Rivet analyses

title: ALICE_2015_CENT_PPB

ALICE proton-lead centrality calibration analysis.

Experiment: ()

Status: UNVALIDATED

Authors: - Christian Bierlich

References: - Phys.Lett.B728(2014)25-38,arXiv:1307.6796

Beams: * *

Beam energies: ANY

Run details: - Any!

Calibration analysis for ALICE pPb centrality. The centrality measure is multiplicity in VO-A ie. in the lead direction. No reference data is given, as the spectrum is not possible to unfold.

Source code:ALICE_2015_CENT_PPB.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Analyses/AliceCommon.hh"

include "Rivet/Projections/ImpactParameterProjection.hh"

namespace Rivet {

/// Generic analysis looking at various distributions of final state particles class ALICE_2015_CENT_PPB : public Analysis {

public:

RIVET_DEFAULT_ANALYSIS_CTOR(ALICE_2015_CENT_PPB);

/// Book histograms and initialise projections before the run
void init() {

  // One projection for the actual observable, and one for the
  // generated impact parameter.
  declare(ALICE::V0AMultiplicity(), "V0A");
  declare(ImpactParameterProjection(), "IMP");
  declare(ALICE::V0AndTrigger(), "Trigger");

  // The calibration histogram:
  book(_calib, "V0A", 100, 0.0, 500.0);


  // The alternative histogram based on impact parameter. Note that
  // it MUST be named the same as the histogram for the experimental
  // observable with an added _IMP suffix.
  book(_impcalib, "V0A_IMP", 400, 0.0, 20.0);
}

/// Perform the per-event analysis
void analyze(const Event& event) {

  // The alternative centrality based on generated impact
  // parameter, assumes that the generator does not describe the
  // full final state, and should therefore be filled even if the
  // event is not triggered.
  _impcalib->fill(apply<SingleValueProjection>(event, "IMP")());

  if (!apply<ALICE::V0AndTrigger>(event, "Trigger")()) vetoEvent;

  _calib->fill(apply<ALICE::V0AMultiplicity>(event, "V0A")());
}


/// Finalize
void finalize() {

  _calib->normalize();
  _impcalib->normalize();
}

private:

/// The calibration histograms.
Histo1DPtr _calib;
Histo1DPtr _impcalib;

};

RIVET_DECLARE_PLUGIN(ALICE_2015_CENT_PPB);

} ```