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    Excess ? What Excess ? ATLAS Clarifies.
    By Tommaso Dorigo | May 8th 2011 03:06 PM | 25 comments | Print | E-mail | Track Comments
    About Tommaso

    I am an experimental particle physicist working with the CMS experiment at CERN. In my spare time I play chess, abuse the piano, and aim my dobson...

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    In a display of nonchalance that should teach us a thing or two, the ATLAS collaboration has put an end to the Easter Higgs Rumour (EHR), which brought the blogosphere in an excited state for at least a week, and experimentalists and theorists for even more time. They did so by publishing a very narrow-focused document, totaling less than five pages, where they discuss the backgrounds to Higgs boson decays in the diphoton final state.

    In the paper they do not seem to mention the EHR at all. It is just as if they were working at all these nice analyses they are doing, and at one point they said, "Hey, why don't we put out a background study for Higgs searches in diphotons  today ?" "Yeah, that'd be fun, let's do it" .

    This strikes me as a bit odd -it looks like acting in denial, pretending, that is, that there was no leak, that nobody discussed their internal matters. Odd to the point that if it was a single person doing this we might dub as childish such behaviour. The thing is, wee may like the web or not (I love it), but we certainly cannot ignore its existence, lest we look like aliens. While a blog or two may be happily ignored by 3000-strong collaborations without anybody finding the thing weird in the slightest, the situation changes if the rumour of an internal 4-sigma signal by the experiment reaches the media around the world.

    Anyway, let me comment briefly the information that ATLAS decided to publish. The document focuses on 2010 and 2011 data and describes the background sources to events with two photon candidates of high momentum. To the 38 inverse picobarns of good 2010 data, 94/pb are added for this study -thus almost doubling the statistics on which the EHR was originally based. Surely, if half the data showed a 4-sigma signal, one expects to see a Empire State Building-sized peak in the whole data, right ?

    ... Right. Unfortunately, that is not the case, but what's somewhat surprising is that the former peak at 115 GeV, obviously a fluctuation, is not just dampened by the added data, but actually it becomes a deficit!

    Now, I cannot comment on that internal document of ATLAS -I am no New Scientist reporter- but what I can certainly say is that the data on which that alleged signal was based had been in large part already published by ATLAS, since it had been in a talk at the Moriond 2011 conference just a month before. And the Moriond plot did show some upward fluctuation at 115 GeV, although one completely in agreement with estimated backgrounds.

    The added data have made the upward fluke a downward deficit. You can check it out in the figure below, or see the two twin figures in the paper. What is interesting is that ATLAS shows the 2011 data alone, as well as the 2011 data together with the 2010 data, but they do not show the bumpy 2010 data by themselves.


    In maybe the only point where the ATLAS document seems to address the EHR, they clarify that a Higgs boson of 115 GeV would contribute to two adjoining bins in this distribution, given the known resolution on the diphoton invariant mass and a Higgs boson produced by standard means (that's a necessary specification to make, since a Higgs produced with large momentum by some exotic mechanism would give higher-energy photons and thus a different expected width of the reconstructed mass; but of course the events in this plot do not have the two photons with large boost).

    In the end, what should we conclude from the ATLAS paper ? Nothing more than we already had -there is no 30-times-enhanced Higgs-like particle decaying to photon pairs in LHC data. Sorry, folks -the road to a deepening of our understanding of matter at the fundamental scale is still long and unfortunately bumpy -bumpy with the wrong kind of bumps, unfortunately.

    UPDATE: on the matter Peter makes the same point I made above, in the very title of his post on the matter.

    Lubos also discusses it shortly in his blog.

    Philip Gibbs had also written a piece on the new ATLAS report, which I unfortunately overlooked. See here.

    Comments

    "The thing is, wee may like the web or not (I love it), but we certainly cannot ignore its existence, lest we look like aliens."

    Imho they definitely took the web into account by preparing this very publication. Should they openly comment on a non-approved internal memo by four persons? I think that no.
    Hopefully just another minimal thrill that will be wiped out by the future discoveries... I agree that Atlas' cool should teach many of us a thing or two...

    >childish such behaviour

    Not so. Aloof, and lofty rather.

    "Here is a paper that we prepared earlier. I heard some noise last week on the Interwebs, what was it about again?"

    It's too bad internal notes can't be widely distributed to the general public or people with interest (other scientist) without media misinterpreting the progress of the scientific method as something to hype and spin...maybe someday...naaaa probably never happen.

    It would be an interesting read, I suppose one would have to join the collaboration to *ride that train*. right?

    dorigo
    ... right.
    Παρεπιπτόντως,  you remind me of something I have thought about in the past. People in HEP time and again have expressed their wish that data be made public after the demise of these large experiments. I agree, but I would add to the plate another very important thing, namely the large number of internal documents that the collaborations produce during their lifetime.

    In CDF there are a total of about 11,000 such internal notes. Mind you, these are much closer to actual publication-level papers than what one could at first think. I remember the first such note I co-authored: it was a summary of the first search for all-hadronic top quark pairs in CDF Run 0 data. It was 1992, and we wrote a 40-page document which took us a couple of months to review among ourselves (a group of a dozen physicists from two universities) before we "released" it -internally!

    I think the CDF-NOTE database is a great example of a wonderful mine of knowledge, which should by all means be made public after the experiment ends. I believe that all documents except the first 2500 are available in electronic form; the first quarter of them could be scanned with a minimal investment. Further, the CDF data will be much more understandable and useful if released one day, if the internal notes are also released together with them.

    CDF will stop taking data in September. The collaboration will continue to produce interesting physics results for at least a couple more years (but I am willing to bet more like four or five). I am going to check with the CDF spokespersons if there is a plan to release the CDF-NOTE database to the public domain in, say, a couple of years from now. Will let you know about the outcome.

    Cheers,
    T.
    dorigo
    ... right.
    Παρεπιπτόντως,  you remind me of something I have thought about in the past. People in HEP time and again have expressed their wish that data be made public after the demise of these large experiments. I agree, but I would add to the plate another very important thing, namely the large number of internal documents that the collaborations produce during their lifetime.

    In CDF there are a total of about 11,000 such internal notes. Mind you, these are much closer to actual publication-level papers than what one could at first think. I remember the first such note I co-authored: it was a summary of the first search for all-hadronic top quark pairs in CDF Run 0 data. It was 1992, and we wrote a 40-page document which took us a couple of months to review among ourselves (a group of a dozen physicists from two universities) before we "released" it -internally!

    I think the CDF-NOTE database is a great example of a wonderful mine of knowledge, which should by all means be made public after the experiment ends. I believe that all documents except the first 2500 are available in electronic form; the first quarter of them could be scanned with a minimal investment. Further, the CDF data will be much more understandable and useful if released one day, if the internal notes are also released together with them.

    CDF will stop taking data in September. The collaboration will continue to produce interesting physics results for at least a couple more years (but I am willing to bet more like four or five). I am going to check with the CDF spokespersons if there is a plan to release the CDF-NOTE database to the public domain in, say, a couple of years from now. Will let you know about the outcome.

    Cheers,
    T.
    If someone were to make a Freedom Of Information request, could they refuse it?

    dorigo
    Oh, sure they could. What would however be the basis of the request ?
    T.
    Vladimir Kalitvianski
    First, information should not be disinformation.
    Do you need to specify a basis? I thought you just submit a request and they have to find a reason not to comply. For example they may say that the documents are not owned by the government agency. I suppose they have it covered somehow.

    In reply to a request from the Republican Party under the state of Wisconsin's Open Records Law, asking for all of a professor's emails relating to a certain subject, the Chancellor of the University of Wisconsin-Madison wrote:

    "We are also excluding what we consider to be the private email exchanges among scholars that fall within the orbit of academic freedom and all that is entailed by it. Academic freedom is the freedom to pursue knowledge and develop lines of argument without fear of reprisal for controversial findings and without the premature disclosure of those ideas. Scholars and scientists pursue knowledge by way of open intellectual exchange. Without a zone of privacy within which to conduct and protect their work, scholars would not be able to produce new knowledge or make life-enhancing discoveries."

    Although the case law may be different for the Freedom of Information Act, and there are probably several other reasons why such a request would not apply, I think this paragraph that illustrates why such requests are never a good idea.

    Hank
    You are making a philosophical point (as was the Chancellor) and the courts will make a legal one.   The government can mandate admission policies at universities, the courts have ruled, because schools are de facto extensions of the government due to government funding.    That means journalists who request emails and documents all of the time under the auspices of knowing what people who get taxpayer money are doing will be allowed to do it if the academic gets any federal money - and that is the essence of Freedom of Information.   For researchers to try and claim they are under a special protection no one else, is both legally silly and would veer toward an academic being on every government committee so they could hide whatever needed to be hidden.  This just never came up before but one big-mouthed professor with a political agenda will spoil it for everyone.   
    In fact, the chancellor's stance was based on Wisconsin case law. I have no idea whether the federal situation is the same.

    Hank
    Sure, but a Chancellor's stance really means very little.   If the Chancellor decided no more black people would be admitted to the university, it would hold little legal weight regardless of whether or not he could find a Wisconsin case that rationalized it.     To my knowledge there is only one university in America that accepts no federal money so they would be exempt from Freedom of Info requests.    Passively 'denying' freedom of information requests (by ignoring them) is what got some of the climate science people in trouble.

    The advantage a HEP person has is that they can simply give over everything; 'here, take all 10 inverse femtobarns of collisions.  Enjoy!'
    dorigo
    Hah, yeah - I'd love it if a senator asked for our data. We'd shove it in a hundred million bulky emails and forward them to his account, a dozen a second.

    Cheers,
    T.
    dorigo
    Yes, I think so. And remember, these are international collaborations, not ones funded by a single body.
    T.
    Do visiting scientist have access?, I would gladly sign a oath, surely there is a way around this (being a person with high morals, standards, and ethics, that I am) without actually joining the colab.

    Or I guess I could just wait.........

    Oh, I forgot to add that I sometimes find errs and mistakes or dead ends more educational than just a boring correct answer to the correct question, sometimes asking the wrong question can lead to new discoveries, eh?

    My collaboration is being unfairly impugned.

    What would you suggest? That every time there was a rumor in the blogoshpere, ATLAS should be prodded into publishing a rebuttal? So that some "leaks" can hold the collaboration hostage, endlessly?

    We all know the web exists, but that doesn't mean scientific inquiry has to be constantly adjusted, simply because some guy has a blog somewhere. You are sounding a bit like the mass media, when it pontificates about the effect of mass media. If everyone would stop blathering on about how important such and such is, it would immediately cease to be "important". Some things are important by right. Others are just hype. It is hardly reasonable for a large scientific collaboration to chase after hype. When ATLAS publishes a Higgs result, then we can discuss an ATLAS Higgs result. Anything else is futile chatter.

    dorigo
    Dear anonymous Atlas member,

    of course I am not suggesting anything to Atlas. I have restricted myself to noting, in the post above, that the document, although 100% motivated by the leaks, does not mention them as the reason for its existence.

    Can you deny that Atlas would never make such a "come from nowhere, lead nowhere" document on such an important topic if it were not to address the leak ? Of course not.

    So it stroke me as a bit odd that the document would not mention the reason for its own publication. Typically this is one of the very first things that a paper addresses: why am I published ? What is the rationale behind this physics analysis ? You know this stuff of course, but in your post you diverge, saying that Atlas cannot bother to follow the web. That was not the question.

    Cheers,
    T.
    You protest too much. This was not simply a rumor floating around the intertubes - it was largely based upon a document which NS claimed to have been provided by someone at CERN and IIRC, within Atlas. No document and then yes, its just a lot of hot air speculation which would die off on its own (and likely not reach the level it did.)

    Anonymous, you may be surprised to learn that there are many outside of the collaboration that have great interest in your work, and the blathering whether negative or positive keeps this interest alive. Yes the media can be quite harsh in their attempt to get the really good scoop, who can blame them? I (personally) think it was highly commendable that the Atlas collaboration addressed the leak in the manner that concentrated on the webs.

    Don't you think since the webs originated at Cern, that more involvement with the community that it serves will help stabilize the noise/hype relationship and these *spikes of hype* will be lost in the background and the public will gradually be more educated? That has to be a good thing.

    It is that futile chatter that keeps interest in the discovery of the Higgs mechanism.

    Hank
    Anonymous, you may be surprised to learn that there are many outside of the collaboration that have great interest in your work
    And the opposite would be much, much worse.  Any researcher who thinks the taxpayers and the public exist to fund his dream of doing experimental work is a bit goofy - but science has many goofy personalities who think just that way.    Some sciences go way over the top in hyper-promoting speculation (astronomy and its monthly 'life on other planets' nonsense) but physics is usually rather reserved, especially when it must be noted that results and claims are often argued over and compromised on and the public doesn't have much stomach for science by consensus.    Letting them see a little something here and there under the hood is not bad, it shows people how science works.
    Excuse me a little bit, I am no professional physicist (although I have a pretty good formation in mathematics) and moreover English is not a language I use frequently, so I can express myself inadequately. But I was asking a question, which, perhaps, express only my lack of serious knowledge of the subject.

    I have once discussed with a physicist who was specialised in quantum mechanics rather than particles' physics but who had sometimes the occasion of discussing with colleagues about the present subject and he told me that the phenomena that appeared in particles' accelerators were very complex and not perfectly understood, because they were often only indirectly observed.

    This been said, wouldn't it be possible, taking into account the complexity of the phenomena and the fact they are not perfectly understood, that some small differences between experiences (Atlas and CDF, LHCand Tevatron), or some subtle events be observable in one of this experience and not in the other one, or that they be observable at a certain energy and luminosity ad not when energy or luminosity of the experience is modified ?

    As a matter of fact, the best understood phenomena can be observed, as it seems, in every circumstance, but is it necessary, that it be the case for all ? Or to speak perhaps a bit dialectically, wouldn't it be possible that the same physical principle, still to be discovered, manifest itself in one case by an excess at 115 GEV and in another case by a small deficit at the same level of energy ?

    dorigo
    Dear Robert,

    the answer is simple. As physicists we are interested in universal phenomena, whose existence does not depend on the detail of our experimental procedures, and which can be observed if a sufficiently powerful and precise apparatus is used. The first requirement is just a principle of universality, which says we are interested in understanding the rules of the universe and not its exceptions; the second requirement is a principle of repeatability, without which science cannot be made.

    In the specific instance: if a Higgs boson existed with the characteristics of the ATLAS tentative signal, there is no chance that it would escape analysis at CMS, or even in the Tevatron experiments (their datasets and experimental environment would be at the edge of detectability of that signal, but more data can be analyzed there in the forthcoming months).

    Cheers,
    T.
    Can Higgs boson explain momentum, inertia and moment of inertia? Can it explain gyroscopic effects? Can it explain dark matter? LHC cannot announce a breakthrough because there is none from their side; rather, they are now working on an exit plan after the USPTO screened my application for two months under secrecy review. Quite probable that LHC got a whiff of what was brewing at the USPTO. The actual discovery of gravity’s exact mechanism along with that of dark matter has already taken place, way back in autumn 2010. I know from my theoretical understanding that it is impossible to find any traces of Higgs boson as a quantum particle in the Hadron collider, neither can it show the existence of dark matter. Some details of my discovery of how gravitation exactly works are on http://www.anadish.com/ ; details of how it is produced in the framework of quantum mechanics has been disclosed to the US Patent Office and is to be published by them as a patent application. I consciously did not report to any peer-reviewed journal, fearing discrimination, because of my non-institutional status as a researcher. I had filed the US patent application (US 13/045,558) on March 11, 2011, after filing a mandatory Indian patent application on January 11, 2011.