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    Higgs Live Blogging 5 - Draft Quotes For The Guardian Etc.
    By Tommaso Dorigo | July 4th 2012 01:31 AM | 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 first three entries of this live blogging series are available here (part 1) and here (part 2) and here (part 3) and here (part 4)].

    Ian Sample, a science journalist from the Guardian, asked me for some quotes. I offered him a choice, as follows.

    - This is evidently a discovery of a new particle. If anybody claims otherwise you can tell them they have lost connection with reality.

    - Is it a Higgs boson or not ? Well, it has been found using techniques tuned for the standard model Higgs. A different object might have stepped in, but it is quite unlikely in my humble opinion. It could however be a Supersymmetric Higgs. Sure, it could - but I have said it several times that I do not believe in that beautiful theory.

    - CERN should really build a larger auditorium ! The present one is nice and cosy, but it is embarassing and sad to see many distinguished colleagues queueing up at five in the morning knowning that they have a slim chance to get a seat, after working for twenty years on finding the Higgs boson.

    - The fact that the discovery has leaked in any conceivable way out of the hands of the experiments, despite all efforts to contain it, should teach us a thing or two. This is a new age and information control is not possible. In basic research we should just acknowledge the fact and try to be more open-minded.

    By the way, speaking about the press: I should also mention that I have just written a piece for the italian newspaper "Il Manifesto". It will be published tomorrow...

    8.30 AM: the room I am sitting in is getting filled up completely. This is one of the four basement-floor conference rooms of Building 40, the headquarters of the ATLAS and CMS experiments. In this room most of the CMS Higgs searches have been discussed in the past six months.

    8.40 AM: Some more bits which might help you understand what will be broadcast.

    - I believe the event will start in 20' with a brief introduction, followed by Joe Incandela's talk. Joe is the spokesperson of the CMS experiment. He will be speaking for 46', i.e. one minute more than Fabiola Gianotti (who is spokesperson of ATLAS and who comes next). The extra minute is an agreement between Joe and Fabiola: CMS had the right to go first since in December ATLAS went first, but then Fabiola asked Joe if he can introduce the Higgs production and decay phenomenology for both..

    - What kind of plots will you see ? Which will be the most important ones to stick your attention to ? Well, for sure you will see reconstructed invariant mass distributions for the H->gamma gamma and H->ZZ->four lepton decay modes. The most striking will be the H->ZZ plots, which have little backgrounds and will show a clustering of events at 125 GeV, which will follow the Higgs predictions and will be mildly incompatible with the flat background distribution.

    - You will also see the gamma-gamma mass distributions as falling exponential shapes with very faint signals at the right place. By itself, none of these subchannel plots will really convince you that the Higgs boson is there. A complex statistical analysis is needed for that...
     
    - You will see figures that show the signal strength broken down in the various contributing channels. These will not be impressive, since each channel by itself does not allow to measure the signal rate precisely yet, if we exclude the two most sensitive decays (gamma gamma and ZZ to four leptons).

    - There will of course also be "brazil band" plots. These have as distinguishing feature a green and yellow band cutting the graph horizontally, and wiggling around. That is the expected upper limit on the signal rate that the experiment expected to set as a function of the unknown Higgs boson mass (well, unknown... you know what I mean), if the Higgs is not present in the data at each hypothetical mass value. The black curve overimposed to the band will show you that the data is compatible with the background-only hypothesis, everywhere except in the region around 125 GeV, where the upper limit will fail to go below the horizontal line at 1.0, which denotes the predicted Higgs boson rate in the standard model.

    - Another very important graph will be the one showing the p-value of the observed excess. This again is shown as a function of the Higgs mass. For 125 GeV this p-value curve will show a quick dip toward 10^-7 or 10^-8, where it will get close to the dashed curve which describes the expected p-value in the presence of a signal.