[Comphep-common] COMPHEP for excited leptons - confirmation about the checks before production

[Shilpi Jain]

Dear Experts,

I am running COMPHEP for the following process:
qqbar->e*e->e,E,E,e
i.e. e* decaying to 3 leptons via contact interaction.

Just as a check I tried running for:
u+U->e,E,E,e

(1) I got two feynman diagrams.
Please find attached feynmanDiag.png
I understand that these two diagrams correspond to
e*+ in one and e*- in the other.
Do you think this is correct?


(2) The kinematic scheme showed by COMPHEP (also attached: kinematic_scheme.png) is as follows:
u,U->e,e,E,E
=========================================================
in=12   -> out1=3  out2 =456
in=456 -> out1=4  out2=56
in=56  ->  out1=5  out2=6
=========================================================
I am not sure about how the naming of the particles is done.
I understand that 456 always refer to the particles coming out from e* and 3 refers to the
one which is produced in conjunction with e*.
This scheme is valid for both the feynam diagrams
Do you think this understanding is correct?


(3) After putting Itmax=10 ; ncalls = 9720,
Please find the result of numerical calculation attached (please find comphepNumericalSession.ng attached).
The final xsec is: 3.035e-3 with an error of 4.59e-1. Is this error in %?  So the final error is
4.59e-1 times 3.035e-3?

Do you think the results are fine?

(4) I get the following distributions for E4, M456 (please find pt4.png and M456.png attached)
I see that:
(a) cross-section is increasing with E4. Shouldn't it start decreasing after some point?
(b) M456 should have peaked at 400 since I understand that 456 are coming from the decay of e*.
It is peaking but it is not sharply peaked.

All these distributions are done for pT of the outgoing particles > 15 GeV
and |eta| < 3.1

Do you think something is wrong going here?

Please let me know if you require more input from my side.

Thanks for your help,
Best Regards,
Shilpi Jain

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