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| | 3 | Yes, you can, the shape of distributions are kept. However the normalization change. |
| | 4 | In the case you use scalefact and alpsfact in the run_card, this change of scales can be compensated by using the parameters %$PARP(64)$% and %$PARP(72)$%. |
| | 5 | Let's see this in more details: |
| | 6 | |
| | 7 | For ME, the parameters are as follows: |
| | 8 | * scalefact multiplies the (linear) factorization scale and |
| | 9 | * for non-matched production also the renormalization scale since those are set equal in this case |
| | 10 | * for matched production the renormalization scale of QCD vertices that are not considered "extra jet" vertices |
| | 11 | * alpsfact multiplies the renormalization scale for extra jets for matched production only. |
| | 12 | |
| | 13 | For Pythia, the parameters are: |
| | 14 | |
| | 15 | * For spacelike showers: PARP(64) is factor of %$K_{T}^{2}$% (note squared, so alpsfact=2 corresponds to PARP(64)=4) |
| | 16 | * For timelike showers: %$\Lambda_{QCD}$% is given in PARP(72), so this value should be multiplied by 0.5 when alpsfact is 2, and by 2 when alpsfact is 0.5. The default value is 0.25 !GeV. |
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| | 18 | -- Main.SimonDeVisscher - 02 Mar 2009 |
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