Of Particular Significance

Some Higgs News NOW

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 02/07/2012

We’ve been expecting this: the ATLAS and CMS experiments at the Large Hadron Collider [LHC] are going to be making public shortly have made public the publishable form of their papers (preprints, which one submits to a journal for the purpose of peer review) on the search for the Standard Model Higgs particle (the simplest possible type of Higgs particle.)  These papers are based on the preliminary results that we heard about on December 13th, which I discussed in some detail here.    Here is a page where you can get all the ATLAS and CMS papers.

I’ll report after reading them.  There will probably be I see no major changes from December 13th, though there will be are interesting minor ones.  That’s because the measurements are very sensitive and precise.  [UPDATE 1: The two-photon measurement from CMS includes something new: they separate the small number of events that have two additional jets out from the rest. This subset of the data is sensitive to both the g g –> Higgs and q q –> q q Higgs production processes, and it shows an excess at 124 GeV/c2, consistent with the existence of a Standard Model-like Higgs at that mass.] [UPDATE 2: See below]

Since we last heard from ATLAS and CMS, the experimenters have been working to improve their techniques, with the result that energy and momentum measurements (which are crucial to estimating the mass of any potential Higgs particle, and have to be accurate to 0.5% to 1% for each observed photon, electron or muon) will have been adjusted slightly.  Since the results from the two experiments were slightly discrepant, favoring Higgs masses that differed at the 2% level (and each slightly disfavoring a Higgs particle at the mass favored by the other),  minor changes could potentially have notable effects on how consistent are the hints at the two experiments with each other. [ UPDATE 2: The updated results do not otherwise seem to reveal anything significantly changed from the Dec. 13th presentations; various numbers have drifted around by a fraction of a GeV in energy, but not enough to change notably the level of concordance or discordance between the two experiments.  ATLAS’s observed excess is still clearly higher in energy (about 126 GeV, and apparently a fraction of a GeV higher than in December) than is that of CMS (124, which doesn’t appear to have moved much), especially in the crucial two-photon channel — enough to raise issues about consistency, but not enough to make the results clearly inconsistent, given how little data is as yet available.  The statistical significances of the excesses have slightly changed, but by insignificant amounts. So… not much news that I can see so far, except for what I mentioned in UPDATE 1. Will report more if I learn something.]]

It is very easy (and psychologically tempting) to over-interpret small amounts of data, and we must fight that human tendency.  We simply need more data, about three or four times as much as we have now, and that’s what we’re hoping the LHC will get in 2012.

We can expect a little more news on the 2011 data set around the time of the Moriond conference (March) perhaps including more results from ATLAS and maybe a combination of the CMS and ATLAS results.  But new data?  Not before summer, and the large amount of data we’ll need for a much firmer conclusion probably won’t come before fall.  In the meanwhile, we’ll keep ourselves busy studying the many new results that will be coming from the searches for new and unexpected phenomena at ATLAS and CMS.

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35 Responses

  1. Matt thanks for this site. I have been having trouble keeping up since I retired.Your site gives me the details I have been looking for. I am still at ACP in the summers, see you there.

  2. Thanks so much for the helpful responses.

    Dr. Strassler, reading further into your site, I found that in physics:
    • “Elementary” when applied to fields and particles is merely a provisional term. Technological advances make composites out of former elementals. Both particles and fields ever reveal themselves to be composites.
    • Fields, such as the Higgs field or the electric field, are considered to be “just there.” They are not created by processes. So there is no physical mechanism to generate their criteria in the first place. The goal of particle physics research is to clarify the relationships between fields and their associated particles.

    So then, the fields themselves are actually *not* durable/rubust/permanent in nature, given that they are both composite and ever-fluctuating. Only the criteria/laws which describe the relationships between particles and fields are permanent—is that correct?

    From an interview with Dr. Amir Aczel (who I discovered via an entertaining interview with Dr. Brian Greene):
    “Most mathematicians I’ve talked to… are Platonic in their thinking which means that they believe mathematics is an existent that transcends the universe, it transcends the physical universe. … When I actually just talked to a pure mathematician over the weekend and I asked him a similar question. He said, “What do you mean? The universe just approximates mathematics. Mathematics is an existence that is much greater than anything physical.” Now having dealt with a lot of physicists since doing pure mathematics, I came to see that physicists don’t think that way. To them obviously the universe is number one and nature and what’s around us and mathematics is only a tool.”

    But if the physics itself is saying that there’s nothing durable/robust/permanent in nature, what then? Do physicists start talking about realities that transcend the physical?

    PS. Shamy, great heart-felt post, and I much appreciate what you say here: “matter alone never feel awe , matter alone never wonder , protons never care about their identity, electrons never seek meaning , but humans do because humans ARE the meaning of the cosmos.”
    I feel in agreement with the sensibility, but I think some aspects of the statement might block physicists from the meaning. I want to say something that sounds opposite to what you said, but I think that the underlying meaning is the same: Rather than viewing the universe as dead, believing that all meaning resides in humans, one can instead make an argument that the universe is, in a definable sense, “alive,” and that humans directly participate in that living reality (see “Nature Loves to Hide” by physicist Shimon Malin, and the review in the American Journal of Physics by Abner Shimony).

    Many have said that the missing element in the Standard Model 🙂 of scientific method is subjectivity itself—genuine clarity about the relationship between subject and object. Which does not appear easy to find. But I think that clarity is coming, don’t you?

    1. Dear Mark : Never forget my dear friend that being ” ALIVE” is not just a claim we can offer , being alive / being conscious is impossible without a living conscious agent , the transcendental higher realities of LIFE ITSELF , AND CONSCIOUSNESS ITSELF must be “” embodied”” in an agent who is able to think , to will , to wonder…..etc.
      Actually Life/Consciousness/Agent are a complete whole not a combined parts , so how can we consider the cosmos as alive ? is it a kind of panpsychism ?……my friend : let us only talk about primary , essential , fundamental FACTS , and there is only ONE , the human phenomenon , all other claims are just-so claims , i never accept just-so claims.
      The human phenomenon is the only phenomenon that IS , ie.; it has a kind of proof that is the ultimate , its premises ARE its conclusion without the need for logical link to reach C from P .
      So back to our main points , physics must be THE science of wonder , we must never allow equations and numbers to overwhelm our true nature , if we are as bodies part of nature , then we are as agents over and above nature.
      P.S.: Dear mark : I agree that math. is above matter , but the idea of platonic realm is pure theory or else where in that realm math.facts are inscribed?……math. have no meaning without a conscious agent , so it is the human again , ….my dear friend ; humans are a very transcendental/sophisticated/superior kind of a creature —ONLY IF HE ACTED TO TUNE HIMSELF TO BEAUTY, JUSTICE , TRUTH AND GOODNESS………THAT IS ;;; TO ATTRIBUTES OF GOD.

      That is the way i hope science expose the wonders of our world….the miracle of existence.
      TO MATT. :my great gratitude for your kind hospitality as a generous host to us your guests in your fine site.

  3. Somehow I happened upon this dialogue, and have the sense that I might clarify Dr. Shami’s question. Paraphrasing slightly, he said, “All fields can be specified, right? Are those specifications fixed or might any field have an infinite range of specs?”

    Dr. Strassler stated that “fields are what is.” And I believe that Dr. Shami is trying to clarify what the signified of “field” is, by asking about the limits of that signifier. If that signifier has an “infinite range of specs,” then, in what what way could it be said to be “essential” or “always there” as Dr. Strassler said? *What* is always there?

    Another way to ask this is, if a label is given to something — say I call it a guitar string — but tomorrow it looks different, so I call it a battleship, then, can I really say that the “guitar string” is durable/robust/permanent — i.e., “existed” in the first place?

    Not to beat a dead horse, but if field A is continuously morphing into field B, field Z, etc., with no underlying “fieldness” which acts as some kind of contraint in the variabiliity of the concept, then aren’t we in the same ballpark as with the particles — in that nature is demonstrating that “field” is not denoting something fundamental?

    If so, this suggests to me that while reality is certainly characterizable relatively (as particles, fields, puppy dogs, etc.), it is not characterizable ultimately (which is an ancient idea). This was where Dr. Shami’s line of questioning was leading, or so I thought. I’d love to hear if you have a response to this, and thank you so much for your kindness in offering your expertise to the public. I hope you are not so overwhelmed by questions that you have to give up the website!

    1. As far as current theory goes, a field is specified by several fixed numbers:

      Its “spin” (an intrinsic property of fields that determines whether its particles have intrinsic spin [electrons having the minimal unit of 1/2, photons having 1, and Higgs particles having 0.]

      Its “color-charge” (which is just a word describing how it is affected by the strong nuclear force)

      Its hypercharge and weak isospin charge (which determines its electric charge after the Higgs mechanism takes place; see http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-known-particles-if-the-higgs-field-were-zero/

      There may be other numbers that we don’t know about yet, for example some new kind of charge for which all known fields might be neutral.

      Some examples:
      *The gravitational field has spin 2 and no color-charge, hypercharge or weak isospin charge
      *The electromagnetic field has spin 1 and no color-charge, hypercharge or weak isospin charge
      *The electron-right field has spin 1/2, no color-charge, hypercharge -1 and no weak isosopin charge
      *The electron-left and electron-neutrino fields together have spin 1/2, no color charge, hypercharge -1/2, and are a doublet under weak isospin (where the fact that they are a “doublet” explains why the weak interactions can convert an electron to an electron-neutrino or vice versa, under appropriate circumstances.)
      *The up-quark-right field has spin 1/2, is a color triplet, has hypercharge 2/3 and has no weak isospin charge (where the fact that it is a “color triplet” tells you that it can be impacted by the strong nuclear force by interacting with gluons)
      *The Higgs field of the Standard Model (the simplest possible Higgs field) has spin 0, no color-charge, hypercharge 1/2 and is a weak isospin doublet.

      These quantities cannot be changed or affected by any physical processes.

      The fields of nature then also have fixed “interactions” with each other, and with themselves. The strengths of these interactions are specified by another set of fixed numbers, but it is not so easy to state what these numbers are, because each is affected by the others, through the complexities of quantum field theory. These numbers determine:

      * The strengths of all the forces.
      * The masses of all the known elementary particles (through the strength of the interactions between those particles’s fields and the Higgs field — with the exception of the Higgs particle itself).
      * The details of how, and how fast, these particles decay.

      Once you have specified the fields and the interactions among them, you have (in the current theoretical paradigm) specified the laws of quantum field theory and particle physics in a given type of universe. The process of particle physics research today is, for our own universe, about (a) measuring carefully the strengths of the interactions that we already know are there, (b) figuring out the specifics of the Higgs field, (c) determining if there are fields we may have overlooked or which may have been out of reach before current experiments, and (d) explaining why the numbers which specify the known fields and their interactions are what they are.

      1. Greetings for mark , i never mentioned that all laws , forces , constants , fields …..etc in our particular universe could be ” mutated ” to another values , my point is put simply : identity /essence/ ….ness are the set of all criteria which identify a thing, and as such all of what matt. mentioned are those criteria , but —a very big one indeed –the ultimate fundamental primary issue is not a physical mechanism to CHANGE the criteria , but a physical mechanism to GENERATE the criteria in the 1st place ,,,remember the big hype about superstrings that generates all of physics then it only generated nonsese they called 10^500 landscapes !!!! so my friends what i call specs./identity/essence , pick what you like IS AN INDETERMINED RIDDLE IN PRINCIPLE.
        we deal with what we observe then why some arrogant minds wants to deal with the unreachable.
        n.b.; read Dr. penrose (the road to reality) it confirms my point, but my point is logical necessity

      2. Its time now to state the crucial fact; all our dialogs are aspects of the true nature of the human mind , searching , asking , reflecting , feeling the transcendental awe in face of the awesome unknown , while matt. is concentrating on figures and numbers , graphs , etc , i look for the meaning , the wisdom , the purpose , ……we must never lose the site of the immense ocean for the site of the pond , my friend matt.: i respect to the highest degree what you and all scientists do , but for physicists in particular , never allow the human to mutate to a number crunching machine , see but numbers , hear but numbers , feel but nothing!!
        To be a human is to seek meaning and wisdom of the phenomenon , not to only search for the mechanism of the phenomenon .
        My dear friend matt. and all other friends who share this talk ; i am at least 20 years older than matt. and that give me the right to talk to him a sincere talk from the heart , never allow this precious site to be site of physical numbers only , extend it to be a site of feeling awe , wonder , astonishment , and to always search for the meaning………matter alone never feel awe , matter alone never wonder , protons never care about their identity, electrons never seek meaning , but humans do because humans ARE the meaning of the cosmos.
        Discard all fact free nonsense of the naturalism / materialism/ atheism self refuting nonsense, as if they are –as they insist–mere matter , then why should mere matter care about “”” struggling to prove its “” point of view”” can matter have a point of view??!!””

  4. p.s.:
    Dr. strassler was talking about empirical relative time-dependent reality
    I was talking about ultimate ontological veiled reality

    1. Is there anything that can be known about ultimate, ontological, veiled reality? The only thing science can do is tell you some things that cannot be true of that reality. But if there are multiple possible visions of that reality that are consistent with experiment, science cannot tell you which one is right.

  5. Thanks for your patience , let me re-state my question and it is my very last one ; all fields have some kind of specifications , right ? i ask : are those specs. fixed in one value or any field can have an infinite range of specs.?
    Thank you very much and it was great honor to have this dialog with you.
    best wishes
    aabed shami with respect

  6. Please note that i adopt the ontology of the great Dr. david bohm , and as such, particles do have essence and concrete existence in reality which for me makes much more sense………
    At the end no one can ever be sure of the exact nature of quantum reality, can we ?

    1. One can be quite sure what agrees with experiment and what does not.

      Bohm may have been famous and perhaps even great, but his ontology is not the only one available, and personally I am not impressed by it. Modern physics continues to press forward, and meanwhile Bohm’s ideas become increasingly obsolete… as he did not know many of the things we know and understand now.

  7. Some may say that my questions are silly or even foolish but any one upon reading Dr. despagnt great books ( on physics and philosophy ) and ( veiled reality ) will change their minds , existence is much much more wide , broad and high than any one can imagine. thanks
    shami with respect

    1. What is “must” here? What is “Fieldness”? You have to decide what your terms mean, and speak very carefully, if you want to ask philosophical questions of this type.

      Physicists, by and large, are not interested in whether fields have “fieldness”. “Fieldness” is a word that does not necessarily refer to anything real. Physicists are generally interested in what fields do and how they behave. We would certainly like to know if they are a consequence of something simpler or more profound or in some way more basic to nature. But that’s an experimental question [with theoretical undertones], not a philosophical question.

  8. Yes this is what i meant and thanks for your clarification , but then a more question “pops up” : are those fields a one obligatory value kind of existence or all fields have in principle an infinite spectrum of values/specifications , then what is the physical mechanism that assign to each field its specific value and specification ?
    N.B.: if you are tired of my questions or if i am wasting you time just tell me and i will stop , but what encourages me is your great clarification ability and sense of cooperation.
    thanks matt.

  9. That is great and fine , but please i need a specific answer for my question : is in reality all particles that can decay are essence-less ? i mean when the higgs decay to 2 photons then we lose the ontological essence of the parent higgs , am i right ?or the parent higgs have no essence and we are just dealing with ” blobs” of energy in different configurations ?are particles an existing “stuff” or what ?if an electron and positron are transformed to photons, where is the original electroness? it is the same as : where is the catness in the cat DNA!!!!
    I am not a physicist or biologist , i am mere structural analysis engineer with mere Ph.D in structural analysis.

    1. What is “essence”? What is “electronness”?

      Are you sure these things exist?

      I can tell you what electrons can do and do not do. I can tell you how often a Standard Model Higgs particle will decay to two photons. These are precise questions to which I can give you precise answers.

      But I cannot tell you if your current questions make sense. I am not sure “ontological essence” is something that can be lost, since I am not sure it has existence in the first place. And I am afraid, therefore, that before you will get your answer you will have to show that the notions on which your questions are based are meaningful.

      If what you mean to ask is whether there are aspects of the world that are durable, and robust, and permanent — if this is what you mean by “essence” in your questions — then what you are learning is that particles are not essential (do not have essence). The things that are essential (in the modern view of particle physics) are the fields of nature, on which the particles of nature are merely ripples. Particles come and go; the fields of nature are always there. Everywhere you go, at all times, there is an electromagnetic field, an electron field, an up quark field, a gravitational field, a gluon field, etc. These fields may just be sitting there, not doing anything. Or they might be doing something more interesting, rippling, for example, and those ripples you would identify as the presence of particles. But particles are not essential, in this sense of “essence”. Most of them decay; singly or in pairs they can be absorbed, destroyed, created, etc. Particles are like vibrations on a guitar string; the fields are like the string itself. The vibrations die away, but the string remains.

      I am not sure if this is what you meant, but I hope my answer is useful.

  10. Then an essential question is in place now : are building blocks of nature being in a state of decayable , transformable , interchangable flux an obligatory state implemented by some essential law of nature , or it could have been otherwise where all elementary particles are stable unchangable undecayable essences with rigid existence , if both states are possible then what mechanism would implement the former not the later ?
    This is a fundamental question of a very high importance.
    As you notice i concentrate on philosophy of ontology and would appreciate
    very much hearing the voice of an expert in physics.

    1. The question of what is and what might have been is one that scientists do study, though according to the rules of the framework in which we find ourselves. I cannot tell you why the world can be well-described as having quantum fields and their associated particles as its basic ingredients, with interactions among them that are local in spacetime. But if you grant me that this is the case, then I can tell you that the question of which particles are or are not stable is something that depends, in a completely calculable way, on exactly which particles there are, what masses they have, and how they interact with each other. If you give me a list of fields, their associated particles, their masses and their interactions with each other, I can calculate which types of particles will decay, how fast (on average), and to what (on average). [I’m simplifying slightly here; the calculation is always possible in principle, but whether I can do it in practice depends on how complicated the interactions are.]

      So for the particle physicist, your question is restated: why are interacting quantum fields the basic ingredients of the world?

      You should read my two articles about particle decay: http://profmattstrassler.com/articles-and-posts/particle-physics-basics/most-particles-decay-why/ and http://profmattstrassler.com/articles-and-posts/particle-physics-basics/most-particles-decay-yet-some-dont/

  11. Did you notice that the concept of particle is elusive ! as each particle is decayable into other ones then there is no particle essence per se , even the electron-positron pair are temporary! it will transform into photons , my aim in saying this is to clarify my point : the world of the micro is a flux not a permanent essence……….this is very amazing and puts energy as fundamental 5th. dimension on which the nature of nature depends…….there is no such thing as nature per se.

  12. sorry I do not mean the WIMPs of the dark matter , what i mean is : can a really unknown particles or fields affect what we observe ?you said we know the properties of the particles as per the standard model , well , but are these properties the fundamental ones or the apparent ones being affected by unknown particles/fields?the point is can we ever know if a property is fundamental or apparent meaning that observing from other perspective we would measure different properties, i mean from bird,s eye view not frog,s eye view.
    This is a very fundamental question.

    1. “WIMP” does not necessarily refer to dark matter.

      I think you are confusing two things.

      I am not saying that new particles might require us to entirely reevaluate the whole history of particle physics and every experiment that has ever been done.

      I am simply saying that new particles might affect particles we know in small ways, and particles we expect but do not yet know (in particular, the Higgs particle) in large ways, changing their behavior in experiments.

      You seem to be confusing the precise and detailed behavior of a particle (i.e., how does it decay) with some essential aspect of its being. The questions I am raising are not fundamental at all; they are practical. How will we recognize the Higgs particle when we see it, if it decays differently than expected? [Much like asking: how will I recognize the person I’ve been told to track down if he’s shaved off his beard? This is not a question about his essential nature but his surface appearance.]

  13. Dear Matt. : I understood from what you wrote that unknown WIMPs can affect the properties of the higgs particle , now let me extend this reasoning to the limit : Is it possible that WIMPs can in principle affect the properties of ALL particles not only the higgs so that what we observe is the properties of the massive particle-forces -fields network not the particles per se ?

    1. I think you’re over-interpreting because I didn’t explain clearly enough.

      First, WIMP’s are something specific, not what you describe: they are Weakly Interacting Massive Particles, particles that are affected by the weak nuclear force but not electromagnetism or the strong nuclear force. But the Higgs can be strongly affected by particles that are not affected even by the weak nuclear force.

      Second, by strongly affected, I just mean that it can decay in new ways, ones that could change its properties enormously. The other particles we know have been studied in great detail and we know a lot about their decays. New particles can’t change them very much; we already know what they are and what they do. That said, it *is* true that very rare decays to new and unknown particles could occur. For instance, a bottom quark could perhaps, very rarely (or we would know already), decay to a strange quark and some new undetectable particles — or to a strange quark and two lepton-antilepton pairs. Experimenters do look for these kinds of things.

      But there is no way for new particles to strongly change the properties of the bottom quark, which were extremely well-predicted by the Standard Model. The effect can be at most a subtle, tiny one.

  14. With an increase to 4TeV per beam at the start in late March, increasing luminosity, perhaps we will not have to wait for too long to hear something more concrete and exciting. Would 10 inverse femtobarns of collisions do the job ?? Let’s hope !.. The teams would certainly deserve it !

  15. 2012 will be a telling year. Anticipation is high, and as you say, the tendency to over-interpret a few suggestive results will be difficult to manage; as humans, extrapolation is in our nature, and when something is sought so rigorously, it is tempting to presuppose its success.

    That said, I am stymied to even imagine the concept that “energy and momentum measurements…have to be accurate to 0.5% to 1% for each observed photon, electron or muon.”

    Amazing. But faith in the effort provides belief that the folks and technology of the LHC and its collaborators can resolve this. And I for one, a simple fan, wish you and them the best of luck.

    If you happen to hear any interesting (real) comments to add to the “Top 10 Things Overheard at the Discovery of the Higgs Particle,” please feel free to add them here: http://wp.me/p1SONx-3t

    Best of luck,

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