<chapter name="VINCIA QED Antenna Shower Settings"> 
<h2>VINCIA QED Antenna Shower Settings</h2> 
 
<p>Here, parameters specific to VINCIA's QED antenna 
shower are collected. See the <aidx href="Vincia">main VINCIA 
antenna shower page</aidx> for more general parameters that are 
common to both the QCD and QED showers. 
</p> 
 
<h3>Main Switches</h3> 
 
<flag name="Vincia:doQED" default="on"> 
Main switch for QED evolution on/off. 
</flag> 
 
<modepick name="Vincia:nGammaToQuark" default="5" min="0" max="6"> 
Number of allowed quark flavours in final-state photon splitting. 
</modepick> 
 
<modepick name="Vincia:nGammaToLepton" default="3" min="0" max="3"> 
Number of allowed lepton flavours in final-state photon splitting. 
</modepick> 
 
<flag name="Vincia:convertGammaToQuark" default="on"> 
Allow incoming photons to backwards-evolve into (anti)quarks during the 
initial-state shower evolution. 
</flag> 
 
<flag name="Vincia:convertQuarkToGamma" default="on"> 
Allow incoming (anti)quarks to backwards-evolve into photons during the 
initial-state shower evolution. 
</flag> 
 
 
<h3>The QED coupling in the Vincia Shower</h3> 
<modepick name="Vincia:alphaEMorder" default="1" min="0" max="1"> 
<option value="0">zeroth order, i.e. <ei>&alpha;<sub>em</sub></ei> is kept 
fixed. 
</option> 
<option value="1">first order, i.e., one-loop running. 
</option> 
</modepick> 
 
<parm name="Vincia:alphaEM0" default="0.00729735" 
min="0.0072973" max="0.0072974"> 
The <ei>alpha_em</ei> value at vanishing momentum transfer 
(and also below <ei>m_e</ei>). 
</parm> 
 
<parm name="Vincia:alphaEMmZ" default="0.00781751" 
min="0.00780" max="0.00783"> 
The <ei>alpha_em</ei> value at the <ei>M_Z</ei> mass scale. 
</parm> 
 
<h3>Lower Cutoffs for the QED evolution</h3> 
<parm name="Vincia:QminChgQ" default="0.5" min="0.1" max="2.0"> 
Parton shower cut-off scale for photon coupling to coloured particle. 
</parm> 
 
<parm name="Vincia:QminChgL" default="1e-6" min="1e-10" max="2.0"> 
Parton shower cut-off scale for pure QED branchings. Assumed smaller than 
(or equal to) QminChgQ. 
</parm> 
 
<h3>Other QED Settings</h3> 
<modepick name="Vincia:photonEmissionMode" default="1" min="1" max="2"> 
<option value = "1">Pairing algorithm</option> 
<option value = "2">Coherent algorithm</option> 
</modepick> 
 
<flag name="Vincia:fullWkernel" default="on"> 
Switch to incorporate the full antenna function for W radiation. If disabled, 
a W radiates as if it were a lepton. 
</flag> 
 
<parm name="Vincia:mMaxGamma" default="10." min="0.001" max="5000.0"> 
Maximum invariant mass allowed for the created fermion pair by photon 
splitting in the shower. 
</parm> 
 
</chapter> 
