The VinClu clustering map
The VinClu clustering map is a 3->2 clustering
map rather similar to that of the Arclus jet clustering algorithm.
Its principal advantage is that it
contains the exact inverses of the Vincia kinematics mappings, and
hence it can be used to "undo" branchings and/or reconstruct the exact
intermediate shower states from a given momentum configuration. The
clustering is invoked using:
-
void VinClu(int iMap, vector< Particle> pIn, int a, int r, int
b, vector< Particle>& pClu);
Here iMap
is the
index number of the kinematics map to be used (the numbering follows
kineMapType
), pIn
is a vector of
arbitrary size containing the state of particles to be clustered,
and the indices a
, r
, b
represent the 3 particles to be clustered in the backwards
reconstruction of AB->arb. pClu
is initially
set equal to p
. The reconstructed momenta of the parents, A
and B, are then stored in pClu[a]
and pClu[b]
, respectively, and
finally pClu[r]
is erased. (Note that this last step
may cause the indices of A and/or B
in pClu
to be different from
those of a and b in p
. For the most
common case, a
color-ordered clustering with r=a+1 and b=a+2,
the indices of A and B after the clustering will
be A=a and B=A+1.)