Hi,

I actually learned something today, indeed this cut is present in 2.3.3.
I will discuss with Valentin Hirschi and Stepan Pretzel to see what change they did to that cut when they 
add the official support of CKKW-L in 2.5.0.

Cheers,

Olivier


> On Nov 30, 2017, at 13:15, Emma Kuwertz <email address hidden> wrote:
> 
> Dear Olivier,
> 
> thanks for your reply and for your checks. I tried to replicate your
> test in 2.6.0 and 2.3.3, but this time included a cut on ktdurham (as is
> used in our setup).
> 
> I ran the following:
> import model mssm
> generate p p > go go
> add process p p > go go j
> output -f
> launch
> set ickkw 0
> set xqcut 0
> set mgo 1000
> set ktdurham 250
> 
> It looks as though you have been able to set ktdurham since 2.0.0, which
> we understood is needed for CKKW-L merging?
> 
> The results we get are as follows:
> 
> 2.6.0
> cross-section 0.2005 pm 0.000402 pb
> 
> 2.3.3
> cross-section 0.19147 pm 0.000345 pb
> 
> Here the p2 cross-sections increase by 50% in 2.3.3 wrt 2.6.0.
> 
> We didn't make any hack to 2.3.3 in order to deal with CKKW-L merging,
> we understood that the configuration should work as is.  I guess the
> question is did the behaviour of the ktdurham variable change
> significantly between 2.3.3 and 2.6.0?
> 
> Thanks,
> Emma & Zach
> 
> -- 
> You received this bug notification because you are subscribed to
> MadGraph5_aMC@NLO.
> https://bugs.launchpad.net/bugs/1731086
> 
> Title:
>  Change in production xsecs in SUSY models in 2.6.0
> 
> Status in MadGraph5_aMC@NLO:
>  New
> 
> Bug description:
>  Hi there,
> 
>  I'm hoping that you can help us track this issue down, as it's holding
>  up our validation of MadGraph 2.6.0.  Emma Kuwertz and I found that
>  between older and newer MadGraph releases, the cross section of p p >
>  go go j processes changed by 50% or more.  I set up and run out of the
>  box:
> 
>  import model mssm
>  generate p p > go go
>  add process p p > go go j
>  output -f
> 
>  in MadGraph 2.3.3 and 2.4.3.  I run the same in MadGraph 2.6.0, but
>  with `import model MSSM_SLHA2`.  In both releases I then set the
>  masses of all SUSY particles to be 10**9 GeV, except the gluino which
>  is set to 1 TeV.  All other parameters I leave as they are, out of the
>  box, but a quick check suggests that there aren't wild new cuts that
>  have appeared.  With 2.3.3 the cross section I get is:
> 
>       Cross-section :   0.662 +- 0.00212 pb
> 
>  With 2.4.3 and 2.6.0, I get the same answer:
> 
>       Cross-section :   0.7888 +- 0.002181 pb
> 
>  There, the cross section files suggest that most of the difference is
>  due to a large (>25%) change in g g > go go g.  I don't see any
>  difference in the PDFs that might cause such a change, though.
> 
>  In Emma's run inside the ATLAS framework, we were looking at more
>  modest total cross section changes, but large changes to the go go j
>  cross section (of order 50%) that led to significantly harder
>  kinematics in one case than the other.
> 
>  Is there some known feature of the releases that would have caused
>  these differences?  I tried to look over the update notes, but I
>  didn't find anything sinister.
> 
> 
>  Thanks,
>  Zach
> 
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