GenericSubtractor is part of the fastjet-contrib project.

This contribution introduces the following pile-up subtraction tools:
  - GenericSubtractor : area-median shape subtraction
  - SafeAreaSubtractor: area-median jet 4-vector subtraction
  - SafeNpCSubtractor : neutral-proportional-to-charged jet 4-vector subtraction

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GenericSubtractor
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The GenericSubtractor class (see GenericSubtractor.hh) allows one to
subtract pile-up contamination from jet shapes as described in

   Pileup subtraction for jet shapes
   Gregory Soyez, Gavin P. Salam, Jihun Kim, Souvik Dutta, Matteo Cacciari. 
   arXiv:1211.2811 

The comments in GenericSubtractor.hh give a full description of how
the class works. The code example.cc illustrates how to use the class
in a simple case. It can be built and run using

    make example
   ./example < ../data/Pythia-Zp2jets-lhc-pileup-1ev.dat
 
The expected output can be found in example.ref

A more advanced example (shapes made up of several components) is
given in example_with_components.cc, which can be built and run with 

    make example_with_components
   ./example_with_components < ../data/Pythia-Zp2jets-lhc-pileup-1ev.dat

and compared to the expected output example_with_components.ref 

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Safe subtractors: SafeAreaSubtractor and SafeNpCSubtractor
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2 classes are introduced in SafeSubtractor.hh:

  SafeAreaSubtractor   area-median subtraction
  SafeNpCSubtractor    neutral-proportional-to-charge subtraction

Compared to the existing Subtractor in FastJet it as several key
differences:

  - for area-median subtraction, it allows to include the effect of
    particle masses (the \rho_m term in arXiv:1211.2811).

  - it allows to handle either full or CHS types of events (as
    discussed in arXiv:1404.7353).

  - We impose that the subtracted pt remains positive (or at least
    equal to the pt we can associate to the leading vertex). We
    further impose that the mass is positive (or at least equal to the
    mass we can associate to the leading vertex) (as discussed in
    arXiv:1404.7353).

See individual classes for detailed descriptions and example_safesub.cc
for usage.