beam-electron energy in e-p collision
Hi MadTeam,
I am simulating an e-p collider and have encountered a problem, which is simply observed in the following procedure:
~~~
generate p e- > j ve
launch
parton
done
set lpp1 1
set lpp2 0
set ebeam 500
done
~~~
Then the generated file "unweighted_
<init>
2212 11 5.000000e+02 5.000000e+02 0 0 247000 247000 -4 1
1.737900e+02 5.129000e-01 1.737900e+02 1
<generator name='MadGraph5
</init>
However, the electron energry in <event> tends to be larger than this beam energy:
<event>
4 1 +1.7379000e+02 4.21935200e+01 7.54677100e-03 1.49266300e-01
2 -1 0 0 501 0 +0.0000000000e+00 +0.0000000000e+00 +6.6401004881e+00 6.6401004881e+00 0.0000000000e+00 0.0000e+00 -1.0000e+00
11 -1 0 0 0 0 -0.0000000000e+00 -0.0000000000e+00 -5.0000043526e+02 5.0000043526e+02 0.0000000000e+00 0.0000e+00 -1.0000e+00
1 1 1 2 501 0 +7.0682493961e+00 +4.1597274055e+01 -7.4166341584e+01 8.5328421890e+01 0.0000000000e+00 0.0000e+00 -1.0000e+00
...
Here, the electron energy is 500.00043526 GeV.
Why does this happen? Physics, floating-number precision, or some bugs?
Additional notes:
- This may be related to this question: https:/
- This is not observed in ee colision.
Best,
Sho
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