<chapter name="Dire Expert Settings"> 
 
<h2>Dire Expert Settings</h2> 
 
One purpose of Dire is to have a numerical tool that can be compared to 
analytic resummation techniques as well as possible. Thus, some settings 
are available to facilitate theory comparisons. In an experimental 
production run, these paramaters should not be changed from their default 
values. 
 
 
<h3>Further QCD and QED photon shower settings</h3> 
 
<flag name="Dire:QED:doForcePosChgCorrelators" default="off"> 
If on, this requires all QED splitting functions to use positive charge 
correlators. This especially means that some (otherwise in principle allowed) 
splittings are forbidden. This switch is only included to compare to other 
methods. 
</flag> 
 
<parm name="Dire:QED:pTminForcePos" default="-1.0"> 
This parameter determines the minimal evolution variable above which the above 
scheme of positive-only charge correlators is employed. 
</parm> 
 
On top of possible scaling factors for the arguments of the running QCD 
coupling, Dire also offers different functional forms of the argument itself. 
All of these functional forms reduce to a relative transverse momentum in 
the soft collinear limits, but differ for hard emissions. 
 
<modepick name="DireTimes:alphasScheme" default="0"> 
<option value="0"> 
The evolution variable is used as argument of the strong coupling. 
</option> 
<option value="1"> 
The collinear transverse momentum is used as argument. 
</option> 
<option value="2"> 
The eikonal factor <ei>sij sjk / sik</ei> for the splitting 
<ei>(ij),k -> i,j,k</ei> is used. 
</option> 
</modepick> 
 
<modepick name="DireSpace:alphasScheme" default="0"> 
<option value="0"> 
The evolution variable is used as argument of the strong coupling. 
</option> 
<option value="1"> 
The collinear transverse momentum is used as argument. 
</option> 
<option value="2"> 
The eikonal factor <ei>sij sjk / sik</ei> for the splitting 
<ei>(ij),k -> i,j,k</ei> is used. 
</option> 
</modepick> 
 
 
 
<h3>Further dark photon shower settings</h3> 
 
Dark photon emissions/splittings in Dire can be enabled with the following 
switches. It is worth noting that dark-photon radiation is handled very 
similar to QED/QCD radiation. 
 
<flag name="TimeShower:U1newShowerByL" default="off"> 
If on, then final state leptons are allowed to radiate dark photons. 
</flag> 
 
<flag name="TimeShower:U1newShowerByQ" default="off"> 
If on, then final state quarks are allowed to radiate dark photons. 
</flag> 
 
<flag name="SpaceShower:U1newShowerByL" default="off"> 
If on, then incoming leptons are allowed to radiate dark photons. 
</flag> 
 
<flag name="SpaceShower:U1newShowerByQ" default="off"> 
If on, then incoming quarks are allowed to radiate dark photons. 
</flag> 
 
<p> 
Dark photon emission rates are govered by several parameters. 
</p> 
 
<parm name="Dire:U1new:alphaX" default="1.0"> 
The coupling of the dark photon to (ficticious) dark-sector particles. 
</parm> 
 
 
<h3>Matching and merging settings</h3> 
 
Dire offers some functionality for matrix-element + parton shower merging. 
The currently most advanced of the available schemes are iterated matrix 
element corrections in the "MOPS" scheme. The details of the scheme are 
goverened by the following settings. 
 
<flag name="Dire:doMECs" default="off"> 
If on, matrix-element corrections for the first few splittings are used. 
</flag> 
 
<word name="Dire:MG5card" default=""> 
The ME corrections in Dire rely on code produced by MadGraph5. The 
initialization of this code requires a Madgraph parameter card. This 
setting should give the full path to such a "<code>param_card</code>". 
Without this input, the code will abort. 
</word> 
 
<modeopen name="Dire:nFinalMaxMECs" default="-1"> 
If set, this limits the amount of matrix element corrections to final-state 
particle counts below this value. Any negative value means that ME corrections 
are applied for each splitting for which ME code is available. 
</modeopen> 
 
<parm name="Dire:pTminMECs" default="1.0"> 
The minimal evolution scale value (in GeV) for which ME corrections should 
be applied. A negative value means no restriction. 
</parm> 
 
<parm name="Dire:QminMECs" default="1.0"> 
The minimal of all two-particle momentum invariants (in GeV) for which ME 
corrections should be applied. Non-negative values mean that all two-particle 
invariants are calculated, and if any is below this parameter, then ME 
corrections are not attempted. The corresponding change in the emission rate 
is relected in the probability of clustering histories used for MECs, such 
that subsequent ME corrections still recover the correct distribution. 
</parm> 
 
<flag name="Dire:suppressLargeMECs" default="off"> 
</flag> 
 
<word name = "Dire:MEplugin" default = ""> 
  name of the plugin library to use for matrix element corrections. 
</word> 
 
<h3>Other experimental merging settings</h3> 
 
<p> 
The following settings are currently under investigation and not used 
in the code. 
</p> 
 
<flag name="Dire:doMerging" default="off"> 
This switch should be considered experimental. If on, this simply ensures 
that the merging machinery can be accessed. The type of merging can then 
be further specified with the switches below. 
</flag> 
 
<flag name="Dire:doMOPS" default="off"> 
This flag switches on the handling of unordered configurations necessary in 
the MOPS merging method. 
</flag> 
 
<flag name="Dire:doMEM" default="off"> 
This flag switches on the possibility to classify input configurations 
according to the HYTRESS hypothesis testing scheme. 
</flag> 
 
<parm name="MEM:WidthH" default="-1.0"> 
This parameter allows to set the Higgs-boson width parameter used to calculate 
Higgs hypothesis likelihoods in the HYTREES scheme. 
</parm> 
 
<flag name="Dire:doGenerateSubtractions" default="off"> 
This flag allows to retrieve differential real-emission parton-shower 
counter-terms necessary for MC@NLO matching directly from a shower 
call. 
</flag> 
 
<flag name="Dire:doGenerateMergingWeights" default="off"> 
This flag allows to switch on/off the generation of CKKW-L-type 
reweighting factors by the merging machinery. 
</flag> 
 
<flag name="Dire:doSingleLegSudakovs" default="off"> 
This flag allows to retrieve no-emission probabilities from the parton 
showers on a leg-by-leg basis. The default definition of no-emission 
probabilities is instead based on the evolution of a state as as a whole. 
</flag> 
 
<flag name="Dire:doExitAfterMerging" default="off"> 
If on, this switch will allow to terminate the event processing once 
the calls to the merging machinery have been executed. 
</flag> 
 
<flag name="DireTimes:DecaysAsShower" default="off"> 
If on, then shower-generated particles that are classified as resonances 
can also decayed directly within the final-state parton-shower evolution. 
</flag> 
 
<flag name="DireSpace:DecaysAsShower" default="off"> 
If on, then shower-generated particles that are classified as resonances 
can also decayed directly within the initial-state parton-shower evolution. 
</flag> 
 
 
<h3>Color factors</h3> 
 
The expert user may also want to change the color factors used by QCD 
showering. This can be done using the settings 
 
<parm name="DireColorQCD:TR" default="-1.0"> 
Changes TR used by Dire. Any negative value means that consistent defaults 
are used. 
</parm> 
 
<parm name="DireColorQCD:CA" default="-1.0"> 
Changes CA used by Dire. Any negative value means that consistent defaults 
are used. 
</parm> 
 
<parm name="DireColorQCD:NC" default="-1.0"> 
Changes NC used by Dire. Any negative value means that consistent defaults 
are used. 
</parm> 
 
<parm name="DireColorQCD:CF" default="-1.0"> 
Changes CF used by Dire. Any negative value means that consistent defaults 
are used. 
</parm> 
 
<h3>Configurable timelike splitting kernels</h3> 
 
For in-depth theory comparisons, changed splitting kernels can be necessary. 
Thus, the user can customize the  soft, collinear and finite behavior of 
timelike splitting probabilities to a large extent by changing the 
coefficients of mock-up series expansions and by exponential factors. 
A publication discussing these options is in preparation. 
 
<flag name="DireTimes:useBackboneGluons" default="off"> 
This flag ensures that the recoil in radiation off gluons that trace back 
to the core process is handled identical to that off hard-process quarks, as 
is relevant for theoretical quark-gluon discrimination studies. 
</flag> 
 
 
<flag name="DireTimes:doGeneralizedKernel" default="off"> 
If enabled, then the user may reconfigure timelike splitting kernels. 
</flag> 
 
<p> 
Please find below all changeable coefficients. 
</p> 
 
<pvec name="DireGeneralizedKernel:softCoeffs:Dire_fsr_qcd_1->1&21" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:softExps:Dire_fsr_qcd_1->1&21" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaCoeffs:Dire_fsr_qcd_1->1&21" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaExps:Dire_fsr_qcd_1->1&21" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collCoeffs:Dire_fsr_qcd_1->1&21" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collExps:Dire_fsr_qcd_1->1&21" default="{0.,0.,0.,0.}"> 
</pvec> 
<parm name="DireGeneralizedKernel:finCoeffs:Dire_fsr_qcd_1->1&21" default="-2.0"> 
</parm> 
 
<pvec name="DireGeneralizedKernel:softCoeffs:Dire_fsr_qcd_1->21&1" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:softExps:Dire_fsr_qcd_1->21&1" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaCoeffs:Dire_fsr_qcd_1->21&1" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaExps:Dire_fsr_qcd_1->21&1" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collCoeffs:Dire_fsr_qcd_1->21&1" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collExps:Dire_fsr_qcd_1->21&1" default="{0.,0.,0.,0.}"> 
</pvec> 
<parm name="DireGeneralizedKernel:finCoeffs:Dire_fsr_qcd_1->21&1" default="-2.0"> 
</parm> 
 
<pvec name="DireGeneralizedKernel:softCoeffs:Dire_fsr_qcd_21->21&21a" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:softExps:Dire_fsr_qcd_21->21&21a" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaCoeffs:Dire_fsr_qcd_21->21&21a" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaExps:Dire_fsr_qcd_21->21&21a" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collCoeffs:Dire_fsr_qcd_21->21&21a" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collExps:Dire_fsr_qcd_21->21&21a" default="{0.,0.,0.,0.}"> 
</pvec> 
<parm name="DireGeneralizedKernel:finCoeffs:Dire_fsr_qcd_21->21&21a" default="-2.0"> 
</parm> 
 
<pvec name="DireGeneralizedKernel:softCoeffs:Dire_fsr_qcd_21->21&21b" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:softExps:Dire_fsr_qcd_21->21&21b" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaCoeffs:Dire_fsr_qcd_21->21&21b" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:kappaExps:Dire_fsr_qcd_21->21&21b" default="{0.,0.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collCoeffs:Dire_fsr_qcd_21->21&21b" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collExps:Dire_fsr_qcd_21->21&21b" default="{0.,0.,0.,0.}"> 
</pvec> 
<parm name="DireGeneralizedKernel:finCoeffs:Dire_fsr_qcd_21->21&21b" default="-2.0"> 
</parm> 
 
<pvec name="DireGeneralizedKernel:collCoeffs:Dire_fsr_qcd_21->1&1a" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collExps:Dire_fsr_qcd_21->1&1a" default="{0.,0.,0.,0.}"> 
</pvec> 
<parm name="DireGeneralizedKernel:finCoeffs:Dire_fsr_qcd_21->1&1a" default="0.0"> 
</parm> 
 
<pvec name="DireGeneralizedKernel:collCoeffs:Dire_fsr_qcd_21->1&1b" default="{0.,1.,0.,0.}"> 
</pvec> 
<pvec name="DireGeneralizedKernel:collExps:Dire_fsr_qcd_21->1&1b" default="{0.,0.,0.,0.}"> 
</pvec> 
<parm name="DireGeneralizedKernel:finCoeffs:Dire_fsr_qcd_21->1&1b" default="0.0"> 
</parm> 
 
</chapter> 
 
<!-- Copyright (C) 2020 Stefan Prestel --> 
