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  1. M

    A MOND theory primer

    That in formulating or judging a theory, one should bear in mind the main lines of evidence for dark matter and how dark matter accounts for them, and also the specific successes of MOND and how MOND accounts for those. The first step is because dark matter does more than account for galactic...
  2. M

    A MOND theory primer

    The astronomer Stacy McGaugh has become the most prominent public promoter of MOND (modified Newtonian dynamics) in recent years, on the grounds that it makes many successful predictions, yet according to the standard "LambdaCDM" (dark energy plus cold dark matter) paradigm, there's no reason it...
  3. M

    A New string formulae for Higgs mass and cosmological constant Calculating the Higgs Mass in String Theory Steven Abel, Keith R. Dienes [Submitted on 8 Jun 2021] There are at least two properties of the Higgs mass one might hope to explain with such a fundamental calculation: its criticality, and its participation in...
  4. M

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

    Koide's latest is a five-flavor preon theory! Although he only gets one generation at a time, and needs three further "family preons" to get three generations. And while some composite states are two flavor-preons plus a family preon, others are one flavor-preon plus two family-preons - whereas...
  5. M

    A The long awaited F theory book finally set out

    Not so strange if you think about it: "Applied data science": it's now common for people to use machine learning to search through sections of the string landscape for vacua of interest. Indeed, the author of the F-theory book himself now works as a data scientist. "Paper models": F-theory...
  6. M

    A Reviving Kaluza-Klein

    It's more that the "old" ideas are still far from completely explored. The apex of theoretical orthodoxy is that we are living somewhere in the landscape of solutions to string theory. This idea makes a great deal of sense, and actually brings more order to post-1970s theory than one had reason...
  7. M

    A Reviving Kaluza-Klein Higher-dimensional routes to the Standard Model bosons Joao Baptista [Submitted on 6 May 2021] Higher-dimensional routes to the Standard Model fermions Joao Baptista [Submitted on 6 May 2021]
  8. M

    It's a terrible thing. People understand the human tragedy of how her life ended, but I don't...

    It's a terrible thing. People understand the human tragedy of how her life ended, but I don't think they understand the intellectual loss. We've lost someone who had a unique and valuable place in the ecology of neo-minimalist theorists, and it's not even recognized.
  9. M

    A Just standard model and gravity, up to high energies? An update

    A recurring topic in particle physics, is the possibility of a "desert" above the electroweak scale: no new physics (new particles, new forces) until the grand unification scale or the Planck scale. It's important to remember that the Higgs boson mass was correctly predicted three years in...
  10. M

    Mass in motivic quantum gravity

    Marni Sheppeard, who posted here and in the physics blogosphere as @Kea, is believed dead. I think she was ahead of her time; we shall find out in the coming years.
  11. M

    A Octonions and the Standard Model

    Via @MTd2, I learned that a Perimeter Institute workshop on "Octonions and the Standard Model" has taken place in February. In the final slide of his presentation, Kirill Krasnov foreshadowed a paper that appeared this week, "Spin(11,3), particles and octonions". This is a version of the old...
  12. M

    I M-theory and Calabi-Yau compactifications

    I got confused about the isometry groups for a moment... @bayakiv is embedding one object in another and looking at the isometries of the combined object, I will discuss that in a moment. Normally (in Kaluza-Klein), one looks for a single compact manifold whose complete group of isometries is...
  13. M

    I M-theory and Calabi-Yau compactifications

    There is a difference between the bundles of gauge theory, and the compact spaces of Kaluza-Klein and string/M theory. Those compact spaces are part of space-time, they are extra dimensions of space-time, and in particular the space-time metric is extended to describe them too. On the other...
  14. M

    I M-theory and Calabi-Yau compactifications

    In pre-string Kaluza-Klein theory - where one is dealing with quantum fields rather than strings - the gauge group arises from a symmetry of the compact manifold K. But as I mentioned, the gauge groups in string theory are obtained differently, since most of the K's considered there, don't have...
  15. M

    I M-theory and Calabi-Yau compactifications

    First a detail in the title. d=6 Calabi-Yau spaces are used in d=10 string theory. In d=11 M-theory, to get analogous results, you use d=7 manifolds called G2 manifolds. (If you continue to d=12 F-theory, you use Calabi-Yau again, but now they are d=8.) There are two classic ways to get gauge...
  16. M

    What is new with Koide sum rules?

    Perhaps we should mention the B-decay anomalies. I see two reasons to do so: First, there are anomalies seen not just in b->s but also b->c, and the (b,c,s) triple is at the heart of the Koide "waterfall" discussed in this thread. Second, one might hope that family gauge bosons like those...
  17. M

    I B -> s µµ decays: Current status

    I want to understand this comment (I'm interested in vector dominance), so just to be sure: are you referring in the first part, to @mfb's higher order effects (#28), and in the second part, to the B-meson decay anomalies?
  18. M

    A Fermions and monopoles

    Two papers today: Missing final state puzzle in the monopole-fermion scattering Ryuichiro Kitano, Ryutaro Matsudo [Submitted on 25 Mar 2021] Quark-Gluon Plasma and Nucleons a la Laughlin Wei Lu [Submitted on 25 Mar 2021]...
  19. M

    What is new with Koide sum rules?

    I have to say I still don't understand the fermionic translational symmetry (Friedberg-Lee symmetry) that Xing's paper is based on. The simplest paper about it that I could find, is this by Jarlskog... And if it is to apply to the waterfall as a whole, something has to change since most of the...
  20. M

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

    Some recent explorations: I was worrying about the baryon number of a "quark-diquark superfield". I don't know how it could be, that the fermionic and bosonic components of a supermultiplet, could differ in quantum numbers other than spin. In looking around, I discovered that Miyazawa's 1966...
  21. M

    A The Langlands program and its connection to physics

    Among the generalizations of number theory, one can ask about twin primes, zeta functions, etc, in the context of "function fields", which are actually algebras of polynomials (the elements of these fields are expressions like (x^2 + x + 1)/(x-1)). The Langlands version of this, "Geometric...
  22. M

    What is new with Koide sum rules?

    A curious paper from China today, "A translational flavor symmetry in the mass terms of Dirac and Majorana fermions" by Zhi-zhong Xing. The symmetry in the title is a "discrete shift in flavor space" whose definition I don't understand, but it has two consequences of interest. First, it implies...
  23. M

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

    I have just run across a 2019 paper from Japan that we seem to have missed, "Dynamical supersymmetry for the strange quark and ud antidiquark in the hadron mass spectrum". As with hadronic supersymmetry, this is not about fundamental supersymmetry, it's about an emergent symmetry that involves a...
  24. M

    I Constrains on experimental space and parameters

    If I understand the question correctly, you're asking what possibilities remain for new fundamental forces or fields, given experimental constraint. This is extremely broad, the search for new things is a huge part of experimental particle physics. Many possibilities are not categorically ruled...
  25. M

    I General Relativistic Quantum Theory?

    There's no doubt that over the years, people have tried out this starting point. There are decades of formal speculations recorded in journals like "Foundations of Physics". You could find some by googling "general relativistic quantum". But once you decide to start this way, it's still only the...
  26. M

    I Einstein's purely algebraic physics and "my entire castle in the air"

    This reminds me of the claim that 2+1 dimensional gravity in AdS space, for a particular AdS radius, is holographically dual to the Ising model (more specifically, dual to the CFT describing the critical point of the Ising model). Is there a three-dimensional counterpart of using Q_8 to describe...
  27. M

    I Kerr black hole, time genre loop, Tipler's cylinder

    This honors thesis talks about CTCs for both Kerr black hole and Tipler cylinder. You can find more about the Kerr case if you google 'Kerr metric CTC'.
  28. M

    A Octonions and the Standard Model

    From this celebrated review (1445 citations according to Google Scholar), I have learned that ##\mathbb{O}\mathrm{P}^2## can be realized via equivalence classes of certain elements of ##\mathfrak{h}_3(\mathbb{O})##. The elements of each such equivalence class are simply real scalar multiples of...
  29. M

    A A Proposed Black Hole Entropy Calculation

    Thanks to @Haelfix for his reply. I don't know if I'll ever get time to think this through, but here are some references I would use, to start trying to understand what's going on in the 2d case. My focus would be on two preprints from a year ago, described by Quanta magazine as from East...
  30. M

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

    Well, the idea of the sBootstrap in its essence (please correct me if I misrepresent it:smile:) is that by considering superpartners of diquarks and mesons formed from the five light quarks udscb, you get all the fundamental fermions of the standard model. So first you have to add supersymmetry...