marcus said:
Hi PAllen,
Its possible some of the "other forum threads" relating to minimalist proposals were ones I started. Are you familiar with what could be called "no-frills" proposals of the following two sets of authors?
Hermann Nicolai and Kris Meissner
Shaposhnikov and friends
I've seen a couple of threads of yours here, not sure I've seen these specifically. I was using the work 'minimal' in a generic sense, interesting that it might have a more specific sense similar to what I was getting at.
marcus said:
Nicolai presented his idea at the July 2009 XXV Max Born conference. It was LHC testable, predicted no new energy scales between EW and the Planck scale, required just one new field. No low energy SUSY. No extra dimensions etc. Gravity was not included in the talk, as I recall, but they have described a way to include it elsewhere. The slides are here:
http://www.ift.uni.wroc.pl/~planckscale/lectures/1-Monday/3-Nicolai.pdf
The 40 minute video of Nicolai's talk is here:
http://www.ift.uni.wroc.pl/~planckscale/movie/
The first 5 minutes provides an "executive summary" so you can get the gist without going the whole 40 minutes.
He referred to Shaposhnikov's work, and Shaposhnikov has also cited the Nicolai Meissner papers. Some points of similarity.
That's really interesting, especially if they tackle gravity. Do they have dark matter candidate and any approach for dark energy? (I will look over these references, but can't right away; by look at, I mean understand what I can from the abstract and general logic; I can't follow details of such papers). I am particularly interested in the idea of explaining the major evidence beyond SM with a theory that may not be 'ultimate' but is less of a leap than M-theory. In effect, suppose something like M-theory is the ultimate theory at the Planck scale, yet given the enormous difficulties of completing its formulation let alone understanding how to use it, it could be really worthwhile to pursue more partial theories that make progress on currently known conundrums.
Besides dark matter, and dark energy, other things that might progress are reducing the number of free parameters in SM via some new explanations. I remember in high school (60s) raising the plethora of particle masses as a signficant thing to explain, and being told that 'well, no one knows how to use such information'. Then, over next 10 years we get SM that now does derive things like proton/neutron mass (and was theoretically expected to explain such things evern before the calculations could be carried out).
Of course, I know the landscape hypothesis suggests most of these parameters may be accidents, and I can't say 'I know this is wrong', but I hope it is. I remember clearly the initial excitement with string theory, including the expectation (more than just a hope) that virtually all of these parameters would be derived quantities in string theory.
I've become somewhat enthusiastic about SUSY without string theory as a practical approach because of the synergy between something originating with unification (GUTs, QG separate from string theory as well as within string theory) that also predicts the seeming best candidate for dark matter so far. The big difficulty here (my opinion) being how to pick some preferred SUSY extension and work out the details.
marcus said:
I've reported on these minimalist initiatives in other threads. So I am curious if these are some of what you were thinking. I haven't paid much attention to Effective Field Theory (EFT) à la John F Donoghue and several others, because I've been interested especially in Nicolai Meissner ideas. There is something more to it---the attempt is to extend the Standard Model, with very little extra, all the way to Planck scale and get something moreover that the LHC could falsify.
Their first paper was written in 2006 and has been followed up by a handful of others, indeed they just posted a new one in October 2010.
Here's the 2006 paper:
http://arXiv.org/abs/hep-th/0612165
A good way to dig up minimalist papers might be to look down the list of the 40 papers that cited it:
http://www.slac.stanford.edu/spires/find/hep?c=PHLTA,B648,312
I've highlighted some bits of your post that interested me especially.
Atyy has posted several papers on effective field theory approach to quantum gravity over on the relativity forum. From these I perceive recent progress. Yes, one of them was by John F. Donoghue. What I like here is the ability to actually do quantum gravity calculations right now. Unfortunately, they seem to suggest that deviations from GR may not be testable for a long time.
A separate line of thought is the 'is quantum gravity' necessary at all. I am thinking here about recent papers arguing that you can 'almost prove' that the graviton will never be detected, even if it exists. Given the key role of the photon's particle like properties in the development of QM, this makes me ask the question of necessity for the whole enterprise. For example:
http://arxiv.org/abs/gr-qc/0601043
Closely related are papers like the following, proposing that the need for unification itself should be subject to experiment and is not strictly required:
http://arxiv.org/abs/0803.3456
http://arxiv.org/abs/0802.1978
http://arxiv.org/abs/0809.4218
Hope this reply isn't too 'all over the place'. My main thrust is there is a lot that can be done while 'waiting for TOE', if we need it at all. However, I don't perceive any 'problem' in theoretical physics. I have seen your (Marcus) threads noting changes in emphasis in research, and that is the natural way such things sort themselves out.
