Suspicious Bump

Last night a new preprint from CDF appeared at the arXiv, discussing a signal observed in their data, at about 3 sigma significance, that could in principle correspond to a new particle not seen or predicted before. This morning’s New York Times has an article about this here. The Times does a pretty good job of getting quotes from relevant experts and explaining the situation, which is basically “if it’s real that’s very exciting, but it probably isn’t”.

I went to check Tommaso Dorigo’s blog only to find that he had a short posting up explaining that a more detailed one was embargoed until the public talk this afternoon at Fermilab (live stream at 1600 CDT here). This seemed rather odd since the Times had clearly been given the story a few days ago, embargoed only until last midnight. He now has a full posting up, and you should go there for a detailed and authoritative look at what this all means (most likely not much, modeling the huge background you have to subtract is hard).

Update: For other blog postings about this well worth reading, try Michael Schmitt, Resonaances, Gordon Watts and Flip Tanedo.

Update: Took about 21 minutes from the time of release of this data to submission of a paper explaining it.

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20 Responses to Suspicious Bump

  1. Tommaso says:

    Thanks for the link and the kind words Peter. Indeed, I had promised somebody in CDF that I would not blog on this until it was public.
    What do I know… First of all Viviana Cavaliere’s thesis contains all the information of the paper -actually ten times more, and that one is public since a while ago (note that it caused a theoretical paper hypothesizing a Z’ signal in CDF to be produced by April 1st).
    Second, the NYT piece. And third, the paper is in the arxiv but the seminar hasn’t started yet. Oh well.

    So, this is no higgs. This might be the Z’, but it is orders of magnitude more likely a JES problem mixed in with a W+jets background simulation mismodeling…

    Yet it is nice that CDF is not afraid to publish these kinds of signals any more – ten years ago they would rather sit on such a thing and die than publish it.



  2. Michael says:


    I also applaud the CDF Collaboration for bringing this out reasonably quickly. It is not shody work, and so other collaborations (D0, CMS, ATLAS) should be motivated to check for a corresponding signal. Good since, for sure.

    In my opinion, if it is not real, then it is a statistical fluctuation rather than a problem with modeling the background or with the jet energy scale.


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  4. Kea says:

    Well, the 21 minute paper has an abstract quoting the 2010 thesis sigma of 3.2, as opposed to the new paper sigma of 3.3. This suggests that the paper was already prepared, and rushed onto the arxiv to beat competitors.

  5. lcs says:

    I would be more convinced if both electron and muon Mjj distributions showed equally convincing bumps. At least in Fig. 7.1 of Cavaliere’s thesis this is not the case.

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  7. abbyyorker says:

    Negative spin would say that it is hype driven by the imminent shutdown. Rather a nasty thing to say, I admit.

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  9. AR says:

    The paper you cite was not the first paper explaining the data. There were two theory papers even before the CDF paper came out (arXiv:1103.6035 and arXiv:1104.0243). The analysis had already been published in a thesis.

  10. jo says:

    Off-topic: there’s a pretty pompous-looking string theory conference next may at IHES, invoking “three generations”

    No Witten nor Maldacena though: it would be interesting to know if they can’t attend, or don’t want to attend…

  11. Peter Woit says:


    I don’t know about “pompous”, lots of those people have done very interesting things, many of them with nothing to do with string theory, and if I wanted an excuse to go back to Paris, there’s plenty of talks by that group I’d like to hear.

    What is kind of funny is the “three generations” thing. If one wanted to, I suppose you could start with the people who first worked on string theory circa 1970, find their students, their student’s student’s etc, and have a conference on “six generations of string theory”. Pretty impressive for an idea that doesn’t work…

  12. Jurgis Rudkus says:

    Hey Peter, have you watched the wonderfully combative interview Brian Greene recntly did with Amir Aczel? Greene fared quite well, though he had to work for the win. In fact, Greene dispensed with most of the objections you’ve raised on your blog in a lucid, congenial, and complete fashion. I haven’t felt this good about the multi-verse in years. Check it out!

  13. Peter Woit says:


    No, I hadn’t seen that, thanks for pointing it out to anyone who wants to follow it. I have to admit though that I think I’m pretty well conversant with the arguments of Brian and other multiverse proponents (I’ve read about half a dozen books on the subject now, including his…). So, I’ll skip this. If someone who does watch it hears a new argument not gone over endlessly already, let me know…

  14. Shantanu says:

    Peter, I thought you said Brian and you agree on most things.
    (looks like multiverse is not one of them)

  15. Peter Woit says:


    I don’t think I disagree with Brian and most string theorists about what the actual state of the subject is, when you get down to precise questions. I’ve always disagreed with them about the likelihood of the kind of future progress needed to overcome the well-know problems they have. When it comes to the multiverse, this is even more true, and I suspect that actually the majority of string theorists are skeptical that the obvious problems with it can be overcome.

    But, enough about the multiverse here, surely a posting where it is more relevant will come along soon…

  16. kelly says:

    Now that the major media has taken this report and run with it (and oh what a run!..) all the good physics blogs have gone silent! Common guys, lets hear some follow up! Don’t be afraid, the ball is already rolling, you can blame Tomaso, let’s hear some speculation on what confirmation of a new boson or force could mean! And I don’t mean technicolor strings!

  17. Peter Woit says:


    I’m not sure what follow-up is needed to reporting that there’s almost surely nothing here. As a follow-up though, it still looks very likely there’s nothing here…

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  19. James says:

    Peter: I enjoy your blog and I’m reading “N.E.W.” now. I wonder, is this article at all relevant to the Fermilab “bump”?

  20. Peter Woit says:


    Glad you enjoy the blog. Looking at that paper, it “predicts” that the mass of such a Z’ is above 30 TeV, beyond even the scale accessible at the LHC. So, the Tevatron bump can’t be it.

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