decaying tops for aMC@NLO processes

Hi,

tt~h was one of the example that we present in the MadSpin paper.
So it is certainly working with full spin correlation.
It is the first paper where that process was done with full spin correlation and the conclusion was that the spin-correlation was more important that going to NLO accuracy.

Therefore, I would certainly not recommend to use “set spinmode none” in that case.

What is the error?

Cheers,

Olivier

> On Nov 7, 2016, at 11:42, Shankha Banerjee <email address hidden> wrote:
>
> New question #403859 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/403859
>
> Dear experts,
>
> I am trying to generate the following process :
>
> generate p p > t t~ h [QCD]
>
> and then decay these particles in the madspin card using
>
> decay t > w+ b, w+ > l+ vl
> decay t~ > w- b~, w- > l- vl~
> decay h > b b~
>
> If I don't write :
>
> set spinmode none
>
> then I am getting an error and the decay isn't working. If I keep this line then everything works fine.
>
> Can you please confirm that we can not perform the top decays otherwise? That is isn't there a way to keep the spin correlations intact for the top decay products?
>
> Thank you very much for your time.
>
> Best regards,
>
> Shankha.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Dear Olivier,

Thank you very much.

The error is this :

***************************************************************************************************************************
INFO: (1) Only a succession of 2 body decay are currently allowed
************************************************************
* *
* W E L C O M E to M A D S P I N *
* *
************************************************************
INFO: Extracting the banner ...
INFO: process: p p > t t~ h
INFO: options:
INFO: detected model: loop_sm. Loading...
set max_weight_ps_point 400 # number of PS to estimate the maximum for each event
decay t > w+ b, w+ > l+ vl
decay t~ > w- b~, w- > l- vl~
decay h > b b~
launch
INFO: Will use seed 637106503
INFO: generating Madspin matrix element
WARNING: set the mass of the b-quark to its value in the param_card.dat: 4.7 GeV
INFO: We need to recalculate the branching fractions for t~,h,w-,w+,t
INFO: Using MadWidth (arXiv:1402.1178)
INFO: Restrict model /home/shankha/Packages_new/new_mg2/MG5_aMC_v2_3_3/models/loop_sm with file ../models/loop_sm/restrict_default.dat .
INFO: Run "set stdout_level DEBUG" before import for more information.
WARNING: The LO estimate for the width of particle 25
WARNING: differs from the one in the banner by 12 percent
INFO:
INFO: decay channels for t~ : ( width = 1.4969 GeV )
INFO: BR d1 d2
INFO: 1.000000e+00 b~ w-
INFO:
INFO:
INFO: decay channels for h : ( width = 0.00564964 GeV )
INFO: BR d1 d2
INFO: 9.542024e-01 b~ b
INFO: 4.579761e-02 ta+ ta-
INFO:
INFO:
INFO: decay channels for w- : ( width = 2.00291 GeV )
INFO: BR d1 d2
INFO: 3.333650e-01 d u~
INFO: 3.333650e-01 s c~
INFO: 1.111183e-01 e- ve~
INFO: 1.111183e-01 mu- vm~
INFO: 1.110334e-01 ta- vt~
INFO:
INFO:
INFO: decay channels for w+ : ( width = 2.00291 GeV )
INFO: BR d1 d2
INFO: 3.333650e-01 d~ u
INFO: 3.333650e-01 s~ c
INFO: 1.111183e-01 e+ ve
INFO: 1.111183e-01 mu+ vm
INFO: 1.110334e-01 ta+ vt
INFO:
INFO:
INFO: decay channels for t : ( width = 1.4969 GeV )
INFO: BR d1 d2
INFO: 1.000000e+00 b w+
INFO:
INFO: generating the production square matrix element
INFO: generate p p > t t~ h --no_warning=duplicate;define pert_ QCD = ;add process p p > t t~ h pert_ QCD --no_warning=duplicate;
Command "define pert_ QCD = " interrupted in sub-command:
"define pert_ QCD =" with error:
InvalidCmd : "define" command requires symbols "=" at the second position
Command "add process p p > t t~ h pert_ QCD --no_warning=duplicate" interrupted with error:
InvalidCmd : No particle pert_ in model
INFO: Done 1.42
INFO: generating the full square matrix element (with decay)
INFO: generate p p > t t~ h , (t~ > b~ w- , w- > l- vl~ QCD=99), h > b b~ QCD=99, (t > b w+ , w+ > l+ vl QCD=99) --no_warning=duplicate;define pert_ QCD = ;add process p p > t t~ h pert_ QCD, (t~ > b~ w- , w- > l- vl~ QCD=99), h > b b~ QCD=99, (t > b w+ , w+ > l+ vl QCD=99) --no_warning=duplicate;
Command "define pert_ QCD = " interrupted in sub-command:
"define pert_ QCD =" with error:
InvalidCmd : "define" command requires symbols "=" at the second position
Command "add process p p > t t~ h pert_ QCD, (t~ > b~ w- , w- > l- vl~ QCD=99), h > b b~ QCD=99, (t > b w+ , w+ > l+ vl QCD=99) --no_warning=duplicate" interrupted with error:
InvalidCmd : No particle pert_ in model
INFO: Done 2.144
INFO: generate matrix element for decay only (1 - > N).
INFO: output standalone_msF /home/shankha/Packages_new/new_mg2/MG5_aMC_v2_3_3/tth/pp2tth_NLO_decay/decay_me
INFO: Done 1.069
INFO: Compiling code
INFO: running MadSpin
INFO: detect independant decays
INFO: Done in 0.0660598278046s
INFO: MadSpin: Estimate the maximum weight
INFO:
INFO: Estimating the maximum weight
INFO: *****************************
INFO: Probing the first 75 events
INFO: with 400 phase space points
INFO:
INFO: Event 1/75 : 0.17s
Command "launch auto " interrupted with error:
KeyError : ((21, 21), (-6, 6, 21, 25))
Please report this bug on https://bugs.launchpad.net/madgraph5
More information is found in '/home/shankha/Packages_new/new_mg2/MG5_aMC_v2_3_3/tth/pp2tth_NLO_decay/run_01_tag_1_debug.log'.
Please attach this file to your report.
INFO:

quit
INFO:
************************************************************************************************************************

I am using the loop_sm model and generating like this :

generate p p > t t~ h [QCD]

Then in the MadSpin card, I am just doing :

decay t > w+ b, w+ > l+ vl
decay t~ > w- b~, w- > l- vl~
decay h > b b~

Then the process runs and crashes when it tries MadSpin. I am using MadGraph_aMC@NLO version 2.3.3.

Am I missing something essential?

Thank you very much once again.

Best regards,

Shankha.

Dear Olivier,

Thank you very much. You are right, the problem was due to a parser. I redid the run by correctly checking that there are no spaces before "QCD" and it worked like a charm.

Thank you very much for your time.

Best regards,

Shankha.

Thanks Olivier Mattelaer, that solved my question.

Hi,

I'm still puzzled by this, since I check the parser in 2.3.3 and it should remove the space correctly if you do
[ QCD] or [ QCD ]
Can you check which syntax you where using before such that I can ensure that such syntax is correctly handle in the next version of the code?

CHeers,

Olivier