generation of p p > w+ w- j > e+ ve w- ve~ j at NLO

Hi,

I guess that the command that you search for is

generate p p > W+ W- > e+ ve e- ve~ j [QCD]

Indeed Fixed order and MadSpin can not be run together since MadSpin needs to have as input some events and we do not generate events for Fixed order (since they are not physical in the sense that they can not be showered).

Cheers,

Olivier

On 03 May 2015, at 17:26, Tania Robens <email address hidden> wrote:

> New question #266361 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/266361
>
> hi -
>
> i want to generate the above process and run it at fixed order. i have tried the following:
>
> - generate p p > w+ w- j > e+ ve w- ve~ j [QCD]
>
> and get
>
> Command "generate p p > W+ W- j > e+ ve e- ve~ j [QCD]" interrupted with error:
> InvalidCmd : Born diagrams could not be generated for the process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > w+ w- g u c d s u~ c~ d~ s~> e+ ve e- ve~ g/u/c/d/s/u~/c~/d~/s~ WEIGHTED=26 [ all = QCD ]. Notice that aMC@NLO does not handle loop-induced processes yet, but you can still use MadLoop if you want to only generate them. For this, use the 'virt=' mode, without multiparticle labels.
> (this was tested also w the latest version, 2.2.3, which i downloaded < 2 mins ago from launchpad)
>
>
> (even at tree level this does not work;
>
>
> generate p p > w+ w- j > e+ ve e- ve~ j
> Command "generate p p > w+ w- j > e+ ve e- ve~ j" interrupted with error:
> InvalidCmd : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > w+ w- g u c d s u~ c~ d~ s~> e+ ve e- ve~ g/u/c/d/s/u~/c~/d~/s~ WEIGHTED=26. Please enter a valid process
>
> i guess its a matter of number of particles in the intermediate state ??!
>
> )
>
>
> an alternative i tried is
>
> -generate p p > w+ w- j, w+ > e+ ve, w- > mu- vm~ [QCD]
>
> Error detected in "generate p p > w+ w- j, w+ > e+ ve, w- > mu- vm~ [QCD]"
> write debug file MG5_debug
> If you need help with this issue please contact us on https://answers.launchpad.net/madgraph5
> MadGraph5Error : Decay processes cannot be perturbed
>
>
>
> and third
>
> generate p p > w+ w- j [QCD]
>
> but in this case, switching either madspin or fixed order on seem to be mutually exclusive:
>
>
> The following switches determine which operations are executed:
> 1 Perturbative order of the calculation: order=NLO
> 2 Fixed order (no event generation and no MC@[N]LO matching): fixed_order=OFF
> 3 Shower the generated events: shower=ON
> 4 Decay particles with the MadSpin module: madspin=ON
> Either type the switch number (1 to 4) to change its default setting,
> or set any switch explicitly (e.g. type 'order=LO' at the prompt)
> Type '0', 'auto', 'done' or just press enter when you are done.
> [0, 1, 2, 3, 4, auto, done, order=LO, order=NLO, ... ][60s to answer]
>> 2
> INFO: For coherence 'shower' is set to 'OFF'
> INFO: For coherence 'madspin' is set to 'OFF'
> The following switches determine which operations are executed:
> 1 Perturbative order of the calculation: order=NLO
> 2 Fixed order (no event generation and no MC@[N]LO matching): fixed_order=ON
> 3 Shower the generated events: shower=OFF
> 4 Decay particles with the MadSpin module: madspin=OFF
> Either type the switch number (1 to 4) to change its default setting,
> or set any switch explicitly (e.g. type 'order=LO' at the prompt)
> Type '0', 'auto', 'done' or just press enter when you are done.
> [0, 1, 2, 3, 4, auto, done, order=LO, order=NLO, ... ][60s to answer]
>> 4
> INFO: For coherence 'fixed_order' is set to 'OFF'
>
>
>
>
> obviously pp> e+ ve w- ve~ j [QCD] works fine, but i have additional diagrams (most of which will probably be highly suppressed as they involve e.g. higly offshell nu, e -> w+..., but still...)
>
> therefore, is there any way to generate that process and specify the decay, keeping it at fixed order, other than imposing cuts around m_{enu} ?? :-) i dont care about on or offshell ws
>
> thanks best tania
>
>
>
> --
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> contact for MadGraph5_aMC@NLO.

looks good, thanks :-)