same parameter, different event number, different result.

Dear Kirtimaan,

I ran the same process with same parameters multiple times(p p > w+ w- in sm model).In four of the runs i set events number to 1. In another 3 runs i set events number as 100, 10000 and 1000000. the results are as follow:

cross section(pb) Events
72.5 ± 0.72 100
72.52 ± 0.16 10000
72.57 ± 0.016 1000000
73.38 ± 0.67 1
72.38 ± 0.83 1
71.96 ± 0.7 1
73.06 ± 0.74 1

Why is it that all the results are different? is that normal? some of the diverse is beyond the tolerance range.

I also used another model(EWeff_UFO) to run the process p p > w w w,
the diverse of results is even larger, many times of the error.

 the results are as follow:

cross section(pb) Events
48.36 ± 1.2 1
52.91 ± 2.4 1
51.76 ± 1.3 1
55.69 ± 0.047 100000
55.67 ± 0.047 100000
55.8 ± 0.044 100000
56.1 ± 0.016 1000000

 I want to know the reason for such diverse of results and wether such diverse is normal or not. And is there a link between the accuracy of the cross section calculation and the events number?

Thank you
Best regards

YiCong Sui