Changes between Initial Version and Version 1 of DevelopmentPage/Clustering

Timestamp:

Jan 22, 2014, 11:28:47 AM (11 years ago)

Author:

Olivier Mattelaer

Comment:

--

DevelopmentPage/Clustering

@@ +1 @@
+= Clustering/reweighting page
+
+== OBJECT MEANING
+
+*** WARNING *** THIS IS ONLY MY CURRENT UNDERSTANDING OF JOHAN's CODE. IT MIGHT BE ... WRONG
+
+=== idacl(NEXTERNAL,2)
+
+Returns an id identifying uniquely a particles:
+For an external particles the id is $2^(N-1)$. For a propagator this is the sum of the id of all particles in which 
+this particles decays.
+
+The first index indicates the various merging steps and the second index which particles is merging with wich ones.
+
+=== icluster(4,nexternal)
+
+Not clear, the code comment says:
+c     variable for LH output of clustering info (R,E,S,I)
+but no idea what those four letter means...
+
+=== imocl(NEXTERNAL)
+
+Returns an id identifying uniquely a particles associated to the merging of that level.
+we therefore have idacl(I,1) + idacl(I,2) -> imocl(I)
+
+=== iproc
+
+I guess that's refer to the which matrix.f we have to consider for the graph.
+
+=== igraphs(0:n_max_cg)
+
+The first component is special (syze for the specific process?)
+I guess that this is the link to the various diagrams (in the various matrix.f) for the specific config.
+
+=== ipart(2,n_max_cl)
+
+   ipart gives the external particle number corresponding to the present 
+   quark or gluon line.           
+   For t-channel lines, ipart(1) contains the connected beam.
+   For s-channel lines, it depends if it is quark or gluon line:
+   For quark lines, ipart(2) is 0 and ipart(1) connects to the corresponding
+   final-state quark. For gluons, if it splits into two gluons,
+   it connects to the hardest gluon. If it splits into qqbar, it ipart(1) is 
+   the hardest and ipart(2) is the softest.
+
+=== other comment/variable
+      1.  jfirst(2) is first parton splitting on this side
+      1.  jlast(2) is last parton on this side
+      1.  jcentral(2) is the central scale vertex on this side
+      1.  qcdline(2) gives whether this IS line is QCD
+      1.  partonline(2) gives whether this IS line is parton (start out true for any QCD)
+      1.  goodjet(n_max_cl) gives whether this cluster line is considered a jet 
+      1.  jcode helps keep track of how many QCD/non-QCD flips we have gone through
+      1.  increasecode gives whether we should increase jcode at next vertex 
+
+
+=== clustering technique
+
+  1. The last step of the clustering is (always?) the one with ipart(1, X) and ipart(2,X) are [1,2]!
+  1.