EW V + jets NLO

Asked by negin on 2018-06-26

Dear authors,

Is amC@NLO well suited for calculating EW V + jj with NLO corrections ?

with aMC v254 I ran
generate p p > z j j QCD=0 [QCD]

using
  1.0 = jetalgo ! FastJet jet algorithm (1=kT, 0=C/A, -1=anti-kT)
  0.4 = jetradius ! The radius parameter for the jet algorithm
20.0 = ptj ! Min jet transverse momentum
  5.0 = etaj ! Max jet abs(pseudo-rap) (a value .lt.0 means no cut)

and got
aMCatNLOError: Poles do not cancel, run cannot continue

Could you kindly let me know how I should proceed, if possible ?

Best Regards

Question information

Language:
English Edit question
Status:
Open
For:
MadGraph5_aMC@NLO Edit question
Assignee:
marco zaro Edit question
Last query:
2 hours ago
Last reply:
2018-06-26

This question was reopened

marco zaro (marco-zaro) said : #1

Hi,
you can generate EW Z-production plus two jets at NLO QCD in two ways:
- with the standard (2.6.x) branch, you will not generate loop diagrams featuring EW bosons, and you have to turn off the check poles.
You can find the details (and how to turn them off) e.g. in this paper, where VBS has been studied
https://arxiv.org/pdf/1803.07943.pdf
- with the new, EW-capable branch (3.0.x), you can compute the full thing but only at fixed order (no event genration, no shower), because some corrections stem from EW corrections on top of the alpha^2 alpha_s interference. I fear you need to decay the Z in that case, I would advise you to start with the first option, which should normally be good enough.

Let us know
Cheers,

Marco

negin (neginsh) said : #2

Thanks marco zaro, that solved my question.

negin (neginsh) said : #3

Hi ,
thanks for your respond , I have tried that way and it worked but still one problem, I have large differences in cross-section of NLO and LO. I think 51.80 pb is large for NLO corrections as for LO is 37.42 pb! what do you think?

Cheers
Negin

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