The Quiet Higgs Quake at CMS

Posts have been a bit rare due to overwork and travel, but I have a few things to say about the search for the Standard Model Higgs particle (the simplest possible form of the Higgs) at CMS, one of the two major Large Hadron Collider [LHC] experiments.   Last week I focused on the big news from the Tevatron and from ATLAS (the other major LHC experiment involved in the Higgs search), because the changes in their results were much larger than those from CMS, partly because CMS had already analyzed all their data for all of the different types of Higgs decays, and also the changes at CMS were, on the face of it, rather small.

However, the results at CMS have a significant effect on the overall picture, both negative and positive, and so deserve comment.

The main change from the December and January CMS two-photon Higgs search is that a more powerful and sophisticated technique has been applied to the same data. The results are roughly consistent with the previous search, but show important differences (which tells you how sensitive the current evidence is to how you slice the data.) Here are the consequences of the new result compared to the old, illustrated in the two figures late in the post:

  • A new exclusion region, not only above 125 GeV/c2 as they had before, but now also below it, from about 117.5 GeV/c2 to 120.5. Again, this is very good news if you think there is a Higgs somewhere around 125 GeV/c2, because it is a lot more persuasive that you see a Standard Model-like Higgs at 125 GeV/c2 if you can say more convincingly that you don’t see it anywhere else.
  • The significance of the Higgs hint in the data actually stayed almost the same with the improved techniques, whereas if there had been a real signal there before with the older techniques, you would have expected an increase in the significance. We now see 2.9 standard deviations [or "sigmas"]  locally (i.e., without look-elsewhere effect) and 1.6 with the look-elsewhere effect (versus the previous values of 3.0 locally and 1.8 with look-elsewhere accounted for.)  But this is because the size of the excess went down a little.
  • The collisions with two photons were divided, as was the case in the CMS January update, into those that have two jets and those that don’t. (Actually, to be precise, the division separates out those that have jets that are consistent with the process p p > q q H ["vector boson fusion"] — see this article on Higgs production — and you must remember that a large and extremely uncertain fraction of these are actually from p p > H ["gluon fusion"] with two radiated jets.) The new result shows that the majority of the 2.9 sigma excess is now coming from the handful of two-photon-two-jet events; this makes the significance subject to large fluctuations with future data, so don’t be surprised if it moves around a lot in the next update.
  • BUT the new CMS analysis puts its best value for the Higgs mass at 125 GeV/c2, whereas previously it was at 123.5. The ATLAS result has put its best value a bit above 126. Such shifts are not unexpected, and we’ve been waiting for them, as I have emphasized (here and here).  Of course a shift could go in either direction, and one reason for my caution about the LHC results has been that it was perfectly possible the shifts would go in the wrong direction, pushing the ATLAS and CMS results apart and causing the entire case for the Higgs at 125 to collapse. But this shift is in the right direction. The ATLAS and CMS results are now in more accord, favoring values of the Higgs mass that are closer together than before.And that too is good news for the hypothesis of a 125 GeV two-photon Higgs signal.

Fig. 1: The old (left) and new (right) CMS two-photon analyses of the same data, showing how well a signal from a Higgs of given mass can be excluded, in units of what is expected in the Standard Model. There is a new excluded region (purple oval) where the exclusion region drops below 1 (the expectation in the Standard Model.) Looking at the red line, you can see the peak excess has decreased in size. Its statistical significance has remained about the same (see Figure 2). The peak has shifted from 123.5 to 125 (blue line) bringing it more into accord with ATLAS's excess.

So I think one can say that the concern was justified; a large shift was indeed quite possible.  But fortunately for the evidence, the current seismic shift at CMS created stronger, not weaker, alignment with ATLAS.

And so, even though the evidence at ATLAS went down somewhat, despite more analyses being added, and the evidence at CMS didn’t increase as it might have been expected to, given the better two-photon analysis — the evidence is overall a bit more plausible in my book. While each experiment sees reduced evidence, collectively their evidence is more consistent than before with a Standard Model Higgs at 125 GeV — and they have improved evidence against a Standard Model Higgs appearing anywhere else.

To this one must add the new Tevatron data, with care, since DZero and CDF don’t see the same thing, and since the significance isn’t large, and since (see the Fermilab talk on the CDF result, which has far more information about this than the Moriond talk — note especially the pages around page 56) the CDF excess is driven larger than expected by a small number of events.  My point of view is that one should simply say that Tevatron data roughly supports the LHC evidence and leave it at that.

All in all, my confidence in there actually being something real at 125 GeV has gone up. I have been heard complaining about the lack of exclusion below the 125 GeV region and the fact that ATLAS and CMS were far enough apart that a shift of their best-estimate of the putative Higgs mass might easily make them inconsistent. Now we have some nascent exclusions from both experiments, and the best estimate of the Higgs mass at CMS has indeed shifted toward ATLAS. So — the game isn’t over, but it looks a bit more like a winner to me now than it did before.

Fig. 2: Old (left) and new (right) plots showing the local statistical significance of upward excesses above background; read the number of standard deviations (sigmas) at the right of each plot. Notice that the total significance (black lines) around 125 GeV has gone down slightly, but this is because the two-jet-two-photon category (red lines) has become slightly more significant, while the excess in the remaining events (blue lines) has become somewhat less significant. Note also the preferred mass has shifted from 123.5 to 125, due to a small shift in the dominant red category and a loss of mass resolution in the subdominant blue category (which only weakly prefers 125 over 123). Notice also the bump at 136 GeV has become much more significant; this is presumably a fluke, but emphasizes that the CMS Higgs hint is also not that unusual on its own (i.e. it can only become persuasive if one simultaneously looks at ATLAS data.)

33 responses to “The Quiet Higgs Quake at CMS

  1. Hi Matt,
    Could you comment on the lack of excess in h->WW in both ATLAS and CMS? Should we worry about that?

    • I think the only question which will have a clear answer is whether we have a bump in the search for two photons and/or four leptons. The WW, bb and tau tau measurements are difficult because they involve searching for broad excesses on challenging backgrounds. At the level of precision available and given the accuracy required, it’s not so hard to imagine creating a false signal or removing a real one. I don’t think we can draw clear conclusions yet. We need more data.

  2. Pingback: Un resumen sobre el estado de la búsqueda del Higgs tras la conferencia de Moriond EW 2012 « Francis (th)E mule Science's News

  3. Hello Prof Strassler,

    Excellent articles and speeches, I might add. I am from an engineering background and have been fascinated, like a great mass of informed people around the world, on this honest surge in the search for God, sorry God’s particle, sorry again Higg’s boson. :-)

    So many questions and so little time, as they say, but like anyone who can close to understanding QM has a theory of his/her own and that includes yours truly. I will not bore you with my take but I would like to ask you a question about the top quark, (and somewhat a similar question would apply to the neutrino, but I will defer that until the jury is out at OPERA). I one of you blogs you mentioned:

    “The top-left quark and the top-right quark interact strongly with each other and the Higgs particle… and not with other matter particles. In particular, if a top-left quark encounters a Higgs particle, it can turn, with high probability, into a top-right quark. Once the Higgs field is non-zero, this type of interaction causes the two versions of the massless top quark to become a single massive top quark, with a large mass.”

    I am not sure I agree with the notion that the top quark remains a “single” elementary particular after the “combination”, unless the process is irreversible. What is the mechanism that destroys the distinct characteristics of the three components and produces one indistinguishable “particle? And, If the combination process is irreversible wouldn’t that contradict the SM itself?

    My deeper question would be since both the top-left and the neutrino can change flavor when they encounter the non-zero Higg’s field ( or a similar mechanism) then could that be suggesting that energy is coalescing to a threshold, just before a Higg’s field becomes non-zero (symmetry breaking) and then collapse back down to the lowest uniform density. This oscillations continue until adjacent oscillations interact (via Higg’s or some other mechanism) to push it above the theshold and hence create a stable soliton, one of the fermions and/or other bosons?

    I can see a superluminal neutrino in my above theory, since the shell of the quanta space would have a normal distribution in density and hence would be superluminal on one side of the shell ‘wall”.

    Am I whistling Dixie? :-)

    • A physics theory is a set of equations, not a set of ideas. [Think of Newton's laws; Newton didn't say "I'll bet that if you push on something, it speeds up, and the heavier it is, the less it speeds up"; he said " F = m a ".] A set of ideas without equations is a speculation. If you can turn it into equations, and show the equations make predictions that are consistent with existing data, you’re doing theoretical physics. With less than that, you’re just shooting the breeze.

      So I am afraid I couldn’t possibly evaluate your theory as it is now; there’s nothing to evaluate. I don’t understand your words. What’s a soliton? A soliton of what field? Oscillations of what, and with what frequency? What threshold are you talking about? It’s all very vague, as language always is.

      Give me some equations, and we can talk.

      You say “I am not sure I agree with the notion that the top quark remains a “single” elementary particular after the “combination”, unless the process is irreversible. What is the mechanism that destroys the distinct characteristics of the three components and produces one indistinguishable “particle? And, If the combination process is irreversible wouldn’t that contradict the SM itself?”

      Well, there are only two components (the top-left and the top-right — the Higgs is not a component, if that’s what you meant by the third of “three”) and in Dirac’s famous equation for a massive fermion, the merging of these two components into one is exactly what happens. If you turn the mass off, the flip-flopping stops and you get either top-left or top-right. If you turn the mass on, the flip-flopping starts and you can’t have top-left without also having top-right; the top quark is a mix of both. It’s all very precise, as the best equations always are.

      • Of course, as fully as I agree with your point “equations, equations, equations”, I can’t resist pointing out that Newton didn’t actually write “F=ma” and was distinctly more vague with his laws than any of us would like to be.

        • Thanks, James, for the comment and for pointing out the anachronism on my part. I am, of course, overstating the point. As are you, for effect… We will both agree that Newton was always much less vague than a typical amateur, and his mathematics — well, the guy had equations he needed to solve, so he invented calculus to do it.

          But any physicist isn’t merely clear and precise, because when a research paper is written there are always things that are well-understood, many other things poorly-understood, and then there is the topic of the paper, which is something that ideally is being transformed from poorly- to better-understood.

          What a professional really does is draw a figurative circle around the research area and push to the side things that are irrelevant and things that are unclear. Within that circle, a clear and detailed discussion follows. When this is done well, a new peninsula of knowledge emerges from the great sea of things unknown, and attaches itself to the continent of what is already known or suspected.

          One aspect of being a professional is understanding, partly from intuition and partly from deep understanding, how to do that. And Newton certainly knew.

          I should also add that many physicists are not as clear as Einstein when they write; some of them think very clearly and brilliantly but have trouble expressing their thoughts to others. My colleague Lipatov is a famous example; few people understand his papers when they first appear but they are almost always both right and important. But he has a track record going back decades.

  4. Again, this is an excellent update for Higgs.

    There were talks on SUSY, top physics and stops at Moriond conference. Can you elaborate them some?

  5. But the new plot also displays a spike almost of the same size at the mass of 136 GeV (already exluded, by the way). Since at least one of the two HAS to be wrong, this signal doesn’t look so promising for me.

    • That’s right; I referred to that in the Figure caption. You would not think there was anything special at 125 if there were not ALSO a spike in the ATLAS plot at the same place. Neither ATLAS nor CMS is convincing at all on its own; only ATLAS and CMS together provide some evidence, but (I would say) not convincing at this time. I’ve been saying that all along, and I don’t think things have changed too much yet. It’s only because I was so cautious before that I think things have improved.

      But ask Tommaso Dorigo over at Science 2.0 what he thinks; he’ll tell you the evidence for the Higgs is firm and discovery at 125 is basically certain at this point.

  6. “A physics theory is a set of equations, not a set of ideas.” I disagree. The equations are the cart but the ideas are the horse. Einstein first thought of the equivalence principle and then developed his field equations.

    http://en.wikipedia.org/wiki/Introduction_to_the_Higgs_field

    The Higgs field is like the luminiferous aether in that it pervades all of space and is difficult to detect. I suggest that the Higgs field is impossible to detect. Consider two opposing hypotheses:
    Hypothesis 1: Virtual quarks have mass because they travel through, or interact with, the Higgs field.
    Hypothesis 2: Virtual quarks do not travel through the Higgs field, because they are quantum probability waves, and such waves do not travel through spacetime. Virtual quarks do not interact with the Higgs field, because if they did then they would be real quarks and not virtual quarks.
    Why do virtual quarks have mass? I suggest that whatever the reason might be that virtual quarks have mass, the reason has nothing to do with the Higgs field because the Higgs field is a wrong idea. I suggest that virtual quarks have mass because the Wolframian mobile automaton creates approximations to space, time, energy, and mass using a network of information below the Planck scale. The Rañada-Milgrom effect is approximately true because an overwhelming mass of empirical evidence says it is approximately correct. Wolfram’s idea look good qualitatively, and equations shall (perhaps) eventually back them up.

    • At some level, Mr. Brown, your answer speaks for itself.

      Ideas are the horse, yes, but the cart carries all the weight. There’s a reason why it is horse-and-cart, not horse-now-and-cart-six-weeks-later.

      Your mistake — the classic mistake made by most people — is in thinking the theory is the horse. The theory is the cart. The horse is the insight, the idea. The idea and the insight make the theory possible. But an insight is not a physics theory.

      Your example of the equivalence principle is an interesting one. I think you need to read a lot more scientific history.

      Einstein’s first paper on the equivalence principle, translated here

      http://www.pitt.edu/~jdnorton/teaching/GR&Grav_2007/pdf/Einstein_1907.pdf

      contains the statement of the principle, at the very end of section 17. Immediately following — the entire remainder of the same paper — he sets out to establish precise mathematical and physical consequences of this principle, in clear and precise language.

      Section 18 is all aimed at deriving equations (30) and (30a). Section 19 derives a precise statement about clocks from those equations. Section 20 is aimed at the derivation of the precise equations in (31a)-(32b), and their consequences, including the two following unnumbered equations, which show that the equivalence principle combined with special relativity implies that gravity must pull not on rest mass but on total energy (mass-energy + motion-energy); this is one of the first steps toward general relativity.

      It is all those equations that make this paper publishable. The horse without the cart would never have been accepted by a professional journal, and Einstein would have been embarrassed to try to impress his colleagues with just an idea. After all, do you really think that generations of people before Einstein had never noticed that the “m” that appears in F = m a is the same “m” that appears in F = G m M / r^2 ? What makes Einstein’s paper great is not the idea; it is the fact that he is smart enough to take this idea, combine it with special relativity, and derive precise and interesting consequences in the rest of the paper.

      It’s all very precise. I can read this paper line-by-line and reproduce the argument and, with some work, the equations.

      What you learn from this is:

      a) Einstein was a professional physicist, and knew the difference between an idea and a step toward making it a real theory — horse versus cart.
      b) Einstein knew how to write papers that other professional physicists would take seriously: don’t bother people with your horse unless it is attached to a cart that actually has something in it.
      c) Einstein was able to express his ideas clearly and explain to other professionals how he got his equations; they don’t come out of thin air, they are derived step by step. The cart isn’t made from cardboard, but from steel. Where there are assumptions, they are clearly stated and well motivated.

      It is very easy for a professional to recognize an amateur: there’s far too much emphasis on the horse, and not enough on the cart; equations appear out of nowhere, without clear justification; the language is vague instead of being highly precise. In Einstein’s paper, there is not a single vague or ambiguous line.

      • A question to equivalence that has bothered me:
        release two objects in an accelerated rocket and they “fall” along parallel paths and never meet
        drop two objects in a gravitaional field and the paths of their fall converge to the centre of gravity
        it would seem there is a clear difference between the two – or not? – please explain (without too many equations) – thank you
        Zbynek

  7. “Forgive me Father for I have sinned.”

    As an amateur I only brought up the idea of repeatedly collapsing “solitions” because it could be a way, mechanism, for explaining the gravity field (and not the Higg’s field) within the context of the SM.

    Repeatedly collapsing solitons, the reverse or inverse of Newton’s cradle, if you will.

    • It’s a matter of standards. Historically, people who pushed science forward had the highest standards; if you want to participate, you’ve got to raise your own to the same level.

      I am afraid I understand your last message even less. How could repeatedly collapsing solitons be a mechanism for explaining the gravity field within the context of the Standard Model? What’s the relationship between these things, precisely? I know a lot about solitons. I know a lot about gravity. Help me out here.

      I gave a Newton’s cradle to my little nephews this year. What is the reverse, or inverse, of this cradle? What does this have to do with repeatedly collapsing solitons?

      Be precise, and clear; emulate Einstein.

      • http://www.pks.mpg.de/~henkel/Articles/arXiv:1102.2121.pdf

        Abstract:
        “We propose a scheme for the creation of stable three dimensional bright solitons in Bose-Einstein condensates, i.e., the matter-wave analog of so-called spatio-temporal “light bullets”. Off-resonant dressing to Rydberg nD-states is shown to provide nonlocal attractive interactions, leading to selftrapping of mesoscopic atomic clouds by a collective excitation of a single Rydberg atom pair. We present detailed potential calculations, and demonstrate the existence of stable solitons under realistic experimental conditions by means of numerical simulations.”

        “Self-trapped nonlinear waves and the possibility to create ”particle-like” wave packets have fascinated scientists over the last decades [1–4]. In nonlinear optics, the creation of stable three-dimensional bright solitons − so called ”light-bullets“ − has been under active pursuit [4], but was realized only recently in a discrete setting of waveguide arrays [5]. One major obstacle stems from the fact that nonlinear confinement usually comes hand in hand with collapse instabilities [6]. In principle, this problem can be overcome via nonlocal nonlinearities, where the nonlinear self-induced potential at a particular point in space depends also on the nearby wave amplitudes. …”

        “In conclusion, we have shown that off-resonant dressing of BECs to attractively interacting Rydberg states provides a promising route for the first realization of stable self-trapped three-dimensional solitons. While we chose Rb(nD3/2) atoms as one relevant example, the proposed scheme generally applies to Rydberg states of any atomic species with sign-definite attractive van der Waals interactions. …
        In addition, we have shown that a simple isotropic model potential captures the essential physics of the observed soliton formation, which may be useful for future theoretical studies on, e.g., 3D soliton interaction or higher-order states. On the other hand, the anisotropy of the interaction together with its tenability may open new routes to transfer angular momentum.”

        Now, take this mechanism down to the quantum level, below Planck’s scale and replace the BEC’s with Dirac spinor just before the “mass is turned on”, the threshold. If the coalescing energy spherical space collapses because of the inherent instability in the transition between order (gravity field) and chaos (free energy), then there will be attractive interactions between adjacent collapsing spaces, the momentum transfer in inwards towards the center of each sphere, (inverse to Newton’s cradle where the momentum is push outwards towards the center of the next spherical ball.) There vacuum instabilities that create the gravity field are possible due to the energy coalescing on a non-linear spinors, the shell wall has a density profile which is of a normal distribution cross section and hence unstable when interacting an adjacent spinor.

        The sixty four thousand question in my amateur mind is what happen at and/or shortly after the Big Bang that pushed the coalescing process beyond the threshold and “turn the mass on”. In other words was the universe destined to cool down because of the lowering of the local energy densities or was it a freak of nature that the universe started with a small but non-zero entropy.

        • So — everything in the passage you quote is clearly written by a professional. It’s precise and clear. I don’t know the details without reading the paper, but one clue is that every bit of jargon fits with the bit of jargon next to it. Makes sense. I think I know what the author is saying; I’m confident I could understand it if I read more.

          Moreover, there are equations, plots, evidence of serious work. There’s a lot more than a horse, and there’s a lot in the cart.

          Being able to quote other people’s papers, however, does not make your ideas sensible.

          When we get to the first line of your own statements, everything instantly crashes. “Replace BEC condensate with Dirac spinor”. What? A BEC condensate is a boson; a Dirac spinor is a fermion; the physics and mathematics is completely different. You cannot just replace one with the other. So what are you saying here?

          Then at some point you say:
          “vacuum instabilities that create the gravity field are possible due to the energy coalescing on a non-linear spinors”

          I think this is mathematically false. I not sure you have a clear definition of “non-linear spinors”. I do not think even you necessarily know what “energy coalescing on a spinor” means [give me a precise definition.] And any hope for your idea to turn into a real theory requires that you prove that this is true. So I hope you have a good idea here as to how to make equations out of this. I certainly don’t see one yet.

    • Sorry Soap-Bubbles,

      but Your own comments (not the stuff copied from the arxiv-Paper) vaguely remind me of a funny joke a very talented (in maths and physics) classmate played some years ago (I dont know why this is) :-):
      To annoy the poor teacher of our German class, he spiced his essay with a lot of physics and maths jargon appearing at random places, which made the assay a very funny reading (similar to Warren Siegel`s joke papers but not that advanced…),

      Cheers

      • Well — I think perhaps you’re a little unfair to Soap-Bubbles here. His jargon is not random; I can tell he has a real intuition in his head that has some level of coherence, even though it’s challenging (as it is for any amateur) to express it in scientific terms.

        What is really difficult for amateurs to understand — and I know this, because it was hard for me to understand it when I was an undergraduate — is just how difficult it is to take intuitions and ideas and turn them into equations that actually work. Popular science articles on people like Newton and Einstein tend to obscure this point; they discuss the wonderful ideas and downplay the mathematical advances that were essential to progress. And that’s unfortunate, because (a) it makes science seem easier than it is, diminishing the genius of those who make the great leaps, and (b) it makes amateurs focus on the wrong things, and (c) it makes it confusing why science moves so slowly. Why did it take decades to go from Kepler to Newton? Because it took both a revolutionary set of ideas and a revolutionary approach to the math, which had to be developed together. It is relatively easy to have clever but vague ideas. It is extremely hard to make those ideas into equations that you can show are self-consistent, can calculate with, and can compare with data. And typically it requires many small steps and missteps along the way.

  8. Matt you are so right, without equations it is really not physics. In fact, if you are lucky enough to get things ‘right’ odds are that in the end all that is left is the equations! For example, much of Newton’s physics has passed away in the light of Einstein – but the equations remain and are as good as they always were WITHIN THEIR DOMAIN OF VALIDITY – low speeds and weak gravity. When NASA launches space craft they still use Newton. You can expect the same to happen to Einstein one day. The description of reality of the theory that replaces Einstein may well be very different from Einstein’s, but the equations MUST reduce to Einstien’s within the areas where Einstein has already been well tested. And so it goes…

    Anyway Matt, just wondering: At this point in the Higgs data, how do they know it is actually the Higgs lurking at 125 GeV. For example, suppose that there was a 4th charged lepton even more massive and shoter lived than the Tau, could they be be sure (at this point) that an x anti-x lepton pair had not been created rather than a Higgs?

    • I couldn’t agree more with your first paragraph. Physics is about making predictions of some reasonable precision, which is only possible with equations, and not with words.

      A fourth charged lepton wouldn’t do the job; it would not give you a localized excess in two photons. [I am not sure why you think this particular example could do that.]

      However, we certainly are *not* sure that what is being seen, if we assume it is a real effect, is a Higgs particle. One of the jobs of theorists is to think of all the alternative possibilities, and there have been dozens of papers about this in the distant past and recently. Indeed I heard a new one this week while I was at Harvard, during a talk by a Stanford postdoc who was visiting.

      But if we see a bump BOTH in the two-photon search and in the two-lepton/two-antilepton search, then we will be almost certain that it is a Higgs. This is for reasons that I described in my articles on the Standard Model Higgs particle http://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-standard-model-higgs/seeking-and-studying-the-standard-model-higgs-particle/ ; essentially, any particle that has a mass of 125 GeV and has such a large decay rate to two Z particles (one real, one virtual), but not a huge rate to decay to two photons, must be a type of Higgs particle.

  9. Matt: When Einstein uses the phrase “First we take our measuring tools …” he assumes ideas developed by physicists about measurement. Ideas about measurement are more important than ideas about theory are more important than mathematical equations. Mathematical equations without ideas are not much more than code in a computer. When you disparage my ideas you are assuming that my predictions are wrong.
    [Edited by host to remove links to commenter's papers]
    I predict that some physicists who are not excluded from refereed journals will get credit for ideas that I thought of first. I say that Wolfram is a far better physicist than most Nobel prize winners in physics. Perhaps I am wrong.

    • You are welcome to your predictions; I wish you well. Very few predictions, even by professionals, turn out to be correct.

      However, I must ask that you stop advertising your work here; you are too far outside the mainstream, which is what this site is devoted to. You are welcome of course to start your own website for that purpose.

      By the way, you probably know that Wolfram *is* a professional physicist, trained in the same research area as I am trained in. He wrote a number of papers in particle physics. He’s certainly very smart. He isn’t dismissed out of hand. I very much doubt that his New Kind of Science is as revolutionary as he thinks it is — he may be a better salesman than physicist, in the end — but I don’t view it as entirely out of the question. One thing that is for sure: he does understand horse and cart, and knows when something is just an idea and when it’s actually a theory.

      Another trained physicist is Nathan Myrhvold. It’s not an accident that he actually gets things done. What you learn as a physicist is to dump all the fluffy talk and cut to the chase.

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  11. If understanding the Higgs field is the end goal and if the energy density of the Higgs field contributes to gravity, then would be critical to assume that the hypothetical Higgs particle is massive (in other words, is not a boson). Why in the mathematical formalism for the gauge invariance the bosons are considered massless particles? The Higgs entity is massive, it may be formed for bosons, but the entity is something else. I think that the Higgs is an atom or a field of them, having those atoms a similar structure.

    • The energy density of the Higgs field does not contribute to gravity, so I’m afraid your premise is off.

      The energy density of the Higgs field can contribute to the energy of the vacuum, which itself can cause a gravitational effect. But that’s true for lots of fields; nothing special about the Higgs there. And the energy of the vacuum is not the gravity; gravity reacts to the vacuum energy. A (sufficiently large) positive vacuum energy causes the universe’s expansion to accelerate.

      Whether the Higgs field contributes energy density to the vacuum has nothing to do with what the Higgs particle, a ripple in the Higgs field, is doing. It is the Higgs particle that we call the “Higgs boson”. In principle, a field may contribute energy density to the vacuum and yet its ripples are massless bosons; it may contribute no energy density to the vacuum and have a massive boson as its particle. These two issues, (a) the contribution of the field to the vacuum energy density and (b) the mass of the particles that are the ripples in that field, are completely unrelated.

      A boson is not a massless particle; it is a particle with integer spin [spin=intrinsic angular momentum.] Bosons can be massless or massive. Hydrogen atoms, for instance, are massive bosons. So are W particles. Photons happen to be massless bosons.

      You have the logic about the math backwards. The reason the mathematical formalism treats photons as massless gauge bosons is that *experimentally* they are massless, so we write down appropriate mathematics for that. W particles are massive gauge bosons, *experimentally*, and so we write down different mathematics for that, using the Higgs field along with a W field. Gauge invariance makes it much easier to write the mathematics down, so we use it as a principle in the equations. There’s no physics in gauge invariance; it’s a math issue.

      An important thing that makes gauge bosons (massive or massless) different from Higgs bosons is that gauge bosons have spin 1, and a polarization [which, for photons, is essential in polarized sunglasses] while Higgs bosons have spin 0 and do not. There are other differences: the possible interactions of gauge bosons with matter are much more restricted than are the interactions of Higgs bosons with matter.

  12. Matt: thanks for the answer, is pretty clear. I would say that in some way the Higgs field is not reacting to vacuum, that field expands along a space of positive gravity because is not an static realm. Perhaps the expansion creates a pull, so the particles that get in the field gather mass. I would say that a substantive dash of the Higgs particle shows a close interaction with the massive bosons. If in the origin the Higgs particle is a boson at the end seems a different object.

  13. What is the lowest mass-energy that the Higgs boson can have in accordance with the SM?

    What would the universe look like if the Higgs were to be lighter than the lower limit defined by SM?

    • This has a complicated answer, because there are many possible ways to ask the question.

      Suppose there is only one Higgs particle. Then theoretically the mass could have been very light, but that is no longer allowed by experiment. There is a model-independent bound from the LEP collider, which I think is 82 GeV, if memory serves. No matter how the Higgs decays, it must be heavier than that, or it would have been detected, at least indirectly.

      If you ignore experiment, there is a bound at very low masses, but I no longer remember what it is. It is again a bound that involves stability of the particular vacuum in which we live.

      If the Higgs decays exactly as predicted by the Standard Model, then from experiment the mass-energy has to be bigger than 115 (from LEP) and probably 122 (from LHC).

      If you assume that the Standard Model describes all physical processes all the way up to the energy scale where gravity becomes important (the “Planck scale”, about 1,000,000,000,000,000 times more energetic than an LHC collision), then you get a bound closer to 120-125 GeV; if it were lighter, the vacuum in which we live would be unstable and the universe would ended up looking very different. But you would be making a huge assumption, and quite probably a wrong one.

      If there is more than one Higgs particle, then there is far more flexibility. The lightest Higgs particle, if it is produced rarely enough at LEP and other colliders, can be as light as you want.

      I hope all those answers are correct… I might be mis-remembering something…

  14. Thank you for that.

    I read somewhere that all elementary “particles” occupy a spherical volume of the same dimensions, radius. The difference being in the energy densities profile, cross section. If this description was valid and given your description of a “jet”, the stretching of the proton (hadron), then would you agree that the fundamental mechanism that gives particles a distinct characteristic is one of geometry.

    I think another of phrasing this question, please correct me if I am wrong, is could bosons transition into fermions by interacting with each other. Then once a fermion it would take a finite amount of chaotic momentum transfer from other fermions and/or bosons to decay back to a boson?

  15. Matt Strassler said:

    “It is very easy for a professional to recognize an amateur: there’s far too much emphasis on the horse, and not enough on the cart; equations appear out of nowhere, without clear justification; the language is vague instead of being highly precise. In Einstein’s paper, there is not a single vague or ambiguous line.

    Your mistake — the classic mistake made by most people — is in thinking the theory is the horse. The theory is the cart. The horse is the insight, the idea. The idea and the insight make the theory possible. But an insight is not a physics theory.

    JFH^^: Any clear verbal statement or equation out of the norm made by someone that understands something that reverses a major concept or advances it that is not understood is vague to the observer hearing it. But even a vague statement based on proper insight over the problem the Great Professor spent the last years of his life on in turmoil and ridicule for refusing to throw common sense away and accept God played dice with the Universe with gravity disconnected in quantum mechanics would have been all he needed to see he was wearing his missing glasses just by making his head itch a little to scratch it. Especially if the answer was on a card with two opposite sides up his sleeve and it fell out scratching his head and he noticed the moment arm of force was at the bottom on one side.

    Professor, I see your cart sitting still named Atom carrying a book on “Time and Mass Oscillation” has two axels yet 3 wheels.” ‘Yes, that’s why I ride my horse named Sugar because it is the cause of the force that pulls the cart but the book is too heavy……humm.’

    “Your example of the equivalence principle is an interesting one. I think you need to read a lot more scientific history.”

    Three weeks before CERN’s shocking announcement last September neutrinos were braking the most fundamental law in Special Relativity amateur’s with the ability to see things differently playing “Foldit”, an online DNA game giving them a chance shocked the World and the scientific community by cracking the AIDS virus DNA code in only 3 weeks after the experts spent over a decade getting nowhere. So two “impossible” events happened right in a row.

    Then it happened again because immediately after CERN’s shocking announcement that neutrinos were exceeding the speed of light an amateur that had previously posted his findings on time and its relationship to Mass oscillation and phosphate and sugar phase timing spent 20 minutes doing the calculations that showed Stanford’s SLAC E158 data proved CERN’s neutrino data was correct and was caused by the asymmetry of the weak force and the neutrinos had not exceeded the speed of light confirming Einstein was right again. And it also showed Einstein made a mistake when he said he made a mistake….adding the asymmetry of the weak force and the harmonic comma the two sets of data combined produced creates a new cosmological constant. But politics remain the same.

    CERN’s neutrinos exceeding the speed of light @ v-c/c=2.48 sec in 453.6 miles is an exact match with Stanford’s SLAC E158 weak force asymmetry value showing the cause of 2.48e-5 is not the politics of a “loose fiber optic cable” checked countless times with the same “gain in space” shown by FERMI Lab’s neutrinos supporting an observation that goes back to 1947 and is summed up in 2007 by G. Nimtz and A. A. Stahlhofen who also thought it occurs outside the bounds of SR [arXiv:0708.0681v1] not aware of the simple explanation E158 data provides with direct proof provided by SLAC’s E158 data exposing a gain in 453.6 miles also @ 2.48e-5 with a .20 harmonic comma as I predicted for the needed asymmetry in the reverse arrow/phase of time the calculations reveal changing physics. SLAC’s data comes from the distance light travels in 1000 years at the speed of light in a ratio to a 1 hour SOL gain making this comparative measurement the most spectacular ever made in physics and does so in regard to the most important observation in the History of Man.

    What this means is E=m+{a}c2 outside the weak force where E=mc2 inside it because the original equation does not include the photon’s force carrier space the neutrino provides to exit the weak force to the strong force.

    But the Great Professor was right: there are no dice and {a} adds the cosmological constant needed to balance “H”. But remember we are dealing with concepts built out of time so you can’t have two sides of one concept at the same exact time. You can’t put up where down goes, or movement (velocity) with non-movement (position). But since you can’t have nothing (no Observer) without something (the Observer) to create the concept of nothing this logic creates an arrow to put a concept in an information frame whereas one side will tell you the other side. God plays cards to say “I Am” and slip us a new card in the middle of saying it.

    Low to high entropy, E=h+{a-lesser diesis}c/wavelength.
    High to low entropy, E=h+{a}c/wavelength. The lesser diesis is named Einstein’s comma, but here it’s Maxwell’s Demon and it cannot be in two places at the same time/size in ratio to time.

    John F. Hendry^^

    • I disagree. Many of Einstein’s papers were controversial — and widely rejected — when they were written. But they were not vague, not to other physicists. This is clear from the fact that certain (though by no means all) other physicists understood them immediately, even as they rejected them.

      In my career I have seen numerous breakthrough papers, nothing as big as Einstein but quite a few shockers. They were not vague. Confusing, yes; implausible, yes; vague, no.

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