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Neutrino miminal standard model vs string/M-theory

  1. Dec 8, 2015 #1
    back ground

    Asymptotic safety of gravity and the Higgs boson mass
    Mikhail Shaposhnikov, Christof Wetterich
    (Submitted on 1 Dec 2009 (v1), last revised 12 Jan 2010 (this version, v2))
    There are indications that gravity is asymptotically safe. The Standard Model (SM) plus gravity could be valid up to arbitrarily high energies. Supposing that this is indeed the case and assuming that there are no intermediate energy scales between the Fermi and Planck scales we address the question of whether the mass of the Higgs boson mH can be predicted. For a positive gravity induced anomalous dimension Aλ>0 the running of the quartic scalar self interaction λ at scales beyond the Planck mass is determined by a fixed point at zero. This results in mH=mmin=126 GeV, with only a few GeV uncertainty. This prediction is independent of the details of the short distance running and holds for a wide class of extensions of the SM as well. For Aλ<0 one finds mH in the interval mmin<mH<mmax≃174 GeV, now sensitive to Aλ and other properties of the short distance running. The case Aλ>0 is favored by explicit computations existing in the literature.
    8 pages
    155 citations

    in this paper and in others, Asymptotic safety of gravity and the Higgs boson mass they calculate the Higgs boson to be 126 GEV in 2009 about 5 years before its discovery. a concrete and falsifiable prediction.

    in their proposal of the
    Neutrino Minimal Standard Model

    if true, how would this impact string/M theory research and super gravity?

    the authors argue there is no supersymmetry, no grand unification, no extra dimensions, dimensions set at 4, no new physics from fermi scale to planck scale, dark matter is sterile neutrinos, not neutralinos of SUSY,
    Neutrino Minimal Standard Model with Asymptotic safety of gravity is final theory.

    they also claim vaccuum stability as another prediction.

    how would the widespread acceptance of this theory impact string/m theory research?
  2. jcsd
  3. Dec 8, 2015 #2


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    There is a "folk theorem" that supersymmetry is the low energy effective field of every possible string theory that could be real. I do not know if this has any rigorous basis, and if so, what assumptions go into it. But, many people in the field, especially string theorists, believe it to be true or highly likely to be true, whether or not it has been proven.

    The fact that this paper hit the nail on the head in terms of predictions is less impressive when you recall how many predictions were outstanding at all sorts of Higgs masses with all sorts of uncertainties, including contrary predictions by the authors of that paper at very different values. Quite a few completely different theories lucked out and got the right answer by completely different means.

    I think that the widespread acceptance of this theory by people who do string/m theory research is a event with a probability approaching zero.
  4. Dec 8, 2015 #3
    i'm question isn't whether Ed Witten or Eva Silverstein will accept vMSM but the physics community in general. Is string-M theory compatible with vMSM?
  5. Dec 10, 2015 #4
    You could certainly look for the vMSM in the string landscape. For example, a vacuum with SO(10) grand unification and N=1 supersymmetry, where both symmetries are broken at the Planck scale. But the special values of Higgs and top at Planck scale would have to come from something other than asymptotic safety (e.g. yet another symmetry), since string theory doesn't have that property.
  6. Dec 10, 2015 #5


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    The string theory community is such a large percentage of the physics community in general right now, that it is at least a generation or so before anything that is not accepted by the string theory community could be accepted by "the physics community in general." In many of the critical subfields string theorists have majorities of physicists practicing.
  7. Dec 10, 2015 #6


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    That statement surprised me, OhW. Do you have some statistics covering the physics community in general?
    That would include experimentalists, people in condensed matter, astrophysics including astroparticle physics, various branches of phenomenology...
    Aren't there people specializing in extensions of the Standard Model using ordinary Quantum Field Theory? Are they outnumbered by those still actively trying to base the SM on superstring/m?
    Last edited: Dec 10, 2015
  8. Dec 10, 2015 #7


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    My assumption is that only particle physicist (experimentalists, phenomenologists, lattice, and theoretical) folks would be in the relevant pool of people in general having an opinion, with condensed matter and astrophysics people, e.g., pretty much agnostic. I've seen statements about faculties at various university programs being majority or even completely or completely minus one stringy, and the influence of stringy folks at the LHC while perhaps not as deep seems just as wide. My impression is that the non-stringy people are outnumbered collectively among people who are doing something that is an alternative to string theory as opposed to something entirely different (e.g. Navier-Stokes law analysis or complex systems or descriptive astronomy). I've seen one or two larger surveys, not really up to scientific survey standards, a few years ago. I've also heard complaints about dominance in grants, prestige jobs, etc. of the string tribe, but don't have references easily at hand. The Perimeter Institute has made a dent, but that is one prominent island among a lot of less well known ones.

    FWIW, regardless of percentages, there is definitely enough of a critical mass of string theorists that I don't think any non-stringy idea could be a consensus one until the old guard of them dies off.
  9. Dec 10, 2015 #8
    I understand how they can be reluctant to let go of their main occupation over a long time.
    I only hope they are open enough to judge any alternatives based on its merits even if it means they spent a lot of time chasing nothing to state it harshly.

    Ideally we would have a decent amount of physicists that are equally well versed in 2 possible candidates for a theory of QG.
    That way they can both act as a moderator in debates but also (semi)objectively compare the approaches.
    However this is virtually impossible as I see it. You need to publish often enough to secure funding.
  10. Dec 10, 2015 #9
    what prevents gravity from asymptotic safe in string theory?
  11. Dec 13, 2015 #10
    The philosophy of asymptotic safety is that the path integral includes field modes of arbitrarily high frequency, creating ultraviolet divergences, but that these can be renormalized away. The philosophy of string theory is that the path integral is a sum over string histories which, unlike field theory amplitudes, do not diverge in the ultraviolet. So they seem to be incompatible.
  12. Dec 14, 2015 #11
    how successful is asymptotic safety?
  13. Dec 17, 2015 #12
    That depends who you ask. The classic view in particle physics is that if you quantize general relativity, you get a theory with infinitely many coupling constants, and that quantum gravity can't be a field theory anyway, because of black hole thermodynamics and "no local observables", hence string theory. Meanwhile, the asymptotic safety people see themselves as collecting evidence that quantized general relativity will have only a finite number of coupling constants after all, but their critics don't trust their methods or understand certain claims that are made.

    However, none of that plays a role in the paper of Shaposhnikov and Wetterich. Their real observation is just that, assuming a UV fixed point for quantum gravity, and a few other things, then the quartic self-coupling of the Higgs, and the beta function of that coupling, both go to zero at high energies; and that in turn implies the predicted mass. It's that intermediate step (specific quantities go to zero) that one would try to reproduce in a stringy vMSM.
  14. Dec 17, 2015 #13
    are these physically reasonable assumptions ?
    Last edited: Dec 17, 2015
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