Of Particular Significance

Higgs Update Today: Inconclusive, As Expected

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 12/13/2011

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92 Responses

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  2. To add some reasons to think that Tommaso could be right, let me also add that Bill Murray polled 10 “leaders” of the ATLAS search: did you find the Higgs? 10 out of 10 said Yes. See the live chat at Nature:


    The other participant in the Nature live blog above was Gordon Kane. In another live chat where he participated, one organized by Science, he was so sure that he even overestimated the combined ATLAS+CMS significance level to be 5 sigma, well, it’s around 4 sigma, but the qualitative message is the same:


    Yes, Roser was skeptical and on the 1-10 scale, he said “I am a 1”, i.e. almost totally uncertain whether they found it. His being at the Tevatron could arguably be correlated with this downbeat message about the LHC. Still, I am convinced that most HEP physicists think that the likelihood that the signal near 125+-2 is real is way above 50% and closer to 100%. I don’t attribute importance to these polls but Matt’s sociological reports seem implausible to me.

    To join a theme of Tommaso, I must correct a mistake. I didn’t mean Gordy Kane. I meant the Victor Weisskopf Distinguished University Professor of Physics and Director Emeritus, MCTP Gordon Kane. 🙂

    BTW yes, it’s one of the first episodes when I think that the media’s response to the events was pretty much totally accurate. Maybe the PR folks at CERN have contributed to this outcome, too.

  3. Finally about the “media disaster” (sorry but somehow you stimulate me into spilling my guts here -on the other hand this is way better than writing a post on the matter). I think you will concur, having spoken with many experimentalists, that the media behaved quite a bit more soberly in this particular occasion than what was feared by most, CERN directorate included. I do not understand what do you gain by exaggerating matters in this respect. A media disaster is the one on the Opera result. But still, I will tell you I never bought into the whole issue of HEP being damaged by overexposition (crying Higgs, etcetera). So I disagree on that too.


  4. And let me add that you seem to me a little too obsessed with the titles, professor Strassler, and the pedigree of people who express valid opinions. I humbly suggest you to have a little more respect for scientists without checking the arxiv every second moment. I personally find that everybody has something to teach me, despite their background. Intelligence is required to be able to pick, of course.


  5. 100 ? 😉 My post got over 15000 hits. Plus those who read the Washington Post, etcetera…
    As for the limb: the ultimate word will be spoken next year. I remain of my opinion. While you continue to play with words, asking whether this is an observation (it obviously isn’t) instead of asking the real question, what would people bet on.

    As for your trigger strategies, sorry to tell you but the trigger table for 2012 running is pretty much fixed already. You are a theorist, don’t forget that.


    1. You are *so* transparent, Tommaso. Being on a limb now has nothing whatsoever as to whether it turns out there is a Higgs there or not. You made a 50-50 guess; you cannot take credit for being smart just because you turn out lucky.

    1. While you were busy finding Jack Gunion to provide a vote in your corner, I found (through scientific discussions) far more experimentalists and theorists in the “maybe it’s there, maybe it’s not” category, and stopped counting… I have more important things to do, such as thinking about 2012 Higgs-analysis trigger strategies.

      As for “theorists” — You must be joking, Tommaso. Do you think all theorists’ opinions on particle physics weigh the same? Lubos I know very well; he is an extraordinarily smart guy, but he has never written a particle physics paper in his life, and I go to him with string theory questions, not particle physics analysis. Peter I do not know, but I do know he also has not been doing particle physics for decades. Philip I do not know, but I don’t find any particle physics papers by him either. And finally: Jack Gunion is an excellent particle physicist with 40 years of experience, author of dozens of important papers, co-author of the Higgs Hunter’s Guide (a fundamental reference book on the subject), whose opinion on particle physics I respect highly, though I disagree with him in this case.

      Meanwhile, I have lost count of how many theorists I have spoken to here, of comparable quality and experience to Gunion, who politely disagree with him; and every theorist who said something similar to Gunion today in the CERN theory/experimental meeting was immediately put in his place by your experimental colleagues. You’re out on a limb, Tommaso, and there were 100 witnesses to that today.

  6. Ah, and Jack Gunion at cosmic variance calls the LHC findings “persuasive evidence”, thus agreeing with me (and disagreeing with you and the friends you interviewed).


  7. I think Matt is correct in being cautious. I think this is firm evidence that we would expect signal to increase in the 125 GeV bin by next year, and this result is good to begin culling incompatible theories, however we have to carefully separate statements in physics from the psychology.


    I too support the enthusiasm surrounding the Higgs evidence, and think people are entitled to their opinions, however the ultimate test is whether you would tell your boss if this is a sure thing.

  8. Ok. Case closed for me. But it is too much asking me to not only explain I am stating my own opinion if I do (which I do remark in the post today), but also to warn readers of what happened in the past fifty years to uncautious optimists about 3-sigma effects. It does not fly in a post -I would have to make the introduction longer than any body.

    Anyway, concerning your argument. I think the case for the W and the Z was far, far stronger than for a 40 GeV top quark or susy. Rubbia got carried away after the discovery of the vector bosons. I think that our (many of us) prior belief on the Higgs being there and being light and behaving as itself does count in what we personally believe about the LHC excesses. If you ask people for what they believe they will seldom tell you the truth. Perhaps I am wrong in being so candid to tell really what I think.


    1. Tommaso — I would have had no problem if you had titled your post: “Some preliminary evidence for the Higgs particle”, and in the article had said that your personal belief was that, because you think it likely that the Standard Model is correct, this signal is the real deal. But you made a super-strong claim in your title, complete with the word “Firm” and an exclamation point, and with no disclaimers — and that, I think, gives a very firm impression to the novice reader, of whom I am sure you have many thousands.

      One could reasonably argue that my own title could give the wrong impression (and Peter Woit did, I think) though I tend to think premature pessimism is generally less damaging to the reputation of the field than premature optimism… and it also garners far fewer hits.

  9. Gnart,
    Both ATLAS and CMS separate their photons by “quality” according to if they have converted in material in front of the calorimeter or not and also if they are in the barrel or end cap. The best resolution is barrel photons that are unconverted, where Fabiola quoted 1.4 GeV for ATLAS and Guido quoted 0.99 GeV for CMS. However, additional resolving power “may” be gained in CMS due to its very fine segmentation which becomes increasing more important at higher pile-up where most of the data were accumulated. Expect both ATLAS and CMS to understand the calorimeters better as time goes on. Recall the history of the ATLAS and CMS detectors which to 0th order cost the same: ATLAS’s money is in an expensive magnet (40%) and CMS’s money is 25% magnet allowing more for silicon and crystals.

    1. Thanks Jim… looking at the plots from the 2 talks, looks like the Higgs mass resolution is about 4.0 GeV FWHM for ATLAS, for a core sigma of 1.7 GeV. Then for CMS I see 3.5 GeV FWHM, giving a core sigma of 1.5 GeV.

      Interesting that for H>2 gamma, seems as though CMS has about 10% or so more background than ATLAS, but who knows, the CMS signal efficiency might be up by a factor that more than compensates.

      Seems to me like one would not go very wrong by just adding the histograms together…

      Then on the 4Lepton mode, interesting that ATLAS sees 71 events over their entire mass plot, and CMS sees 72 events. ATLAS expects 62+-9 bkgd and CMS 67+-6… again CMS has a bit more background, but might again have more signal efficiency.

      Kinda seems like combining the final histogram here would be more or less OK too.

      1. Actually there *is* a problem adding the histograms together… a serious one… with the photons. I don’t fully understand the issue yet but will update when I do.

      2. OK… naively I’d think one could divide by the efficiency function (assuming Higgs>2gamma) and then add the histograms. So the problems with adding the two histograms would arise if ATLAS and CMS had rather different efficiency functions. Given the similarity of the background between ATLAS and CMS, I’d guess the efficiencies are similar, but that is not really a conclusive test.

        Nevertheless, when a few thousand people are involved, they will tend to make it as complicated as they can due to sociological imperatives… sometimes a cigar is just a cigar though.

        1. The two experiments do not do the analysis the same way. You had better read the papers very carefully before you try to think of it as just about an overall efficiency.

          The reason they make it complicated is to get the maximum sensitivity to the signal. For instance, photons that travel unaffected through the tracker must be treated differently from photons that convert to an e+e- pair as they pass through the tracker, because the mass resolution that you can obtain from the two types of photons is not the same — so if you combine them all together, instead of analyzing them in separate categories, you get a worse mass resolution overall, and end up with less sensitivity. Similarly, photons in central regions of the detectors are better those in than the end regions. The complexity is not about sociology; it is about trying to improve the measurement. You underestimate how smart these people are.

      3. Good point Matt. For H>gg, looks like ATLAS has 9 subsamples and CMS has 4, and they make limits for each subsample and then combine. The heteroschedasticity and variety of background levels supports they way they did it.

        It would be interesting to know whether any particular subsample is providing an unexpected portion of the `hint’, and if that subsample is expected to be more sensitive one (or less sensitive one). ATLAS does look a little odd IMO on this point. But the collaborations would have to `do it right’.

        Both collaborations did combine all 9(ATLAS)/4(CMS) subsamples in one grand histogram per collaboration, though…. so they diluted their own apparent sensitivity in a way, but I guess just for PR.

  10. Hi Matt,

    did you cross your mind for a second the fact that different questions create different answers ? If you ask your colleagues “do you believe the results constitute an observation of the Higgs” you might get a different answer than if you ask “what do you really believe about the Higgs being or not being in the 123-127 GeV range, after seeing the LHC results ?”…

    In any case, I do not think it is so strange if many are shy about being all in for the Higgs being there. This is common in HEP. I myself have shrugged my shoulders a hundred times at tentative signals in my blog, and have invariably been right. Now for once I am a believer, and I get attacked. Fine, but you are wrong when you say I should first warn about UA1’s top quark and the dozen other failed discoveries. I do that day in and day out in my blog, and of that you cannot accuse me – there is tons of evidence in the 2000 posts I have written in the last seven years.

    I think I am entitled to an opinion -and I would venture to say an informed one, since I sincerely know more than you about the details of at least one half of the story- even if it disagrees with that of a lot of my (more shy, I’d guess) colleagues.


    1. Tommaso (I *will* learn to spell your name; apologies for the repeated misspellings) — I’m not doing a “poll”, so the question isn’t uniform … but I never heard words like “firm” or “strong” from anyone I spoke to. I heard a lot of cautious remarks in detailed scientific conversations, both vaguely public and private, with first-ranked scientists in your experiment and in ATLAS… people you know very well. [I am sorry, I do not feel I can reveal names since these were scientific discussions and I did not ask the individuals if I could say anything about their personal opinions in public.]

      And it’s the Higgs we’re talking about! You *know* that anything you write about it is going to be read by lots of reporters and the public — and most of those people are *not* reading your other posts with the caveats about all the non-discoveries. Don’t you think you should have a disclaimer somewhere on *today’s* post, not just on other posts that so many people will never read, pointing out how often freaky things happen in real data?

      Methodologically: Personally I feel you have mixed theoretical bias about the Standard Model being correct in with experimental data, in a Bayesian fashion that I don’t agree with methodologically. And theoretical bias is a road to hell for experimentalists; you know that. That’s how Rubbia found the top quark and supersymmetry in 1984; he thought they should be there. Sometimes it turns out, by luck, to be a road to heaven, when he found the W and Z particles, which were indeed there. Which road are we on now? And should we tell the public that heaven is in sight at this point, when we really do not yet know?

      p.s. re: earlier; I am keeping my $100 for better uses; I bet when I know I will win. Here I do not know what is going on.

  11. The strength of the low mass analysis lies with the excellent mass resolution in 4l and gg, together with the absolute calibration at the Z. The single biggest piece of evidence that was shown today was the ATLAS gg mass plot, where one can conclude that it has an interesting feature at 126 GeV. If that was all the information that we had, I would definitely call it evidence for the higgs. BUT, CMS does not see an enhancement at that mass with an arguably better electromagnetic calorimeter. So therefore, the evidence which we would have from ATLAS alone is greatly diminished. That CMS sees a low mass enhancement does not strengthen the overall higgs evidence.

    1. Jim how does the resolution on m_gammagamma compare between CMS and Atlas near 125 GeV?

      It is a lot of fun that the Higgs mass region of great interest to theorists is by coincidence the spot where experimental sensitivity is worst. Gives this whole thing a nice `cliffhanger’ plot!

      Thanks Matt… on combining the data… of course you are right. But 4lepton and gamma gamma probably are relatively insensitive to the cuts. Not perfectly, but those are fairly simple final states.

      *Except* one thing… in the old days signal could be enhanced relative to background by demanding similar energies in the final state particles… for H>gamma gamma, asking that in the lab E_gamma_1=E_gamma_2 tended to enhance sensitivity, because background tends to come from one hard gamma combining with a soft gamma (the latter are plentiful) 4lepton might have something similar. With the 4leptons fakes are probably not much of an issue, though, although the background might be kinematically different than the signal. I’ll have to check through the talks.

      1. Let’s double check the cuts. I believe that the in four-leptons, one has to push the momentum of the allowed leptons down very far, and ATLAS and CMS do it differently. I think this is part of why ATLAS has far fewer events overall than CMS at low mass. But don’t quote me yet; I haven’t had time to verify this.

  12. Matt… thanks for emphasizing the look-elsewhere effect, which is likely the reason that 3 sigma or 4 sigma bumps (estimated without the l.e.e.) vanished in the past.

    It would be very useful if the simple H>gg and Z-4l *histograms* (not limit plots) were combined. With DataThief and all the interest, perhaps this has happened already. A bit unfair because cuts are different, but nonetheless, I suspect the feature near 126 GeV in Atlas melts a bit when combined with CMS at the raw histogram level.

  13. Matt,
    let me add to Peter´s words that even if Tommaso were contradicting Heuer this is in no way a problem. The recommendation members of a collaboration get after a result is publicly announced is that they can interpret the result they way they believe is the correct one provided they make absolutely clear (which Tommaso does) they are not speaking in the name of the collaboration. It would be nonsense to to put an embargo on the very people who are most qualified to talk about this result just because they can´t all agree. So besides making an incorrect statement (the one in which you are basically claiming Tommaso believes the Higgs was discovered), you are implying (again incorrectly) the fact that he is breaking rules that he is in no way breaking, something you would know yourself if you were member of CMS or ATLAS.

    1. I cannot contradict what you say, except for the fact that I did not and do not claim Tommaso says he believes the Higgs was discovered. I disagree with him that the evidence is firm. If this counts as “firm”, we shall have to redefine the word.

  14. Matt,

    First of all, I don’t see the contradiction between Tommaso referring to a 3 sigma effect as “firm evidence” and the DG preferring to be use the non-technical and highly cautious formulation “tantalising hints”. And even if they were in contradiction, as far as I know having a contradictory opinion to that of the DG is not only allowed among the 6000 or so physicists involved, but not even uncommon…

    By the way, have you taken a look at the plots Philip Gibbs has put together?

    1. I’m spending my time talking to experimentalists and trying to understand exactly what they did and what their opinions are. I have yet to talk to a single person who shares Dorigo’s opinion — not one, out of about 20 experimentalists, all of them faculty, and from both ATLAS and CMS.

      1. Ok — Peter, sorry to have been a bit short earlier — there was a heck of a lot going on simultaneously and I wrote fast answers which may have come across as dismissive.

        When you make naive combinations, you get naive results. Among my friends and colleagues are those who actually do the combinations. I see what Philip Gibbs is doing and my reaction is to nod respectfully and move on — the part that I trust that he can do, I can also do more or less by eye, and the part I cannot do by eye, I do not trust that he can do without knowledge that he cannot have — it requires the data and the systematic errors. (That’s why would it takes the experiments so long to do combinations!)

        One reason I am not happy with what Dorigo is doing is that he fails, while claiming “firm evidence”, to remind the public of the top quark at 40 GeV, the pentaquarks, the monopole, supersymmetry in monojets, the oops-Leon, the 17 keV neutrino, the split a_2, the supermillisecond pulsar, the January 2011 Higgs-to-2 photons peak, and on and on and on — there are more mistakes and flukes than discoveries in science, and it would be wise for us — and for the public — to remember that. I remember history and take a step back; Dorigo wants to be part of history and takes a step forward.

        Dorigo is very smart; but so are his colleagues. When you have very smart people disagreeing over whether there is firm evidence or not, then the evidence is not “firm”, essentially by definition. So for him to use the term “firm” without pointing out how many of his colleagues disagree (it may not be the huge fraction that I happened to find, but it is probably of order half) is implicitly misleading.

      2. Hi Matt, I’m having a little trouble with your “reply” feature, this is supposed to be a “reply” to your second “reply”, which I appreciate.

        I don’t see much point in arguing about which words to use to describe things, when there’s no substantive disagreement about the science. Whether people choose to express themselves in cautious or enthusiastic language is a personal choice, and I don’t seen anything wrong with Tommaso’s particular choices here. No one seems to really disagree that these results are quite compatible with what one would expect if a 125 GeV Higgs is there, much less compatible with the no Higgs hypothesis. Yes, one will have to wait for next year to be sure a Higgs (or something like it…) is there, but this is a pretty dramatic moment, moving the story from “we’re just seeing noise” to “we’re seeing something that looks like a Higgs, not noise”. Personally a few weeks ago I was looking at the latest data available and feeling hopeful that the LHC would produce the unlikely result of excluding the Higgs, because that would be very weird and hard to understand, but tremendously exciting. Looking at this data I pretty much give on that hope. This is very serious new information about the world.

        What Philips Gibbs is doing has its limitations, and can’t be taken too seriously, but it does a good job of doing what one tries to do approximately by eye, putting together the different pieces of information available. For example, I’d like to see a reasonable first hack at putting the gamma-gamma data from both experiments together. I can try and do that by eye, but it’s not so easy. His plot validates what my eyes were seeing: a bunch of independent consistent pieces of information pointing to a Higgs. Any one of them could be dismissed, but the total picture is now heavily weighted towards the Higgs hypothesis.

        Sure, this kind of 3 sigma-ish result may be a fluke and go away, but most of the examples you give aren’t very comparable. An incredibly large amount of careful work has gone into this one and there’s a lot of independent pieces all pointing in the same direction. Again, I don’t see anything wrong with describing this situation a bit incautiously. It’s a very dramatic moment.

        1. Peter — You are an ex-theorist, I am a theorist; in the end I defer to the experimentalists to determine how much I should trust what they’ve got. Tommaso and one commenter are still the only ones I have spoken to who are making a positive case. Not that the others I talk to say the case is terrible — no one says that either — they just say it seems still very inconclusive. They are reasonably optimistic that it might be the Higgs, and reasonably pessimistic that it might not be. You are far more optimistic than they are. I am curious: did you ever, as a student, get a chance to analyze real data from a particle collider?

      3. Matt,
        I was working on a collider experiment at SLAC (the Crystal Ball at SPEAR) about the time I’d guess you were doing elementary or junior high school science projects. From that time on I’ve spent most of my life thinking and learning about particle physics and related mathematics, getting a Ph.D from Princeton in the subject. If you start with a Ph.D. in a subject and keep trying to learn more about it for nearly 30 years, you end up knowing a thing or two. I’m still learning, about a lot of things, from the mathematics of quantum field theory to the details of what people are doing at the LHC.

        As far as experimental particle physics goes I’m well aware that the small amount of experience I had working in that area is irrelevant to understanding what is happening at the LHC. The scale is completely different and the difficulties are orders of magnitude larger. One thing I’ve learned over the years is knowing the difference between what I understand and what I don’t. I do understand quite well exactly what the scientific claims are that are being made in the ATLAS + CMS papers. What results you may get from a badly worded oral poll just aren’t either very interesting or very relevant.

        1. Last point first: it wasn’t even a poll, much less badly worded (I did not ask people the same question, and in fact I usually didn’t ask anything — we just got to talking, often about details of the results.) So it was ultra-unscientific, and I don’t claim anything other than an overwhelming disagreement with the position Dorigo took. But go ahead and ask around yourself; you don’t need to take my word for it. I’m sure you have many good friends among the LHC experiments whom you can ask for an honest opinion.

          Your experience at SPEAR is good to know about. As a graduate student I myself worked briefly with Jonathan Dorfan on data from PEP, and stayed in close touch with experimentalists throughout graduate school during the SLC era. As you say, even though the data from an e+e- collider is also a mess when you first get it, it doesn’t compare to what one deals with in hadronic collisions. The shift from e+e- physics to hadron physics around 2000-2005 [partly while still doing string theory so I could actually get a permanent job] was the most difficult and longest transition I ever made (and as you know I have worked on many different things.) In particular, what I learned in the process was how crucial it is to understand as many elements of an analysis as possible that never make it into the papers, or even the talks. This is essential both in my own position and of course in Dorigo’s (he always knows things about CMS that the rest of us don’t know, which is why normally I trust his judgment — for instance, I learned from his stated point of view that the hints at 143 GeV were not holding up in the late summer’s data — but not this time, since I know a lot of people in CMS who disagree with him.)

  15. Matt,

    Actually, I think your headline is more misleading to the public than Tommaso’s. “Inconclusive” is a non-technical term, easily interpreted by the public as “no progress, learned nothing”, as in, a medical test was “inconclusive”. Tommaso’s “firm evidence” uses standard usage in this field of “evidence”=3 sigma. To me, he’s saying this is a 3 sigma effect, and a solid one, with the 3 sigma not due to finagling. I suspect he can make a strong case for that: he’s a member of the CMS statistic committee, well aware of the ins and outs of issues like the “look-elsewhere effect” (which is not relevant here in any simple way, since what is making people sit up and take notice is that both experiments are seeing something around the same mass value).

    The details of what CMS/ATLAS have seen are clear and well-explained in Tommaso’s posting, and the bottom line is that what is being seen is reasonably consistent with a 125 GeV Higgs hypothesis, seriously inconsistent with the no Higgs hypothesis. You can describe this situation to taste as glass half-empty (“inconclusive”, since it’s not yet 5 sigma one way or the other) or glass half-full (“firm evidence” against the no-Higgs hypothesis, in favor of the Higgs hypothesis), but going on about a “serious error”, “crossed a line”, and “I cannot imagine how much hot water he is in now” is uncalled-for.

  16. The key weakness of the evidence, as you elude to, is that nothing lines up, in the high-resolution channels, not the CMS ZZ* and gamma-gamma, nor CMS and ATLAS. The main result seems to be understated, that a big chuck of mass space for SM higgs is ruled out. Also overlooked is the high mass region (> 600 GeV) being wide open. I personally would bet there is TeV (or multi Tev) physics lurking whether or not the higgs exists.
    I was at CERN in 1983. Physics at the energy frontier was most definitely NOT more peaceful then. It was “dog eat dog.” Now it is actually very peaceful. Ever since the era of PETRA, physics of competing experiments has been homogenized.

    1. Jim — thank you for your point about CERN in 1983. It was probably more peaceful externally but more vicious internally…?

      I agree that the new exclusions are certainly big news (see the next post I put up).

      As for lining up — intelligent people made arguments to me, after the talk, that they may line up better than it looks at first… that we cannot draw a strong conclusion yet. There could be a fluctuation in background that moves the best-fit two-photon mass peak up or down by a GeV. There could be some small issues with energy calibration that could move things up or down by 1/2 a GeV, perhaps.

  17. Do not forget D0/CDF data. They are on the track for a new article…The last D0 update is from November!!!

    So, if ATLAS, CDF, D0, and CDF all together do not exclude 120-127 GeV region, we have most probably a BINGO

    1. Well, BINGO, or there are two Higgs particles, each harder to produce than Standard Model particle, or there is one Higgs particle with a reduced production rate, or there is one Higgs particle with a reduced decay rate to two photons, or …

      But thanks for pointing out that there will be an improvement from Tevatron’s last data.

  18. If these hints prove to be the first evidence of an SM Higgs, what precision is expected in the ultimate measure of its mass by the LHC? Do we know based on the equipment or statistical tools? Is it in the ballpark of the experimentally determined accuracy we have for the weak bosons? (apparently 1 part in 5000 or so) If we’re heading towards even a fraction of that kind of accuracy for the SM Higgs, to a layperson a series of hints spread over a 2 GeV or greater range raises a brow, perhaps not so much if the methods are only expected to yield say +\- 1 GeV. I imagine the sigma-‘nificance’ values take such things into account but I haven’t seen it mentioned directly.

    1. It will be much better than 1 GeV eventually, I recall; but how much better? you’ll have to ask the experts; this is really dependent upon tricks that the experiments might learn to play with large amounts of data — and it also depends on exactly what the Higgs mass is, and how Standard Model-like it is or isn’t. If any experimenters want to chime in, please do, but probably most of them are unwilling to predict just how well they may eventually do.

    1. Ok, Michael (professor Michael Schmitt, Northwestern University) thank you for adding another vote! Don’t know why the votes are so skewed here at CERN, but it has been one after another… all very serious senior people with decades of experience.

  19. You are being unfair with Tommaso. I suggest you to read his blog entry because if you ask him the same question, the same way you did for others “how many say that the evidence presented today convinces them that the Higgs has been found?”, the answer would be “no”. The key difference is the statement “has been found” which is to mean discovery. Tommaso merely says his personal opinion is that what was shown today constitute EVIDENCE that it might be there, even if this is not your opinion. I´m sorry your statistic poll is so low but if you had asked a bit more around you would know this is the opinion of MANY people in both ATLAS and CMS, that are of course not convinced we found the Higgs, but agree the evidence is very intriguing. I give you that “firm evidence” might have been too strong but not as strong as you are suggesting.

    1. I agree the word “firm” is the serious error. If he had said “some preliminary evidence” he would have gotten away with it. As it is, it seems to me that he has crossed a line, and created a media storm all on his own.

      1. Your statement is not so scientific as I wish to be. I can reverse the questions like:

        a) do CMS, ATLAS, D0, and CDF excluded high-mass SM Higgs? Yes or No? The answers is already Yes…even with 8 fb^-1
        b) do CMS, ATLAS, D0, and CDF exclude 120-127 GeV region? Yes or no? The current answer is No…

        It seems that 120-127 GeV can’t be excluded so easy, as it is the case of high-mass Higgs, right?

        I can wait 🙂

        1. See answer below. If you can’t exclude 120-127, that may be because you had a bad fluctuation and the Higgs is harder to find that you think, or because the Higgs is there. How do we decide?

          But the good news is that all will be revealed in 2012, if the LHC operates as we hope it will.

      2. I don’t have the illusion that we are going to find Higgs for one year. However, I follow all Fermilab and CERN peer-review articles, and all data point into low-mass Higgs. And we know that Tevatron and LHC use different collisions and different cross sections. So, despite the messy data, fluctuations, etc. I think, here is the “art”, to extract the big picture out of the fluctuations. We will never remove the fluctuations…
        I agree, we still don’t what causes this “convergence” of the Fermilab and CERN data towards low-mass Higgs. We need more data to draw the big picture better, and I’m ready to wait the new pp runs, as well as more often participation of the Fermilab guys.

      1. Hey Matt. Regarding the straw poll of physicists. It depends completely how you phrase the question. Of course they aren’t convinced that its the Higgs (or something like the HIggs) going by the data thats available. Its obvious that no sane physicist can make that judgement yet. But if you ask instead, what is your subjective bayesian prior that this excess will go away after more data is taken, I think the immense majority will give a very low probability. Fair?

        1. No, not fair at all; I don’t think so. Most experimentalists I am talking to start to answer me by telling me a story about a 3 sigma result they know about that went away after more data was collected.

          Explain to me, please, how it could be, statistically, that the four ZZ events at CDF reported this summer at 325-327 GeV were a fluke. And yet it appears they were.

          Certainly this *might* be the first hint of the Higgs particle. And certainly it might not. I would put the odds somewhat worse than 50-50 — which is still pretty good odds! I certainly am not going to bet you $100 dollars that it is not there.

  20. Hi Matt,
    Thanks for the excellent summaries. I watched the webcast and came away with same impression. I understand that the CMS people would have preferred another month to go through their data analysis before going public. In any case it is great that there are some hints — lots to look forward to in the coming year!

  21. Thanks for the analysis Matt! Greetings from 5am on the West coast, the webcast was so jerky that the sound was incomprehensible but we could at least see the plots…

  22. Hi Matt,

    I’m watching anxiously and hoping for your three-sentence conclusion. What do we know today that we didn’t know yesterday? I have a collection of 24 museum educators who will want to know in about two hours. Three sentences is about the most they can handle.

    1. Sorry I didn’t get to this. We know the Standard Model Higgs is not above 128 or so GeV in mass. We don’t know what’s going on around 125 GeV but it is possible there is a Standard Model Higgs there.

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A decay of a Higgs boson, as reconstructed by the CMS experiment at the LHC


The idea that a field could be responsible for the masses of particles (specifically the masses of photon-like [“spin-one”] particles) was proposed in several papers

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 04/16/2024

Although I’ve been slowly revising the Higgs FAQ 2.0, this seemed an appropriate time to bring the Higgs FAQ on this website fully into the

POSTED BY Matt Strassler

POSTED BY Matt Strassler

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