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Edgar Carrera | USLHC | USA

View Blog | Read Bio

Immediate rediscovery of physics

The CMS Collaboration has made public the preliminary plot that shows the di-photon resonance (pi0). Enjoy!!

Edgar Carrera (BU)


  • Nathan L

    Wikipedia tells me that the mass of the neutral pion is 135 MeV. What gives? Is the calibration off?

  • Blake

    Cool! Congratulations! Why is the peak at 116 MeV and not 135 MeV, the rest mass of a Pi0? -A (curious) non-physicist

  • Tom

    I’m no expert in physics but
    I’ve had ateast 1 upper diviSion course. What foes this mean?

    I’ve also noticed on a couple of the collision 3d screen grabs that the there’s an obvious red jet that’s not found in the other shots. Would you mind explaining this a bit. It would be really cool to see an annotated shot of a collision with small notes and perhaps equations and links to wikipedia or more details.

    One last question. Which technology and science areas do you and other scientists feel will be most influenced by the discoveries? Energy, computing, healthcare, etc… and why?

    Thanks a million!!! Exciting stuff!

  • Nice. What’s the next particle to find after pi0? The J/psi or maybe the W or Z?

  • vivek

    why is the mass so far from the nominal value? It is too low by almost 20 MeV!

  • Carl Carly

    Why is the mass wrong?

  • Curious

    Why is the mass of the peak not at the known pi0 mass?

  • Vivek Jain


    I had left a comment last week, but I guess the easter weekend intervened. Also, I logged into the blog site, but don’t see my comment as pending, so I don’t know what happened.

    In any case, why is the mass of the pi0 off by 20 MeV? That seems kind of a large shift.


  • Thanks a lot for all your comments. The reason why the mass is not death on on the nominal mass is because the plot was made with the “out of the box” tools. No corrections for clustering/containment are implemented in this plot. It is basically an on-line plot. One of the tasks for CMS experts right now is to fine-tune (calibrate) the detector, and for that these known resonances are extremely useful. The fact that we are so close to it “as is” is very encouraging.

  • Sure, J/psi, W, Z you name it, life will be even more exciting then..

  • Hi,
    If you are talking about this one, that is actually a muon in the endcaps.
    As far as the areas that will be influenced by our possible discoveries, I am sure Energy will be one for sure. Computing and healthcare have been already influenced directly and indirectly.


  • Sean Vostinar

    Would you please describe the relationship between the plotted graph and the event display? Do the blue and red plots simply correspond to the Hcal and Ecal?

    Also, here’s a repost (it was new to me!) of a link that explains how to interpret the CMS event display.