Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A Infinite-dimensional symmetry...

  1. Nov 16, 2018 #1
    In a recent paper in Physical Review Letters, Prof. Krzysztof Meissner from the Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, and Prof. Hermann Nicolai from the Max-Planck-Institut für Gravitationsphysik in Potsdam have presented a new scheme generalizing the Standard Model that incorporates gravitation into the description. The new model applies a kind of symmetry not previously used in the description of elementary particles.
    Could some-one who understands this math please translate ??
    The bits I recognised look very hopeful, there are robust 'this would falsify it' suggestions, but the rest is beyond me...
  2. jcsd
  3. Nov 21, 2018 #2
    Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.
  4. Dec 7, 2018 #3
    The paper seems very interesting to me as well, but, like you, I am not an expert in this field and so can't really comment on the specifics. I would have thought there would be more excitement from the expert community, though, as it seems *to me* (as a non-expert) that this is finally a Theory of Everything that actually does, finally, combine the Standard Model with all the correct particles and their observed charges with General Relativity. Even better, it's supposed to be falsifiable. That seems a pretty big deal to me! Or am I perhaps missing something fatal flaw in this proposal?

    I do have some specific questions for the experts, besides just if they generally believe the proposal to be viable or not:

    1. What I'm not really clear on is if this model is UV complete. If it is, how does it avoid the usual difficulties of Landau poles, non-renormalizability of gravity, etc. Is there some kind of asymptotic safety mechanism at work there? Or is the theory still not UV complete, and hence just an effective quantum field theory, even though it includes more-or-less all the physics ever observed (aside from dark matter and dark energy?)?
    2. Is there a candidate for dark matter in the proposal? What about the issue of dark energy?
    3. Which specific lowest-energy particle not yet observed could serve to prove or disprove the proposal?
    4. The conclusion mentions the prediction for new sterile fermions. Does this include sterile neutrinos supposedly observed recently by the MiniBooNE experiment at Fermilab (https://physicsworld.com/a/evidence-for-sterile-neutrinos-claimed-by-fermilab-experiment/)?

    Hopefully someone can provide a little more clarity on the matter. :)
  5. Dec 7, 2018 #4
    This is the paper.

    The infinite-dimensional symmetry is E10, two steps beyond the famous E8, which is 248-dimensional. Coauthor Nicolai has a proposal that E10 is the symmetry behind M-theory.

    The prehistory of this paper goes back to just before string theory, when N=8 supergravity (a field theory) was tantalizing theorists. People noticed that it has the same number of spin 1/2 fermions as the standard model, and would love to break the SU(8) symmetry of the theory to the standard model gauge group, but couldn't quite do it.

    Meissner and Nicolai seem to say there's an SU(56) subgroup of E10, elements of which can implement the standard model symmetry transformations on the fermions. So the big picture is apparently that they want to get M-theory from E10, and you can get N=8 supergravity from M-theory, so they are hoping that their E10-based M-theory can finally implement this old dream of an "N=8 standard model".

    But for now their E10-based M-theory doesn't exist. Usually gauge symmetries are separate from spacetime symmetries, but E10 is to include both and they don't know how it should work. In other words: they have implemented part of the "N=8 standard model" by embedding the standard model symmetry in SU(56), but because of how E10 is supposed to work in their scheme, they can't finish the job by just gauging SU(56) as in a usual field theory.

    The predictions of extra particles come about, because the d=4 N=8 supermultiplet also contains eight gravitinos, and apparently the SU(56) construction implies that they should have standard model charges. It sounds odd to me, and a bad property for dark matter to have, and that part of the paper is just handwaving, there's no calculation.

    So it's all moderately interesting but there's no guarantee that it works even as mathematics. They have an idea for how to assemble a jigsaw but they don't actually know that any combination of the necessary pieces, actually fits together in the way that they intend.
  6. Dec 8, 2018 #5


    User Avatar
    Science Advisor

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?