CDF Discovers The Graviton!
    By Tommaso Dorigo | April 1st 2010 07:42 AM | 21 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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    The CDF Collaboration blessed yesterday afternoon the results of a search for massive Gravitons decaying into pairs of Z bosons. And it is a startling new result!

    Usually after a blessing (which is the result of a collaboration-wide presentation when the analysis is given a final scrutiny) the results are not immediately made public: this non-written rule has the purpose of allowing the analysis authors to be the first to present the results at a conference or other public event. But the rule written in the CDF bylaws, on the other hand, say that after a blessing the result is public, so for this time I will stick to the written one, and fair play be darned this time... The chances to announce what might be the first evidence of gravitons is too appealing!

    So what is this all about ? It turns out that events featuring pairs of well-identified Z bosons, decaying into electron-positron pairs or muon-antimuon pairs, are exceedingly rare in the standard model, especially if their total mass is larger than a couple of hundred GeV. Because of that, and because of the clean signal these four charged leptons provide, one does not expect to see any such event even in the very large dataset collected by CDF at the Tevatron collider.

    Instead, the recent analysis by CDF has spotted three very clean ZZ events. And they all have a total mass compatible with the same value, in the 850-GeV ballpark! Previous analyses overlooked two of these events because of too tight lepton identification criteria. Below you can see event displays of the three candidates, taken directly from the web site of the CDF analysis (link below).

    Above, event 1. Note the four clean electron signals. The masses of the two pairs are shown in the top right: both are well consistent with the Z boson mass, 91 GeV.

    Event 2 features two electrons and two muons. One electron is in the forward direction and does not have a track pointing to the electromagnetic deposit (shown on the right in the top panel with a pink square). The masses of the reconstructed Z bosons is again in good agreement with the Z boson mass. Note that this event had been previously overlooked because of the forward electron.

    And event 3 has two electrons and two jets. Normally hadronic jets bring in large backgrounds, but in this case the event is very clean and definitely a third candidate for the graviton signal!

    I am unable to quote a significance for the result, because CDF is still in the process of evaluating it in a rigorous fashion. But since total backgrounds are well below a tenth of an event, these three events are almost certain to constitute the discovery of a new, extremely massive object. A graviton might be the explanation, but other particles might produce the same signature: a Higgs boson, for instance! For the Higgs boson, the cross section appears too large, but this, too, requires more careful investigations. CDF could not sit and wait for these more detailed calculations, however, so I think I am not breaking any rule if I say that the blessing of these three events represents a clear indication that this is a startling new discovery!

    It appears ironic that this occurs one day after the Large Hadron Collider comes in operation, at an energy three point five times larger than that of the Tevatron. But this is also probably the reason why CDF decided to come out with the new result exactly today!

    I am currently on vacation so this post is much shorter than I would like it to be. I plan to add a more careful explanation of the whole search here tomorrow, but for the time being you can find some additional information in the web site of the CDF analysis.

    Post - scriptum: in case it is not clear, read the date of this post: this is an April Fool.


    April Fool! Good one.

    I like a good joke, but I never humorate on serious science. If you could enlarge a proton to the size of a basket ball, you would see what appears to be a basket ball covered with ping pong balls. The ping pong balls are photons or particles of light. If you smash this basketball of ping pong balls, the ping pong balls will scatter in all directions, some forming clumps of 2, 3, 4, etc. representing muons, up quarks, wine quarks, whatever. This is the formula for predicting the results E = MC 2. Smashing protons with high-speed particles will produce all sorts of photon groupings but, is not a practical method for detecting gravitons, which are not located within the protons or neutrons but instead orbit the atomic nucleus...Please tell me that this helps....Alfred-

    Hm Alfred, actually not. I think your image of a proton is rather incomplete. Furthermore, it is not clear what you gain by representing elementary particles like clumps of photons. There are good and bad analogies, and yours is not too good in my opinion. But thanks for trying!

    Hey T thanks for reply- I'll clear it for you. The basket ball sized sphere of ping-pong balls is a simple model to help you visualize this. I discovered, with a lab experiments, that protons are made of light. This is not a theory, is a fact with solid experimental results. Matter is made of light. Was not trying anything, was searching. Have also been able to add or remove photons from protons. A fact, not an anology. There is another particle in orbit around the atomic nucleus; the graviton. And how can I prove this that "I" discovered it ? Easy, I'm the only one who knows how it if you have

    Dear Alfred,

    sorry to have to say this, but I would be intellectually dishonest if I did not. You pass the crackpot test with almost the highest grades possible. Please understand that science is something else than sitting on your sofa trying to make sense wit a theory of everything of the few bits of information you have collected in your readings.

    Ok T, explain how the graviton works.....I'm listening..........

    Alfred, nobody knows yet, not even you. There are good and bad theories. Bad theories are unsubstantiated, unjustified, not based on observations. That is all...
    I don't have any graviton theories. I discovered it, I have the facts. Gravity pushes, it doesn't pull. I can demonstrate the experimental results right in front of anyone if they desire....Alfred-

    Alfredschrader: i have be engaged for years to do theories and experiments on anti gravity technology and flying saucer, and i think i will be pleased to see your experiment to verify that gravity is push not pull, and your graviton discoveries.

    Ahmed: I've been ask to speak at a four year college in Florida. I plan a small demonstration there a well as a lecture. Among the questions answered will be how the graviton works, how inertia works, and the source of time itself.....Alfred-

    I was wondering what some of the April Fools post would be. I must say, this is very elaborately done, Tommaso! LOL

    My hat is off to you, sir! ;-)
    nice 1, now i know about april 1, i miss when i wasnt aware of this tradition and belive in this posts...

    LOL!!! So who was first? You, or Jester with his SUSY discovery post? LOL.

    Probably cern, ,
    but much lamer than these two posts...

    "hideous particle from the prehistory of the Universe".......''antineutrinosauruses''...... 'antiparticulosauruses''? Well, I have to say that no one can say that the people at CERN don't have a sense of humor not to mention rich imaginations! lol ;-)

    I have to tell you, even before I read this article, the moment I logged-in and saw the title "CDF Discovers The Graviton!, not only did I know it was an April Fools joke, but I knew who posted it! lol ;-)
    "antineutrinosaurus" sounds like something out of Stanislaw Lem's "Cyberiade", actually

    Now, the title of this fishy post of today should be "CDF discovers _a_ graviton", right? The massless one would still be undiscovered.

    And in related news, the Independent of London had a splendid idea about where CERN would set up the next ring collider:

    I've got to admit, that's funny! LOL
    Yes, his love to CDF is going under control i think...

    Nicely done!
    I had the good sense to scan your article for the words "April Fool" before delving into the article completely because of the April 1, 2010 date posted in clearview at the top of the page. You are quite clever though.

    I actually did discover the graviton particle & this is not an April fool's joke.
    I didn't use a collider with a googleplex of electron volts, I used the equipment in my tiny garage lab.
    Email me if you have questions....alfredschrader@