Invariant mass cut for three photon

Asked by Ribella

Dear Authors,

How can I put the invariant mass cut (m_aaa) for the three photons in the final state for process pp->aaa? Also, can I apply cut at parton level for each photon separately? (Et_a1, Et_a2,Et_a3).

Best Regards.

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Olivier Mattelaer (olivier-mattelaer) said :

For your process you should be able to use dsqrt_shat.
Note that this is a quite recent cut, so you need recent version of the code to have access to it.
In particular, such cut is not part of the Long Term Stable release (was implemented after that LTS was in bug only fixing mode).

If I'm correct you need at least 3.3.0 to have that cut available.

> Also, can I apply cut at parton level for each photon separately? (Et_a1, Et_a2,Et_a3).

We do not have such kind of cut available, so the options are
- implement those cuts as post-processing
- hard code such cuts in the dummy_functions.f (which has a function ready for user custom cuts)
Note that the phase-space integrator will not be pre-optimised for custom cuts and therefore it is possible that the phase-space integrator does not behave correctly (zero cross-section for all channel or, worse, for some channel only) so if you use that way please do plenty of validation and check that you do not have any channel of integration that returns zero (and if some does be sure that you understand why)



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Ribella (ribella) said :

Thanks Olivier, that solved my question.