# Meaning of various parameters in the run_card.dat

Created by Olivier Mattelaer
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Olivier Mattelaer

Most of the parameter in the run_card.dat are self explanatory but some of them are not.

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** run_tag

This is a name in order to distinguish the various post-processing run (pythia-pgs-Delphes) that you can perform after running the event generation. This tag will appear in the html output and some of the output file will start by this string. (so no physics inside this parameter)

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** gridpack

This activates a special mode of running, where the purpose is to create a code which produces the full physical distributions on a single core. This options is convenient if you need to use the grid for the generation since this allows paralyzation but each jobs is fully independent (contrary to standard cluster mode where if one job fails the total distributions is not physical anymore). For more information about this mode, you can read: https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/IntroGrid

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** bwcutoff
The run_card parameter bwcutoff defines what is considered to be on-shell s-channel resonances: The resonance if considered to be on-shell if the invariant mass of an s-channel resonance is within M +/- bwcutoff*Gamma, and will then be included as a comment particle in the LHE event file (with status code 2). The value of bwcutoff does not affect the cross section of any processes, except if
1) you use the decay chain formalism: [a b > c d , c > e f, d > g h] Decay chain processes are strictly valid only in the narrow width limit, and we have therefore chosen to allow only production of on-shell particles. This means that the cross section will get smaller as bwcutoff gets smaller, since more of the tails of the Breit Wigner distributions are cut off.
2) If you forbid s-channel particles to be on shell ($symbol)[a b> e f g h$ c d]. This is the exact complementary of the previous case. Where the a b > c d , c > e f, d > g h is not contributing of the mass of the c or the d is on-shell (i,e again M +/- bwcutoff*Gamma).

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** ickkw

Those are parameters which are useful in order to avoid double counting between to multiplicity sample
(like p p > W+ j and p p > W+ j j). Indeed the shower mixes the multiplicity and therefore induce a double counting which needs to be taken out. For more details, please read: https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/IntroMatching

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** xqcut

xqcut defines the minimal distance between partons at the matrix-element level (in K_T measure). This is an important cut for the matching

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** fixed_ren_scale and fixed_fac_scale

The default way to compute the scale is explained here:

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** cut_decays

Allow to control cut for decay product.
it allow to turn on/off the following cut: pt/E/eta/dr/mij cuts on decay products or not.
A decay product is a particle which origins from a decay in the decay syntax chain.
For example:
p p > Z j j , Z > b b~
The b/b~ are consider as decay product but not the "j".

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** WBF cut (xetamin and deltaeta)

-The xetamin cut is applied on the two hardest jets and ensures that
*the eta of each jet is larger then xetamin
*the eta signs are different (to make sure they are oriented to two different longitudinal directions)

-The DeltaEta is also applied on the two hardest jets, and ensures that
* the eta difference between the two hardest jets rapidities is larger than deltaeta.
* the eta signs are different (to make sure they are oriented to two different longitudinal directions)

Both cuts give a slightly different description of how to select VBF cuts.

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** dynamical_scale_choice (new in 2.3)

-1 : MadGraph5_aMC@NLO default (different for LO/NLO/ ickkw mode) same as previous version.
0 : Tag reserved for user define dynamical scale (need to be added in setscales.f).
1 : Total transverse energy of the event.
2 : sum of the transverse mass
3 : sum of the transverse mass divide by 2
4 : \sqrt(s), partonic energy (only for LO run)