Wednesday 4 July 2012


CMS and ATLAS both now have conclusive evidence of a Higgs-like particle with a mass of around $125-127$ GeV; this will be covered all over the internet, so I won't go into details here. I will say that it's a thrilling moment, and that we all eagerly await more data, to elucidate the detailed properties of this particle.

But the main reason for this post is to publicly congratulate everybody involved in this work. There are (at least) two distinct groups of people to highlight:

  • The LHC is an extraordinary machine, and has been performing phenomenally well; this discovery is only possible now because the machine has delivered so much integrated luminosity so quickly. It represents an unparallelled engineering achievement, so congratulations to the team who have worked so hard to get it to this stage.
  • ATLAS and CMS are two of the most sophisticated experiments ever, in any field of science,* and this result is testament to the tremendous skill and dedication of the experimental teams. Each consists of thousands of people — congratulations to you all.
This is a great day for science, and we should remember the huge amount of work which has been required to get here.

*I don't make this remark flippantly. The two LHC beams cross inside each detector approximately once every 30 nanoseconds, and each crossing can produce up to about 30 distinct interaction events. This results in far too much data to collect, so the machines have to sift out the different events and decide in real time which ones are interesting enough to record. Considering that all of this comes on top of the intial challenges of measuring charged particle tracks, energy deposits etc., without the equipment simply being destroyed, describing these experiments as "impressive" is an enormous understatement. I haven't even mentioned the simulations and data analysis necessary to actually extract a signal once the data has been collected…


  1. "CMS and ATLAS both now have conclusive evidence of a Higgs-like particle ..." CMS/ATLAS claim that they have evidence of a boson with spin 0 or spin 2. I see several reasons for believing them:
    (1) The relevant experts are nearly unanimous in support.
    (2) Two competent, independent teams have reached a similar conclusion.
    (3) The discovery signal has improved as more data has been collected.
    However, could unknown SU(5) physics (or SU(8)) physics somehow create a false signal? Has Sheldon Glashow been convinced that there is a Higgs-like boson?

  2. W against T, reference required. #conspiracyofscience


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