ATLAS publish searches with 205/pb

Up to this point most publications from the LHC experiments have been based on the 2010 data of up to 43/pb. Today ATLAS have published their most advanced results yet in two conference notes using 163/pb of 2011 data and 42/pb of 2010 data for a total of 205/pb. The first note looks at the Dijet Mass distribution using just the 2011 data, and the second looks for one muon and missing transverse momentum with 205/pb. No results inconsistent with the standard model are seen but these papers are significant as a sign that we can expect to see a lot more publications from these amounts of data shortly.

The 163/pb of data for 2011 was collected around the 26th of April so the analysis has taken about five weeks. The total recorded data in each of ATLAS and CMS is now around 600/pb

Update 3-Jun-2011: There is now a third conference note on a search for dilepton resonances using up to 236/pb

Update 4-Jun-2011: A fourth note reporting a search for squarks and gluinos using 165/pb is now online.

15 Responses to ATLAS publish searches with 205/pb

  1. Bill K says:

    I did notice a pattern in titles/abstracts of the talks scheduled for PHLC2011. Many of the talks occur in pairs, for example “EWK results from CMS” followed by “RECENT EWK results from ATLAS”. Part of the pattern is that the CMS abstract says “.. using data collected in 2010” while the ATLAS abstract is not given. So maybe we can expect further results from ATLAS based on 2011 data at the meeting.

  2. Luboš Motl says:

    205/pb starts to be a lot, so the “nothing” results start to visibly increase the probability that the LHC will see almost nothing.

  3. Luboš Motl says:

    Wow, I take it back. The dijet paper, at least, looks pretty impressive. They included the picture of the three 3.3 TeV events for a good reason – this triplet as a group is just marginally remarkable.

    There have been exactly three events with dijet energies between 3 and 4 TeV seen. Their dijet energies were 3.32, 3.35, and 3.36 TeV. The probability that if you take 3 numbers between 3 and 4 TeV, all of them fit into a window of width 40 GeV, is just half a percent.

    So I may even claim that there is a 2.5-sigma hint of a particle near 3.33 TeV. I choose this number because it’s easy to remember haha.

    • Luboš Motl says:

      By the way, the sudden possibility to discuss new experimental physics at 3.33 TeV is kind of thrilling. Imagine a similar discussion in a “couple” of years about a detector that may be seeing a hint of a resonance at 3.33 Planck masses. 😉

    • Philip Gibbs says:

      They seem to be teasing us by showing these three events. I wonder how many more there are in subsequent data.

  4. Philip Gibbs says:

    The most interesting results (if there are any yet) will be held back for the conference. I would be surprised if CMS did not also present new results and I hope there will be at least a few using significantly more than 205/pb.

    The real thunder may wait for EPS-HEP 2011, depending on what appears at PLHC I may even book a place to be there.

    • Luboš Motl says:

      I can’t understand why those people in the two competing teams would be willing to wait. For example, assume that the 3.33 TeV dijet signal is real. That was with 163/pb of the data. They have 4 times more than that by now and it should be possible to extract it.

      If you do so, you could find 12 dijet events near 3.33 TeV or so. By a proper calculation, that’s well above a 5-sigma confidence level proof of a particle near 3.33 TeV. CMS, if they also saw it, or ATLAS could instantly become the authors of the most spectacular first real new high-energy result from the LHC. They may beat the other group. Or they may also wait. I think that despite their friendship, the second option is just insane.

    • Philip Gibbs says:

      This increases my interest in the Butterworth seminar on high-pT jets in ATLAS scheduled for Tuesday The abstract suggests it will be relatively mundane results but that could be a smoke screen 🙂 . It will be webcast.

  5. Luboš Motl says:

    Another fascinating thing that was realized by me and at the same moment independently by my reader Dilaton – I was approving his comment after I updated my article.

    The low-energy string model that explained the 150 GeV bump as a Z’-boson – which I accidentally discussed 2 days ago – also inevitably predicts another U(1) boson, Z”-boson, with mass somewhat above 3 TeV.

    Look at the mass at the end of the previous sentence and then at the previous 3 comments above. Doesn’t it sounds like fun? 🙂

    More at my blog. Is someone able to calculate or find in the literature whether the cross section would be in the right ball park?

    • Luboš Motl says:

      Lust et al. predict width of the 3 TeV Z” boson as at least half a TeV which is way too bad – why not just 20 GeV or so? With the half TeV estimate, they say that 14 TeV LHC needs femtobarns for 5 sigma, so this finding would look too sharp and too early..

    • Philip Gibbs says:

      Have you looked at the dilepton paper? Some interesting excesses there, but as always it will require a little more data to be worth getting excited about.

      • Luboš Motl says:

        The dilepton paper doesn’t get that many high E events -going to 1.3 TeV only or so, not a shock for a hadron machine.

        Also, it only looks at electron-neutrino type of final states, coming from new W’ bosons. I don’t really believe this is a viable type of new physics.

  6. Luboš Motl says:

    There’s a third new paper, with dilepton spectrum up to 236/pb or so – there are only events up to a TeV, clearly no visible excess etc. The thing at 950 GeV is much less impressive.

    Just to be sure, things like superpartners are produced in pairs so they’re not producing resonances in dijet or dileptons etc.

  7. […] one from CMS where new searches using 2011 data up to 236/pb are presented. They all correspond to notes already published last week so we know that only new exclusions limits are found. No new physics is forthcoming this week from […]

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