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  1. M

    The wrong turn of string theory: our world is SUSY at low energies

    A year ago, while we were puzzling over what to do with single-flavor diquarks, I wrote Now Avner Karasik, mentioned in this thread at #269-270, has obtained the one-flavor eta membrane as a limit of a two-flavor skyrmion, by slightly amending the usual baryon current. He remarks (just after...
  2. M

    A New model of high-spin Baryons

    "Skyrmions, Quantum Hall Droplets, and one current to rule them all" by Avner Karasik obtains this unusual Nf=1 (one-flavor) model, as a limit of a more conventional Nf=2 skyrmion model, in which one flavor becomes heavy. The key technical development is in equation 4.9, a new current H which...
  3. M

    A M theory dimension change and large N_c, are they related?

    In terms of AdS/CFT, one has N (as in SU(N)) and g (gauge coupling) to work with. In string theory, the eleventh dimension emerges when string coupling is large, and string coupling is proportional to g^2. So at first glance there is no relationship, though in practice there are limits defined...
  4. M

    I Conserved quantities

    Google '"two time" noether' for theoretical work on this topic.
  5. M

    The wrong turn of string theory: our world is SUSY at low energies

    Two more papers: Stanley Brodsky provides another review of his light-front holographic QCD. LF hQCD is meant to be a new paradigm for a great many aspects of QCD - e.g. in his section 2, he says it offers a distinctive perspective on the origins of confinement and the QCD mass scale - but our...
  6. M

    The wrong turn of string theory: our world is SUSY at low energies

    I have no time to discuss or analyze, but MSSM guru Stephen Martin has written a paper, "Mixed gluinos and sgluons from a new SU(3) gauge group", which looks like a more orthodox analysis of some of the U(3)^n / SU(3)^n possibilities I mentioned in #289.
  7. M

    A Explaining the Hubble tension with fundamental physics

    For the record, "H0 Tension and the String Swampland" claims to implement the Agrawal-Obied-Vafa "fading dark matter" proposal, using a particular (4+2)-dimensional geometry (Salam-Sezgin) that might come from 5-branes (and the standard model would e.g. come from a 3-brane in this background)...
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    The wrong turn of string theory: our world is SUSY at low energies

    "Hadronic Strings -- A Revisit in the Shade of Moonshine" by Lars Brink takes us back to the beginnings of string theory as well as the beginnings of this thread. He takes us through the attempt to develop a "dual model" (as string theories were originally known) for mesons made from the light...
  9. M

    The wrong turn of string theory: our world is SUSY at low energies

    "U(3)xU(3) Supersymmetry with a Twist" by Scott Chapman of Chapman University (the university is named for one of his ancestors) proposes to get "two families of Standard Model left-handed quarks" from the gauginos of N=1 supersymmetric U(3)xU(3) gauge theory, in a way that resembles (page 4)...
  10. M

    What is new with Koide sum rules?

    Koide and Nishiura have posted another installment of their U(3)xU(3)' universal seesaw model (in this thread, see posts #156, #182 for previous papers). But that is a technical refinement in one particular, rigorously defined BSM theory of theirs. I find much more intriguing, the updated...
  11. M

    A Donoghue's critique of asymptotic safety

    I have not read this paper yet, but Lubos Motl blogs about it here: "A serious critique of the real-world Asymptotic Safety program for quantum gravity". The points I would list in favor of asymptotic safety's significance and viability, may be found in this Physics Stack Exchange...
  12. M

    I Tom Banks' New Paper - Contra Eternal Inflation

    I agree with you both, to some extent Banks's criticisms are self-contained and certainly don't rely on the existence of HST as an alternative. As to their merit, I haven't had time to develop an opinion of my own. I do think that, sociologically, Susskind and Vafa are now the leading...
  13. M

    I Tom Banks' New Paper - Contra Eternal Inflation

    Tom Banks has been writing papers like this for many years now - I posted about one, seven years ago. I would put it in context like this. In string theory - Banks is a string theorist - perturbative string theory (based on the stringy version of Feynman diagrams) provides a model of quantum...
  14. M

    I Problem of time in quantum field theory?

    @PrashantGokaraju says a number of intriguing intuitive things in this thread. They deserve a broader response, but I will just focus on two things. First, on de Sitter and Chern-Simons, this comes from Smolin 2002 and drew a response in Witten 2003. Second, @Demystifier is correct that...
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    The wrong turn of string theory: our world is SUSY at low energies

    Two September papers: An attempt to realize Brodsky et al's "light-front holographic QCD", mentioned many times in this thread, within a proper string theory! But the paper will require closer study (than I have had time to give it), in order to see what's really going on. LF hQCD is based on...
  16. M

    A Merging Gravity with the other forces

    I gave my answer to this question at Physics Stack Exchange a few years ago. The highest-voted answer there may also help.
  17. M

    I Efficiency of computers vs. brains

    @Flisp (#11) is getting to the point. One needs to compare what actually happens when humans do arithmetic and when a computer "does arithmetic". Typical humans have memorized addition and multiplication tables for single digits, and then have procedures that they follow for arithmetic tasks...
  18. M

    A Could this unified theory be correct?

    They do not predict, or even retrodict, the correct mass. They only show that it lies within their parameter space, see figure 2. The only noncommutative model that directly gives the right mass, is one by Marcolli and a student, which uses the mechanism of asymptotic safety (as in Shaposhnikov...
  19. M

    A Membrane theory

    That's a duality between strong and weak coupling. It's called S-duality if it is in string theory, or in a field theory that derives from string theory. From memory, the SO(32) heterotic string is S-dual to the D1-brane of Type I string theory; but that's just how it works in that particular...
  20. M

    A Masses from modular symmetry

    Here we have some physics numerology using modular forms. The authors just take matrices appearing in the theory of modular forms, and use them to approximate the standard model mass matrices, without having a definite physical framework. I don't believe their specific proposals because Koide...
  21. M

    I What follows after SUSY

    As far as I know, the first supersymmetry in physics was proposed by Miyazawa in 1966, to place mesons (bosons) and baryons (fermions) in the same multiplet. Then at the start of the 1970s, it was found mathematically within string theory and field theory, but not yet with any application in...
  22. M

    The wrong turn of string theory: our world is SUSY at low energies

    Some recent papers... June: Sonnenschein et al develop Sonnenschein's HISH model (holography inspired stringy hadrons). "Unlike in the usual string theory, in which the modes of open strings correspond to fields of the standard model or other QFTs, here we associate them with the states of...
  23. M

    I Why don't strings have a Planck mass?

    I believe that statement is wrong - that it is an attempt to simplify the logic of string theory, which ends up actually misrepresenting it. You can motivate the form of the mass operator, by expressing the momentum-energy of a classical string, in terms of its oscillation modes. When you go...
  24. M

    I Why don't strings have a Planck mass?

    First, something of a technical detail - very important for actual string theory, but a detail with respect to your argument: In the standard model, in the absence of the Higgs field, all the elementary particles are actually massless. The Higgs field interacts with itself in such a way that...
  25. M

    A Gravitational dressing in quantum field theory

    In quantum field theory, a dressed particle is a particle ("bare particle") considered in combination with certain secondary effects that it produces (e.g. the virtual pair creation involved in vacuum polarization). The dressed states are regarded as more physical, hence closer to reality. Axel...
  26. M

    A Explaining the Hubble tension with fundamental physics

    The Hubble tension or Hubble discrepancy is a contradiction between the Hubble constant as measured today, and the Hubble constant as measured in the early universe and extrapolated to today. @mfb recently listed the relevant measurements. There are some threads about this in the Cosmology...
  27. M

    A Scientists are searching for a mirror universe...

    This is not actually a multiverse theory in any sense. It is a theory that the particles of dark matter are more or less in 1-to-1 correspondence with the particles of the standard model - there would be dark quarks and dark leptons, interacting via dark gauge bosons. But the particles of this...
  28. M

    B Strong nuclei force and extra dimensions

    Yukawa found the right explanation in 1935, in this paper: the nuclear force between protons and neutrons decreases with the square of the radius, times an extra factor which makes it drop off exponentially. The extra factor is because the force particle is massive (whereas the photon of the...
  29. M

    What is new with Koide sum rules?

    On Dr Koide's personal website, there is a July 6 update in Japanese (you may need to switch your browser's encoding to see it properly), in which he expresses regret for not updating the website more often, and says that he has been in poor health for the past two years. Physics research is the...
  30. M

    A New model of high-spin Baryons

    In April, Komargodski gave a talk about this ongoing work (video, slides). He says (video, 36m50s fwd) that sheets of eta-prime condensate have been discussed before, in the context of high density and high "chemical potential", e.g. inside neutron stars, but "people have completely missed the...
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