Higgs Hunters Talk

High-energy Slice view with two jets of particles

  • Whoandwhatitis by Whoandwhatitis moderator

    I searched around the forum a bit for this a wasn't able to find something similar to this.

    In Slice view, this one is impressive. There is a "jet" of three particles going off toward one end of ATLAS and a second jet of two particles that exit one of the sides of the detector. Clearly, the jet of two particles has a lot of energy because it runs almost perpendicular to the beam line. If I had to guess, I'd say this jet is the one in Normal view which contains a muon and ends where we see a blue bar, which indicates a massive bottom quark.

    This I'm sure is a stretch, but could the neutrino have caused the lonely white line we see in Slice view? Based on all three views, it looks like the neutrino would be in line with this particle.

    Overall, this is a fascinating object.


  • markbakovic by markbakovic

    I'm no scientist but:

    (and I am assuming here that by "in line" you mean the track at about 10 o'clock, nearly superimposed on the red dashed line)

    If you look at normal view and try to imagine splitting the image along a line through the beam axis, there is no way you can get that white line on the same side of the split as the green line and still have three lines including the blue one on the opposite side. My personal guess would be the centreline of the slice view could be represented in normal view by an axis running approximately 1:30/7:30, which would suggest the track along the red line is one of the three heading upper right in slice view, and the "lonely line" runs nearly 6 o'clock in normal view (ie there isn't really an ocv there, it's just two tracks that pass the same x/y coordinate, but not z).

    I do feel qualified to answer your question though: no, neutrinos do not interact with any part of the detector and thus cannot be represented by lines on the event images. The red dashed line is used to infer the production of neutrino(es) but it only shows the direction of total missing transverse momentum: that could be one neutrino in line with the red line, or 20 spread all around the detector, none of which traveled down the red line (as the line is then merely an average), we have no way of knowing without a complete analysis of the detected particles (of which there were many in this instance if you look at the calorimeter hits, remember we only see tracks with >2GeV on these images) and likely interaction/decay probabilities.

    All that being said: wow, very-nearly-even 5 way tracks: that probably means something interesting!