Higgs Update

The Higgs discovery announcement will be at 9am next Wednesday. This is close enough that I can’t reasonably be accused of “subverting the scientific process” and ruining the LHC Higgs analyses by reporting the results here. Unfortunately, no source has provided me with these results yet, so that won’t happen anyway, at least not right now. However, I have learned the following, which may be of interest:

  • On Monday at 9am Fermilab will try and steal a little bit of the LHC’s thunder by announcing some new evidence for the Higgs from the Tevatron data. This uses the channel of a Higgs produced with a W or Z, the Higgs then decaying to pairs of b-quarks. This is a channel where the Tevatron is sensitive to a Higgs signal, but the LHC isn’t (at the higher LHC energies backgrounds are too large).
  • ATLAS and CMS each collected about 6 inverse femtobarns of data before the technical stop on June 18th, and they are rushing to get as much of it analyzed as possible. They are concentrating on the two most sensitive channels: H->gamma+gamma and H->ZZ->4l and are likely to have over 5 inverse femtobarns of 2012 8 TeV data analyzed in these two channels to present at ICHEP.
  • There may not be any 2012 Higgs data from other channels presented at ICHEP. ATLAS will have a H->WW->lvlv analysis, but likely not ready for public release.
  • To get the statistical significance necessary to claim a Higgs discovery, the experiments will be producing a combination of their best analysis of the 2011 data in all channels and the 2012 data in the H->gamma+gamma and H->ZZ->4l channels.
  • There will be no CERN combination of ATLAS and CMS results publicly released. This is not because such a thing is hard to do (and I believe it is actually being done, just not released), but because of political reasons. I don’t much understand these, but this blog entry gives some of the kind of reasoning being used.
  • With no CERN combination, attention will focus on Philip Gibbs at viXra log who in the past has produced reliable unofficial combinations of data, and is likely to do so again.
  • With the discovery a done deal, the attention of physicists will focus on the question of whether the signal being seen is compatible with SM predictions, or whether this new particle has unexpected properties. Here the main two numbers to look for are the ATLAS + CMS signal size in each of the two most sensitive channels. To get these, you can do your own combination of the separate ATLAS and CMS numbers, or wait for Philip. The signal size is a product of the Higgs production cross-section and the branching ratio for the channel. I’ve seen estimates of the reliability of the SM prediction of the cross-section varying from 15% to 25% (see more here). The branching ratios are much more accurately known.
  • Probably nothing new about SUSY at ICHEP. New SUSY analyses are being targeted for the SUSY2012 conference in August.

Update: Resonaances has more here, including the news that CMS will report 2012 data about the H->WW->lvlv channel (about the significance of this, see the June 29 posting at viXra log), and possibly others. Whether the 5 sigma significance level will be reached by a single experiment remains unclear…

Update: Finally confirmation from a reliable media outlet… The Daily Mail reports God particle is ‘found’. One evidence for this is that supposedly “Five leading theoretical physicists have been invited to the event on Wednesday”. This may mean Englert, Higgs, Guralnik, Kibble and Hagen, with Anderson getting dissed as usual.

Update: Tommaso Dorigo is providing background to the imminent Tevatron announcement here, and I assume will be discussing the actual results immediately upon release. The papers with the results will be released here this morning.

Update: The interesting bottom line from the Tevatron is that they see an excess in the bb channel that the LHC is not sensitive to, of size 2 +/- .7 times that predicted by the SM for a Higgs of mass 125 GeV. So, a marginally significant signal, of size consistent with the SM. The LHC should soon report the sizes of such signals in 3 other channels. In a couple of days we’ll have excesses in four channels, of sizes enough to claim discovery of a Higgs (or something very much like it, depending on how consistent the signal sizes are with the SM).

Update: The Tevatron paper on the Higgs combination is here. Most important number is the fit for the signal size for H->bb, for a 125 GeV Higgs. It’s 1.97 +.74/-.68 (where the SM prediction is 1).

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38 Responses to Higgs Update

  1. Michael says:

    Dear Peter,

    nice summary of current rumors, that might be in the right ballpark. The CERN seminar will be very revealing, for sure. Concerning the ATLAS+CMS attitude toward combining results, Aidan’s blog post has it right. It is very important that ATLAS and CMS establish independent evidence for a new particle of phenomenon and only combine once everyone is convinced that the discovery is real. There is a subtle but crucial distinction in the minds of experimental physicists when they know that their competitors might or might not confirm their results, and when they assume that they will and one will simply combine the results. Aidan and most collider physicists want to retain that distinction – and they are absolutely right in my opinion. Personally, I have no objection to Philip’s unofficial combinations. But I don’t agree with you that the reasons why ATLAS+CMS (not “CERN” by the way) are political.

    regards,
    Michael

  2. Peter Woit says:

    Thanks Michael,

    I see the argument about wanting independent discovery evidence. Still though, if neither experiment were to quite reach the discovery threshold, but the combination was well above it, few would take seriously official claims that the thing hadn’t yet really been found.

    As the question moves to whether the cross-sections for different channels agree with the SM, it’s going to be the combined values that people will look at. One could argue that providing the best combination is something ATLAS+CMS should be doing and not leaving up to Philip. In this case though, I guess anyone can add two numbers and divide by two….

  3. David Nataf says:

    Michael,

    You wrote:

    “There is a subtle but crucial distinction in the minds of experimental physicists when they know that their competitors might or might not confirm their results, and when they assume that they will and one will simply combine the results.”

    Would you care to elaborate?

  4. Michael says:

    Hi Peter,

    yes, for sure someone not on CMS and ATLAS very legitimately wants to see the combination. And an official combination will eventually be made. But first we need to see to what degree ATLAS and CMS agree, and that won’t happen in a serious way until the public announcement. This is why the combination comes some time after ICHEP (I honestly don’t know when). So there is no conflict between Philip’s unofficial combination and the unwillingness of ATLAS & CMS to make an official combination until well after ICHEP.

    Hi David,

    well, it is a question of wanting to avoid staking one’s reputation on a result that is later shown to be wrong. Think of the CDF di-jet anomaly, of muon bundles at D0, or of the OPERA anomaly for that matter. If you know you are measuring something that really exists, then you want to do the best possible measurement. That is challenging and stressful, for sure. But claiming to find new physics is the ultimate experience and no one wants to make a false claim and damage his/her career. So the emotions, mentality, fears and hopes are rather different when measuring something known and when claiming evidence for something new.

    regards,
    Michael

  5. OMF says:

    Two bucks says that the mainstream media makes an absolute hames of reporting the results and mass public confusion and ultimately annoyance ensues by Friday.

    It’s the uncertainty principle of science reporting: (Significance of Story) x (Accuracy of reporting) < (Average Twitter post)

  6. Peter Woit says:

    OMF,

    Actually I think the mainstream media has done a pretty good job on the Higgs, and will continue to do so next week. Part of this depends on CERN and the message they put out. In the interesting possible scenario of CMS and ATLAS independently having 4+ sigma but neither having quite 5 sigma significance, I hope CERN doesn’t try and add caveats, but sticks to claiming discovery.

    Many of the problems in the past with bad media coverage of physics have been the fault not of the media, but of the scientists themselves. In this case there won’t be lots of theorists running around making ridiculous claims about string theory, etc. All the media has to do here is figure out that they should ignore Gordy Kane.

  7. Owen Patterson says:

    Could the Large Hadron Collider Discover the Particle Underlying Both Mass and Cosmic Inflation?

    If the LHC discovers the Higgs boson or other theoretical particles, their existence could help explain inflation, one of the universe’s great mysteries

    Full article here:

    http://www.scientificamerican.com/article.cfm?id=could-lhc-discover-higgs-boson

  8. Peter Woit says:

    Owen Patterson,

    A good example of theorists making grandiose claims in the press guaranteed to cause confusion. If you’re a journalist reading this, no, the Higgs discovery will not tell us about inflation and the Big Bang. If you’re a commenter who wants to discuss cosmology, sorry, that’s off-topic.

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  10. Peter:

    This is an instance where your scepticism is misplaced. The Higgs field with a non-minimal coupling to gravity is a viable candidate for the inflaton, and in this case measuring the Higgs mass does tell us about inflation. (I am not commenting on the SUSY model also mentioned in the article, just a Standard model Higgs will do.)

  11. Peter Woit says:

    Syksy,

    As far as I can tell, the various versions of this proposal discussed in the SciAm article have all sorts of problems, and hardly anyone takes them seriously. Polluting a serious discussion of real physics with implausible speculation about some relationship to the big bang is something theorists insist on doing far too often. Getting a story like this in SciAm to coincide with the discovery announcement of the Higgs does nothing to encourage the public understanding of this science, quite the opposite.

  12. Peter:

    I think you’re straying a bit from your field of expertise! The original Higgs inflation model is taken seriously by the cosmology community (Wilczek, among others, has worked on it). I wouldn’t recommend the above popular article for learning about the model. It’s true that many people feel that the model has problems with ultraviolet completion and stability as an effective field theory, but there are no conclusive arguments.

  13. Peter Woit says:

    Syksy,

    My point is just that theorists would do well to take a vacation on July 4th from promoting their favorite speculative ideas for which there is no evidence (such as Higgs=inflaton). The public and press deserve a break from having theorists trying to confuse them about what is solid science and what isn’t. A headline about “source of the Big Bang discovered at CERN” is not what the field needs next week.

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  15. piscator says:

    Agree with Peter completely. There are a million half-baked models of inflation out there and they don’t become sensible just because a Nobel laureate worked on them. Next week is about results not speculation.

  16. gluino says:

    “I believe [the LHC combination] is actually being done, just not released”

    I sincerely hope not. The CMS collaboration was only shown the combination this week. Personally I’d be pretty unhappy if ATLAS gets to see our results before I do!

  17. kbot says:

    Hi Peter,

    The combination will eventually be done. The issue is that it requires the two collaborations to talk to each other to do the combination. The results are so new (putting all the latest data together) it won’t happen in time for ICHEP. Of course if the two collaborations shared data it could be done faster – but the point is that you want the analysis to remain independent until they are finalized. That is one of the whole points of having two experiments in the first place. If you share data and information before you are finished with the analysis it ruins the independent confirmation of two separate results…

  18. Peter Woit says:

    gluino and kbot,

    I may be wrong, but I was under the impression that the capability of doing a CMS/ATLAS combination was in place, just needing a limited amount of information from each experiment, and if one was willing to cut some minor corners, able to produce such a combination rather quickly. Philip Gibbs can do his version in a few hours if not less….

    Now, getting both experiments to sign off on the result, that I understand can be time-consuming.

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  20. Brian says:

    the Higgs is showing a small cross section into WW, which is quite puzzling.

  21. Christian says:

    Peter: Such a combination is, in fact, trivial if and only if one is willing to ‘cut corners’ as you say. These corners includes half-baked combinations of systematical error, which may be OK for Gibbs (I enjoy his page quite a bit), but certainly not OK for the ATLAS and CMS collaborations.

    Regarding the cosmology: As long as the Higgs-Inflation model cannot make eg. a solid prediction of m_H = 125 GeV, even Wilczek should take a day off and enjoy the show.

  22. The Daily Mail is being cited as a ‘reliable media outlet’?? You’re lucky they didn’t claim the Higgs boson causes and/or cures cancer…
    (evidence of their capability in this ridiculous article about scientific publishing: http://www.dailymail.co.uk/money/news/article-2160753/)

  23. Mithras says:

    Peter,

    I haven’t followed all of this for nearly as long as you have, but I was wondering about the “Anderson getting disssed as usual”. Could you explain?

    Also, I’ve made it through most of your book at this point, and have also finished The Infinity Puzzle, which you recommended. Is there another book or two you would recommend for those who wish to read about various aspects of particle physics?

    Thanks!

  24. Jim Martindale says:

    Mithras,

    On the right side of this web page there is a list of categories of links. Under the category “Categories” there is the category “Book Reviews”. They’re great. There are 26 reviews so far. I’ve read ‘Massive’ and ‘Shape of Inner Space’. Both are excellent, as is ‘Not Even Wrong’. Lee Smolin’s ‘The Trouble with Physics’ is also great.

  25. Dave says:

    Anderson first came up with an early version of what is now known as the Higgs mechanism. This was (I believe) a non-relativistic approach in the context of solid state physics.

    To leave him out of the festivities may well be unfair. Then again, he has been a vocal critic of particle physics so perhaps it makes sense not to invite the party pooper to the party.

  26. Peter Woit says:

    Mithras,

    About Anderson, see

    http://www.math.columbia.edu/~woit/wordpress/?p=3282

    For other books, an older favorite is Crease and Mann’s “The Second Creation”. As Jim Martindale points out, much better than consulting my memory is to get the full list of book reviews I’ve posted here the past few years, which includes all the recent books on this topic that I’ve read through and enjoyed.

  27. David Derbes says:

    Not that it matters, but I was a research student of Peter Higgs’s 1975-79. I have heard him speak about the history of his work more than once, and spoken with him about it many times. He invariably refers to about six or seven people, most especially Y. Nambu, G. Jona-Lasinio, J. Goldstone, P. Anderson and the other five guys recognized by the Sakurai Prize. (OK, that’s nine.) He’s a very modest person. For the longest time (and certainly for the four years I was in Edinburgh) he referred to “the well-known anonymous scalar” rather than a particle with his name on it.

    It might be worthwhile reading the relevant papers anew. As far as I understand them, the Guralnik-Hagen-Kibble paper talks about giving mass to a vector, but there is a disconnected zero mass boson still about. That’s not what seems to be going on in the data. To be blunt, there are a lot of people who deserve credit for the Higgs mechanism: the Sakurai Six, Phil Anderson and all the rest. But very frankly, the Higgs boson really seems to me to belong squarely to Peter Higgs. He may be embarrassed to have something named after him, but he deserves it.

  28. Anonymous says:

    @David Derbes

    Things may get very interesting after Wednesday. According to articles it looks like many of those names will be at CERN over the next couple days.

    Few points….

    Until the Physics World Interview below (from a few days back), I never heard Higgs mention GHK – seemingly demonstrating a good understanding of Nobel math. I have seen the “Life of a Boson” speech in video and text a few times (recently and well after Sakurai Prize).

    http://physicsworld.com/cws/article/indepth/2012/jun/28/peter-higgs-in-the-spotlight

    Guralnik compares the papers in the GHK history posted on arxiv…clearly his view.

    The History of the Guralnik, Hagen and Kibble development of the Theory of Spontaneous Symmetry Breaking and Gauge Particles

    http://arxiv.org/abs/0907.3466

    Additionally, the notion of zero mass boson in the GHK paper was posted on this blog in the comments section in the below link. Guralnik explains boson and how this differed from the Higgs paper (also inserted text directly from the above link).

    http://www.math.columbia.edu/~woit/wordpress/?p=4306

    The Beginnings of Spontaneous Symmetry Breaking in Particle Physics — Derived From My on the Spot “Intellectual Battlefield Impressions”
    Authors: G. S. Guralnik
    (Submitted on 11 Oct 2011)

    http://arxiv.org/abs/1110.2253

    p. 9

    Recently it has been claimed that the GHK paper does not have the “Higgs boson”. This claim astonishes us. We, far more than any of the other groups, keep very careful track of the degrees of freedom of our scalar electrodynamics model. On the bottom of the right column of page 586 of the GHK paper are the three equations for the leading order approximations to the 4 physical degrees of freedom. We observe that the two degrees of freedom of the vector field combine with one scalar boson to form the three degrees of freedom of a massive spin one vector field. There is one remaining scalar field, 2 in our notation, which in our approximation has zero mass. That this mass is zero has absolutely nothing to do with any dynamical constraint including the Goldstone theorem. The Goldstone theorem, if valid here, would only constrain the mass of 1. The zero mass is an artifact of how we pick the explicit action and the leading order approximation. This is different from the Higgs paper in that he puts in an explicit pure scalar interaction. In a 4 dimensional renormalizable theory that interaction is limited to being pure quartic. As was our practice mirroring that commonly used by Schwinger and associates, we did not put in this explicit quartic term in scalar electrodynamics but were fully aware that such a term is generated in higher approximations. Ultimately because, of renormalization, the GHK choice of the action is operationally identical to the one used by Higgs.

    In summary, our purpose was to show that the Goldstone theorem did not constrain physical mass in scalar gauge theories. We demonstrated this generally and in a specific example. The mass of 2 happens to be zero in leading order, but as was obvious to us and every other experienced field theorist of that time, this would change order by order as the theory was iterated in a manner closely related to how it changes in unbroken scalar electromagnetism.

    Hagen also spoke about this briefly in the Sakurai lectures.

    http://www.youtube.com/view_play_list?p=BDA16F52CA3C9B1D

  29. David Derbes says:

    @Anonymous:

    I have a friend who wrote a biography of Einstein (Walter Isaacson). A few years ago he was in Chicago because his daughter was looking at colleges, and my family and his family had dinner together. Aware of the “Nobel math” I asked Walter: Is the limit to 3 in the Nobel will? Said he: It is not. How did he know? “Because I’ve read the will.” Historically and by tradition they never give the Physics prize to more than 3. But it ain’t in the will, if Walter knew what he was talking about. I think the Sakurai folks did the right thing.

    To be honest, I don’t care personally if the Nobel folks wind up giving the prize to all of the living eight (R. Brout regrettably has died.) And I doubt Peter Higgs would care, either. He doesn’t need the money (he doesn’t care about money to tell the truth.)

    As it happens :-) I have the first GHK paper in front of me. The Nambu-Goldstone potential is not present at all. I quote: (bottom of page 586, PRL 13 (20) 16 November 1964): “While one sees by inspection that there is a massless particle in the theory, it is easily seen that it is completely decoupled from the other (massive) excitations, and has nothing to do with the Goldstone theorem.” It is also evident that their massive scalar has exactly the same mass as the vector. As far as I am aware, the to-be-announced scalar does not have the same mass as the W or Z.

    I reiterate: Many people, including but not limited to Peter Higgs, came up, I believe independently, with the mechanism (by whatever name you want to give it.) I heard Peter use many names in connection with the work, and if I work at it I suspect I can find the relevant talks in which, prior to 1980, he gives GHK full credit for their work. That said, in my opinion, the scalar to be revealed in 36 hours or so belongs to Peter Higgs (if the data support this.)

  30. David Nataf says:

    Isn’t Peter Higgs 98 years old? And he’s getting on a plane? wow !

  31. Peter Woit says:

    David,

    No, he’s 83 and doing fine as far as I know.

  32. David Nataf says:

    “98 years-old” was said in reference to Peter Higgs in a talk I went to, by someone very informed, but now in hindsight I think what was meant is that they shouldn’t wait the usual 15-20 years to award the Nobel prize, otherwise he’ll be 98 years-old when they give it out.

  33. Anonymous says:

    David Derbes

    You (and Walter) are smart and correct – it is not in the will (I knew that also). It is in the statutes.
    >>>>>>>>>>>>>>>>>>>>>>>
    http://www.nobelprize.org/nobel_organizations/nobelfoundation/statutes.html

    § 4.
    A prize amount may be equally divided between two works, each of which is considered to merit a prize. If a work that is being rewarded has been produced by two or three persons, the prize shall be awarded to them jointly. In no case may a prize amount be divided between more than three persons.
    >>>>>>>>>>>>>>>>>>>>>>>

    I don’t agree with you on the boson. It is clearly in GHK (but not stressed) and gains mass as it progresses in their model. They should have put in a sentence that stated and stressed “an essential feature of this theory is the boson” and it would have been more clear. :)

    Will be an interesting Press Conference to watch with all those folks there…Englert can say boson was “obvious” and GHK can try to explain the massless vs. massive and degrees of freedom.

  34. David Derbes says:

    @ Anonymous:

    Thanks for the clarification about the statutes, new information to me (and maybe also to Walter, who I will tell when I see him next.)

    I clearly have no idea what the Nobel committee will decide. I am sorry that these statutes are in play (I would have liked to have seen N. Cabibbo get part of the Nambu award, for example, and Dicke/Peebles and Gamow part of the Penzias-Wilson award.) I think the Sakurai folks got it right, and would be happy to see all six (including the late Brout) split it. But it ain’t up to us.

  35. Anonymous says:

    Pretty cool you know Walter Isaacson. I read his book 6 months back and thought it was great.

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  38. Anonyrat says:

    Humorist Andy Borowitz has already had an interview with Higgs (the boson).
    http://www.borowitzreport.com/2012/07/03/5-questions-for-the-higgs-boson-particle/

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