News From Chamonix

The people responsible for the LHC are meeting in Chamonix this week to make plans for the upcoming run, slides of many talks are available here. The results of discussions there are:

  • The recommendation will be to run at 3.5 TeV/beam, not increasing to 4 TeV/beam as widely expected.
  • The long shutdown to fix splices and allow going to 7 TeV/beam will be delayed until 2013, with 2012 devoted to a physics run. The 2013 shutdown will likely last more than a year.
  • Officially, the integrated luminosity goal for 2011 remains at 1 inverse femtobarn. However, unofficially, they expect to be able to do at least twice this, ending up with 2-3 inverse femtobarns by the end of the year
  • For a discussion of the possible physics that can be done with these parameters, see here. By the end of 2011 the LHC should be able to do better than the Tevatron on the Higgs search over most of the possible mass range, except for the low end of the range, where higher energy isn’t much help, and the Tevatron’s more than 10 inverse femtobarns and longer experience with the data analysis may give them an edge.

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    6 Responses to News From Chamonix

    1. Anon says:

      Particularly noteworthy is the plot on slide 19 of the talk linked above – the first public limits on SUSY from ATLAS, obtained from the same data-taking period as the CMS plot on the previous page. Results from the analysis of other channels still to come …

    2. Tommaso says:

      Hi Peter,

      I think CMS and ATLAS will actually win the race even in the range of masses where the Tevatron is advantaged. This stems from the recent re-evaluation of sensitivity performed by the two experiments. Also note that ATLAS and CMS might in principle decide to combine their limits or significances, something that the Tevatron does systematically.

      A few pictures are worth thousands of words: see the CMS expected 3-sigma reach and 95% exclusion reach in 2011 for some scenarios here.

      As you can see, 2/fb at 7 TeV will still allow to reach 3-sigma in a wide range of masses (130 GeV onwards), or to exclude a region down to 120 GeV or so at 95% CL. Combining with ATLAS, which has a similar sensitivity, will do the rest.


    3. Pingback: Una pena, la propuesta final para el LHC del CERN durante 2011 no contempla colisiones a 8 TeV c.m. « Francis (th)E mule Science's News

    4. hg says:

      In all the talk about searching for the Higgs at the LHC, what happened to the LEP signal for a Higgs at 114 GeV?

    5. Rhys says:

      hg, nothing ‘happened to it’. It’s still talked about, and many people (especially those of us keen on supersymmetry) think the Higgs is probably quite light, by which I mean in the 110-130 GeV range.

    6. Peter Woit says:


      I believe that after final analysis, the LEP “Higgs signal” was about 2 sigma, nothing to get excited about. Hopefully though within the next year or two we’ll find out whether there was really something there. It’s interesting that that Higgs mass is about the worst possible one for the LHC to try and see. Maybe they’ll end their 2012 run with a 2 sigma signal….

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