CalcHEP

Negative total cross section

Asked by Heurtier

I am dealing with a model containing one pseudo scalar and neutrinos (R-handed and left handed) interacting together.

Computing the process

\nu_R \nu_R -> \nu_L \nu_L + \nu_R\nu_R -> \nu_L \nu_R through the exchange (s-channel and t-channel) of the pseudo scalar, I use the mathematica notebook sum_int.m to compute the total cross section.

For some values of the energy scale s I get negative cross section...

any Idea of where it could come from?

Best

Lucien

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Alexander Pukhov (pukhov) said : 		#1

It should not be so. More likely your Lagrangian is not Hermitian.
If gauge invariance is lost, then CalcHEP sometimes produces negative cross section for processes with vector gauge bosons.
It seems, it is not your case. Send me your model and the process. I'll check.

Best
    Alexander Pukhov

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Alexander Belyaev (alexander.belyaev) said : 		#3

Please let us know if you still have the problem

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