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A (Event generation) What information do you get...

  1. Jun 7, 2016 #1

    ChrisVer

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    What information do you get by reading that some sample production (like the W/Z for Powheg) is normalized to the NNLO cross sections?
     
  2. jcsd
  3. Jun 9, 2016 #2
    The Meaning on that statement is that the total number of events is normalized to the calculated NNLO inclusive cross section.

    The production itself is done at a lower order (LO or NLO), so the shapes of all the distrubutions reflect these lower orders.

    But the total normalization is accurate to NNLO.
     
  4. Jun 13, 2016 #3

    ChrisVer

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    So the events get scaled by something like this:
    [itex]\frac{\sigma_{LO/NLO}}{\sigma_{NNLO}}[/itex]?
     
  5. Jun 14, 2016 #4
    The total number of events are normalised by [itex]\frac{\sigma_{NNLO}}{\sigma_{LO/NLO}}[/itex]
     
  6. Jun 15, 2016 #5
    So practically:

    [itex] \sigma_{nnlo}/\sigma_{nlo} d \sigma_{nlo} /dX [/itex]

    Where X is the observable. Practically though, POWHEG samples are not actually NLO accurate for distributions, since it's NLO+PS (not fixed order).
     
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