Cross section in NLO production (gridpack mode)
Dear Experts,
I am curious about the cross section in NLO gridpack production. It seems that the final value of the cross section and uncertainty is related to the value shown after calculating the upper envelope if we increase the event number. (With low event number they could be different)
In mg265 generating gridpack. e.g.
cards: https:/
the value after calculating the upper envelope: 1.039e+05 +- 9.7e+01 pb
final results: 1.034e+05 +- 9.7e+01 pb
But in lhe production, no matter how much events I generate, in lhe file, It seems that the value would not change and it is related to the intermediate result in gridpack.
e.g.
1k events in lhe file:
<init>
2212 2212 0.65000000E+04 0.65000000E+04 -1 -1 325500 325500 -4 1
1.039320782028E+05 9.741180631555E+01 1.178599179620E+05 0
</init>
10k events in lhe file:
<init>
2212 2212 0.65000000E+04 0.65000000E+04 -1 -1 325500 325500 -4 1
1.039320782028E+05 9.741180631555E+01 1.178599179620E+05 0
</init>
So My questions:
1) Why the lhe production choose this value? It seems that this is the intermediate value rather than the final value.
2) It seems that LO didn't have this issue. So I would like to know if this limit in NLO is caused by some theoretical reason, which also means that we can not suppress the statistical uncertainty by generating more events in gridpack mode. Or does it mean the cross section in NLO and it's uncertainty are limited once the gridpack is produced?
3) It seems that the branching ratio from madspin decay is not taken into consideration.
Could you give me some information for these value? I am not sure if I understand these value properly. Thanks a lot!
Best,
Sen
Question information
- Language:
- English Edit question
- Status:
- Solved
- Assignee:
- Rikkert Frederix Edit question
- Solved by:
- SEN DENG
- Solved:
- Last query:
- Last reply:
This question was reopened
- by SEN DENG