muon gyromagnetic ratio, just as much as it would be likely to destroy the perfect agreement of the unitarity triangle determinations from very different physics measurements. T. Yes, indeed. Good point.

In fact, almost any new physics has in principle the potential to modify the muon gyromagnetic ratio, just as much as it would be likely to destroy the perfect agreement of the unitarity triangle determinations from very different physics measurements.

T.

]]> By: Guess Who http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11332 Guess Who Wed, 20 Sep 2006 17:51:28 +0000 http://dorigo.wordpress.com/2006/09/20/muon-g-2-and-supersymmetry/#comment-11332 ...or it could be the first experimental sign of preons: http://arxiv.org/abs/hep-ph/0103317 …or it could be the first experimental sign of preons:

http://arxiv.org/abs/hep-ph/0103317

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