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Would NMSM or vMSM + 4D QG like LQG or AsG be TOE?

  1. Dec 30, 2015 #1
    thus far the LHC has not seen any SUSY in run 2, with possible exception of the 750 scarlar boson which may disappear with further data.

    If LHC run 2 provides no BSM type physics, would either

    The New Minimal Standard Model
    Hooman Davoudiasl, Ryuichiro Kitano, Tianjun Li, Hitoshi Murayama
    (Submitted on 12 May 2004 (v1), last revised 13 Jan 2005 (this version, v2))
    We construct the New Minimal Standard Model that incorporates the new discoveries of physics beyond the Minimal Standard Model (MSM): Dark Energy, non-baryonic Dark Matter, neutrino masses, as well as baryon asymmetry and cosmic inflation, adopting the principle of minimal particle content and the most general renormalizable Lagrangian. We base the model purely on empirical facts rather than aesthetics. We need only six new degrees of freedom beyond the MSM. It is free from excessive flavor-changing effects, CP violation, too-rapid proton decay, problems with electroweak precision data, and unwanted cosmological relics. Any model of physics beyond the MSM should be measured against the phenomenological success of this model.
    Comments: 5 pages, 2 figures. The discussions expanded with clarifications. The version accepted for publication in Phys. Lett. B
    Subjects: High Energy Physics - Phenomenology (hep-ph); Astrophysics (astro-ph); High Energy Physics - Theory (hep-th)
    Journal reference: Phys.Lett.B609:117-123,2005
    DOI: http://arxiv.org/ct?url=http%3A%2F%2Fdx.doi.org%2F10%252E1016%2Fj%252Ephysletb%252E2005%252E01%252E026&v=f0839b57 [Broken]
    Cite as: arXiv:hep-ph/0405097

    or

    The nuMSM, leptonic asymmetries, and properties of singlet fermions
    Mikhail Shaposhnikov
    (Submitted on 29 Apr 2008 (v1), last revised 5 Aug 2008 (this version, v2))
    We study in detail the mechanism of baryon and lepton asymmetry generation in the framework of the νMSM (an extension of the Standard Model by three singlet fermions with masses smaller than the electroweak scale). We elucidate the issue of CP-violation in the model and define the phase relevant for baryogenesis. We clarify the question of quantum-mechanical coherence, essential for the lepton asymmetry generation in singlet fermion oscillations and compute the relevant damping rates. The range of masses and couplings of singlet leptons which can lead to successful baryogenesis is determined. The conditions which ensure survival of primordial (existing above the electroweak temperatures) asymmetries in different leptonic numbers are analysed. We address the question whether CP-violating reactions with lepton number non-conservation can produce leptonic asymmetry {\em below} the sphaleron freeze-out temperature. This asymmetry, if created, leads to resonant production of dark matter sterile neutrinos. We show that the requirement that a significant lepton asymmetry be produced puts stringent constraints on the properties of a pair of nearly degenerate singlet fermions, which can be tested in accelerator experiments. In this region of parameters the νMSM provides a common mechanism for production of baryonic matter and dark matter in the universe. We analyse different fine-tunings of the model and discuss possible symmetries of the νMSM Lagrangian that can lead to them.
    Comments: 56 pages, 16 figures. Many clarifications added, published version
    Subjects: High Energy Physics - Phenomenology (hep-ph); Astrophysics (astro-ph)
    Journal reference: JHEP0808:008,2008
    DOI: http://arxiv.org/ct?url=http%3A%2F%2Fdx.doi.org%2F10%252E1088%2F1126-6708%2F2008%2F08%2F008&v=ec296d9e [Broken]
    Cite as: arXiv:0804.4542 [hep-ph]
    (or arXiv:0804.4542v2 [hep-ph] for this version)

    plus a 4D quantum gravity, either loop quantum gravity or Asm Safe Gravity be considered a TOE? a statement of the most fundamental laws of physics and laws of nature?
     
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Dec 31, 2015 #2
    "plus a 4D quantum gravity"

    This is what I had in mind, when I posted on maline's thread.

    The 2005-vintage NMSM actually fails in at least one respect: the actual Higgs mass turns out to be below the allowed range. I think this also implies that "2005 NMSM plus asymptotic safety" won't fix that problem - I think AS here would just push the mass to the lower bound, which is still too high. NMSM only has two RH neutrinos and has a new scalar for DM; vMSM has no such extra scalar and three RH neutrinos for DM. I wonder if that is the difference.

    On the other hand, vMSM usually obtains dark energy from an extra, 'quintessence' scalar, whereas NMSM just posits a cosmological constant. (Another issue for NMSM+AS would be, the running of this c.c.)

    So if someone wanted to have a completely specified "TOE" to "study" right now, I would suggest vMSM + c.c. + AS, though I don't think that is the TOE, for various reasons.
     
  4. Dec 31, 2015 #3

    marcus

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    That was a good suggestion. IMO Maline should have taken you up on it and gotten more discussion.
    How would you summarize the various reasons you mentioned that vMSM + c.c. + AS doesn't work? (I'm not sure a "TOE" is even possible, might be a wild goose, but assuming such a theory is thinkable : ^)
     
    Last edited: Dec 31, 2015
  5. Dec 31, 2015 #4
    how would LQG affect NMSM higgs lower bound? how would LQG affect vMSM?

    I was thinking vMSM + c.c. + AS could be a TOE, why isn't it the TOE if no SUSY or any BSM is found?
     
  6. Jan 1, 2016 #5

    marcus

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    Maybe Mitchell will reappear and resolve this apparent difficulty. The Standard Model and variants thereof is built on flat, non-expanding Minkowski space. Something with poincaré symmetry.
    But AsymSafe QG deals with the curved spacetime of GR, potentially expanding, without that symmetry.
    In GR time is only defined once you have a solution to the GR equation, causal relations between events depend on a solution, it seems that you do not have the machinery needed to develop Quantum Field Theory, the basis of SM variants like νMSM. You might think you are equipped locally, and any one given point, but the whole thing doesn't gel.

    Mitchell can probably resolve that apparent conflict. I'd be interested to know his reasons for thinking νMSM+cosmological curvature constant+AsymSafe does not work.

    Personally I suspect the quest for a "TOE" is ill-conceived. The Equivalence Principle suggests that gravity is not a force in the usual sense. It is more like an interaction between matter and dynamic geometry. The three fundamental forces are different. I don't know of any analogous "Equivalence Principle" for electromagnetism. So I would not be inclined to expect any "unification" of gravity with the three fundamental forces you have in QFT.

    "TOE" strikes me as a contradiction in terms. Theories are always about a limited subset of the degrees of freedom That is how you get an observer who can interact with, but be separate from, the system being studied. That is how states can be defined, predictions made. F. Vidotto has a nice recent paper explaining this, called "Relational Cosmology". And in a more general sense something that is really a "TOE" seems like a logical impossibility the way an accurate map which includes a map of itself is impossible. Any theory always has room for further refinement and elaboration, is never finally complete.
    (But perhaps you understand "TOE" to mean something else...unknown to me.)
     
  7. Jan 1, 2016 #6
    Marcus has identified a major reason to be skeptical that vMSM+cc+AS is the whole and final truth about physics. QFT is a little more flexible than he says, there is such a thing as QFT in curved space (qftcs). But the usual belief is that there is also a genuinely distinct physical regime of quantum gravity (qg), where the QFT framework of fields on a manifold has to be abandoned for another starting point that only simplifies to "fields on a manifold" in some limit.

    But the AS school of quantum gravity seems to think that qftcs will be enough to describe everything, or at least that you can start from a local, qftcs-style lagrangian - in this case, vMSM coupled to general relativity - and still arrive at a correct description of the qg regime. That may not be possible, but the conservatism of the AS approach, and the extent to which it does work, makes it a fruitful candidate for the "4d quantum gravity" component of a tentative minimal theory-of-everything, such as we are discussing here.
     
  8. Jan 1, 2016 #7
    the lower mass bound for the higgs in The New Minimal Standard Model is 130GEV, just 4 GEV higher. if AS can lower it by 4 GEV then it is still viable. would LQG be able to lower the bound?
    what effects does LQG have on Higgs bounds, stability? AS for that matter.


    what about LQG? it seems also minimal and conservative.
     
    Last edited: Jan 1, 2016
  9. Jan 5, 2016 #8
    LQG is not at the level where you can define vMSM+LQG well enough to make calculations. In particular, the SM, and therefore vMSM, has chiral fermions (individual fermions that are left- or right-handed) coupled to gauge fields, and LQG has a problem with that, a problem already known from lattice gauge theory.

    However, the high-energy running of the Higgs really just depends on the top quark yukawa coupling to the Higgs. So if LQG people wish to tackle this topic, I suggest they consider just the "top-Higgs system" coupled to LQG. They might be able to study that already.

    Haelfix once said, that he thought something like AS is the only way that LQG could work. The problem with naive, QFT-style quantum gravity is that there are infinitely many undetermined coupling constants (corresponding, e.g., to 3, 4, 5... gravitons meeting at one point), and AS would resolve this by showing that in fact there are only finitely many parameters to be specified. LQG has an analogous problem and perhaps needs an analogous solution.

    AS can't move those bounds on the Higgs mass, they depend on the non-gravitational part of the theory. The bounds can change if the particle content and/or other parameters are changed. What AS can do, if conditions specified by Shaposhnikov and Wetterich are met, is cause the Higgs mass to equal the lower bound, the stability bound.
     
  10. Jan 5, 2016 #9
    yes LQG's fermion doubling problem. there are a couple of papers which claim their version of LQG doesn't have that problem and can couple to chiral fermions. in those models how would it change NMSM/vMSM.

    the NMSM could they simply modify it by swapping out the right handed neutrinos for extra scalar for DM to lower the bound to 126GEV from 130GEV.

    regarding the high-running of Higgs how would the hierarchy problem change if there's no GUT scale and the planck scale physics is described by either LQG or AS?

    so Haleifiex was suggesting a merger of LQG with AS?
     
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