The VINCIA code is a plugin to the high-energy physics
It is based on the dipole-antenna picture of Quantum Chromodynamics
(QCD) and focusses on
describing jets and jet substructure with high precision.
The current version includes both initial- and final-state
showers, with some limitations; decays of coloured resonances (eg
top) are not yet handled, nor are any non-QCD shower branchings included.
LO matrix elements can be incorporated in the
evolution, as process-dependent 2→n antenna functions.
In hard parts of phase space, these
functions generate matrix-element
corrections to the shower. In soft parts, they should
improve the logarithmic accuracy of it, via unitarity.
The remaining perturbative uncertainties are estimated by systematic (and automated)
variations of scales, shower functions, evolution variables, etc.
In the automated mode, a vector
of output weights is produced for each event, the central value of
which is unity (for an ordinary unweighted event sample),
with the uncertainty variations
spreading out around it. The calculation is significantly faster than generating N
separate samples, and there is only one event sample to analyse, pass through detector
When activated, VINCIA replaces the internal PYTHIA parton
is performed as usual in PYTHIA, with the Lund string fragmentation
model. Instead of the PYTHIA initialisation step in the main program
the same function is called on the VINCIA object.
VINCIA modifies the input cross section for some processes; see
examples/vincia24.cc on how to take this into
Apart from that, the events are generated and analysed as in a normal
PYTHIA 8 run.
In addition, runtime displays with plots updated in realtime can be
created using the VINCIAROOT