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CERN | Geneva | Switzerland

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Getting closer to finding out if the Higgs exists

CERN has been in effervescence for the last few weeks, with rumors running wild and hopes flying even higher. In fact, for the past few weeks, the physicists from ATLAS and CMS, the two collaborations looking for the Higgs boson at the Large Hadron Collider (LHC), have known half the answer. The problem is that the truth lies in knowing the other half, which will only be known officially at a special seminar organized by CERN director general on tomorrow December 13 at 14:00.

What can we expect to find out next Tuesday? Already, in November, the first combined results from the two experiments were released based on 40% of all collected data, excluding large values of the Higgs boson mass. This means, we now know better where to concentrate our efforts.

Looking for the Higgs has kept physicists on their toes for decades. In this case, the theory predicts the existence of this particle. Finding it would be one more confirmation, and a very strong one, that the theoretical description we currently have, the Standard Model, is correct.

At this point, the region at low mass, between 114 and 141 GeV, is where we expect to see something. The Standard Model predicts how many Higgs bosons should be produced at a given mass, and how many of them will decay in a specific way, but it does not tell us its mass. So CMS and ATLAS are searching blindly, not knowing exactly where to look, but also searching using all possible decay modes.

In the low mass range, three different decay channels contribute the most, namely when a Higgs boson decays into two photons, two Z bosons going into four leptons, or two W bosons decaying into two leptons and two neutrinos.

How and when will we know if we have indications from the Higgs boson? If one experiment sees hints of the Higgs boson not only from one channel, but two or even three of these channels, then it’s encouraging. Even better, if not one but both experiments see such signs, and both see them at the same mass, it’s time to call your mother.

This is very much like trying to catch a faint radio signal. We suspect this hidden radio station exists but nobody knows at which frequency it broadcasts. If one search team hears a weak signal using a crystal radio at a given frequency, this is one thing. But say another group also catches something independently at the same frequency using a digital radio, it gets more interesting.

For the Higgs boson, each decay channel represents one different type of detecting technology. Since CMS and ATLAS are looking without telling the other group what they have, if the results that will be presented tomorrow are similar, it could be an indication on the presence of the Higgs boson. But caution will be exerted until we have the irrefutable proof of its presence.

So, stay tuned on December 13 to find out what we have so far…. I will be tweeting live like a little bird from the seminar so you can follow the action as it unfolds from the @CERN account. My colleague Aidan Randle-Conde will be blogging live on the Quantum Diaries site. The seminar will also be broadcasted live from the CERN home page. I will also report the results here towards the end of the afternoon.

Pauline Gagnon

To be alerted of new postings, follow me on Twitter: @GagnonPauline or sign-up on this mailing list to receive and e-mail notification.

 


 

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15 Responses to “Getting closer to finding out if the Higgs exists”

  1. Jayeeta says:

    I’ll be following all the tweets tomorrow.Feeling very excited!!!

  2. rohan says:

    excellent work. am sure cern will crack the nut.

  3. lepton says:

    At the following address

    http://www.science20.com/alpha_meme/light_higgs_discovered_and_about_destroy_universe-85357

    you will find the following information:

    “ATLAS has a 3.5 sigma excess at 126 GeV while CMS has 2.5 at 126 GeV, combined perhaps 4.3 sigma for the 10/fb data, according to rumors [...]“

    • Pauline Gagnon says:

      Rumors are worth what they are… their weight in rumors.

      The numbers you quote are not quite exact, plus taken out of context. These are close to the real local values (without the “look-elsewhere effect”) but this is sort of inflated.

      But the signs are there, no need to twist the number and attempt home-made combination. In a few months time, we will be able to tell. No more guessing will be needed.

      Pauline Gagnon.

  4. RG says:

    Sounds like a PR/funding stunt to bleat for tax payers cash whilst people are losing their jobs/homes. Massive waste of resources. The best and the brightest all grubbing around for their five minutes of science factor fame courtesy of the tax victim.

    • Thor says:

      Waste of tax money:
      Religion (Should be banned from the public)
      Culture (Globalization will kill the “unique identities” sooner or later)
      Military (Speaks for itself)

      NOT waste of tax money:
      Research/development for a better understanding/technology/methods which can and WILL play a major role in shaping our future for the better. (Examples include fitting together puzzle pieces of physics (CERN), fusion reactors (ITER), Thorium reactors (TEA), quantum batteries, better solar panels. the list can go on forever!)

      TBH Research like I mentioned is not even close of getting enough resources and attention as they should!

    • Hamish says:

      Sometimes I wish that particle accelerators worked like they do in Hollywood. transporting people into alternative dimensions and the like. Then we could find one such dimension in which everyone thinks the same way as RG does — and dump him/her there. Poetic justice!

    • Tobeface says:

      Well RG if all that money hadn’t have been “wasted” in trying to understand the fundamental constituents of our universe then beneficial offshoots like hmmm the INTERNET wouldn’t have been created and morons like you wouldn’t have anywhere to voice your small minded opinions. CERN is worth every penny.

    • Skulpti says:

      What an even tinier world RG must live in.

    • John Siviour says:

      This comment reflects the lack of understanding much of the populous has of the benefits of research. This presents an opportunity for researchers to engage with the larger community in explaining the benefits of research in general.

  5. Lorenzo Z says:

    Very exciting! Can`t wait!

  6. Ad says:

    Yes, damn those attention whores who created the World Wide Web!
    Nothing HAS ever come from those people!

    I rarely comment on blogs, but RG please get informed.

  7. Ganesan says:

    Great day.

  8. [...] release here. More at two blogs, Quantum Diaries and Resonaances. The former (Pauline Gagnon’s post) points to various live sources that will [...]

  9. Zak says:

    I think the research is valuable, but all the hype surrounding the Higgs is ridiculous.

    First of all, ALL subatomic particles are required for the universe as we know it; there’s no particular reason the Higgs is more crucial than the rest.

    Also, they are finding it pretty much exactly where they expected it to be. So, essentially, they are just CONFIRMING what has been strongly suspected for decades. There is really nothing new here, except a huge PR exercise to justify funding.

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