CMS search for exotics at 5/fb, is that a HSCP at 700 GeV?

Today CMS have delivered a new report of searches for exotic particles including SUSY using datasets up to 5/fb. I dont think I have ever seen so many new results released in one presentation (Eva Halkiadakis). Sadly there are no new discoveries and nothing can be considered to be inconsistent with the standard model, but it would be exceptional if we could not pick at least one exceptional datapoint from so many plots and here it is.

This is from a search for heavy stable charged particles and three isolated events were seen in the same bin at 700 GeV

Update: A video of the talk has now been uploaded. Motl has posted a useful analysis for this plot.

15 Responses to CMS search for exotics at 5/fb, is that a HSCP at 700 GeV?

  1. Tony Smith says:

    Phil says that it is sad that “… there are no new discoveries and nothing can be considered to be inconsistent with the standard model ..”.
    It makes me happy that the Standard Model is to a very large extent quite valid and that the LHC experimenters and data analysts are able to confirm it in such detail.

    there is one thing that stands out to me as possibly not a plain vanilla Standard Model phenomenon: on slide 41 dealing with Multileptons (e,mu,tau) in the Off Z histogram
    the 100 to 150 GeV bin has about 21 events with about 17 expected, an excess of about 20 percent.

    It includes the region of the digamma excesses that are commonly thought of as a 125 GeV Higgs
    of the CDF Wjj bump.


    • Philip Gibbs says:

      I noticed that but lost interest when I realised that the ATLAS recent conference note on the same subject seems to have it the other way round. They have an excess when the Z-veto is not used, I assume that is equivalent to Z-on but maybe it is the other way round

  2. Luboš Motl says:

    Cool, look how tiny the SM prediction is! Can you read the expectation of the number of events in the bin from the graph?

    • Luboš Motl says:

      Right. 0.3 cubed over 3! is 0.45% which is almost 3 sigma locally, see my blog. The blue triangles are better, 0.07 cubed over 3! is equal to 60 e-5, over 4 sigma.

    • Philip Gibbs says:

      From the red triangle we should expect just 0.3 events so three sounds like a lot but it is probably just a bit better than two sigma before lots of trial error (using Poisson I make it a one in 300 chance, how many bins do we see in all the plots of the talk?). It’s just an intriguing fluctuation as the DG would say.

  3. Tony Smith says:

    CMS PAS-EXO-11-045 Figure 6 seems to be related to slide 41 from the presentation. The caption of Figure 6 says
    “… Plots on the left have the Z-veto applied, while plots on the right include leptons from Z decays …”.

    The Z-veto plot on the left looks like the Off Z histogram in slide 41, and based on 2.1/fb has about 21 events observed with about 17 events expected as SM background in the 100 to 150 GeV bin.

    The inclusive-of-leptons-from-Z-decays plot on the right shows no excess in the 100 to 150 GeV bin.

    CMS says “… the usual experimental strategy of SUSY searches – selecting events with large missing transverse energy (ETmiss) – may not be optimal …”.

    Therefore, the CMS results may differ from the ATLAS results because ATLAS-CONF-2012-001 says “… Events with ETmiss [greater than] 50 GeV are selected …”.
    The excess 4 events with 1.7 expected was seen by ATLAS using the ETmiss selection.
    ATLAS did publish (Table 2) events before their ETmiss requirement and saw 24 events with 25 +- 5 expected
    I do not see where they did a Z-veto or no-Z-veto breakdown for the events before their ETmiss requirement, which is what I think would be needed for accurate comparison with CMS results.


  4. Chris Austin says:

    There also seem to be 4 events in the “search sample” for the “single jet channel”, for jet energy between 700 and 800 GeV, in Fig. 2 (a) on page 7 of the recent ATLAS Search for decays of stopped, long-lived particles from 7 TeV pp collisions with the ATLAS detector, with what looks like a negligible background. But from a quick look at the article, I’m not quite sure what the significance of the “control sample” is, possibly these events are from cosmic ray muons.

  5. Kea says:

    Well, 720 GeV could be one of those multi muon (color) Z’ states, I suppose, if it’s real. That means it should be related to the Wjj anomaly, which is also a color Z phenomenon.

  6. Kea says:

    Hmm, the slides are interesting. What do you think of the Tk + TOF plot? Does it restrict these naive SUSY models?

  7. If this is something real, M_89 hadron physics would be my bet. M_89 hadron physics predicts also M_89 baryons.
    Ultra-naiive extapolation is that the masses of ordinary M_107 baryons are just scaled up by 512.

    *For proton scaling would give 482 GeV which is by 1/sqrt(2) factor smaller than 680 GeV in the middle of 660-700 GeV. Could one consider the possibility that the non-perturbative contribution from color magnetic flux tubes is by a sqrt(2) higher than predicted by naive scaling? p-Adic length scale hypothesis favors powers of sqrt(2) but this does not look convincing.

    *For lambda, Sigma, and Xi similar scaling would give 571, 609, 671 GeV respectively. Xi would contain two strange M_89 quarks so that strong production would involve virtual p(89) –> lambda(89)/Sigma(89) + K(89) and lambda(89)/sigma(98) –> Xi(89) + K(89). Objection: why also lighter M_89 baryons have not been observed?

  8. Luboš Motl says:

    See my blog for a stop squark rumor ;-) which my commenter from an unnamed university near Harvard Square says is more robust than the signal in this blog entry…

  9. Lubos Motl says:

    It’s interesting that only now, after having spent many and many hours with various paper on F-theory phenomenology (since Friday), which are really really cool, I began to think about similar events as a stau,


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