pythia8130 distributed with AliRoot

[u/mrichter/AliRoot.git] / PYTHIA8 / pythia8130 / include / BoseEinstein.h

diff --git a/PYTHIA8/pythia8130/include/BoseEinstein.h b/PYTHIA8/pythia8130/include/BoseEinstein.h
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+// Bose-Einstein.h is a part of the PYTHIA event generator.
+// Copyright (C) 2008 Torbjorn Sjostrand.
+// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
+// Please respect the MCnet Guidelines, see GUIDELINES for details.
+
+// This file contains the classes to handle Bose-Einstein effects.
+// BoseEinsteinHadron: simple working container for particle momenta.
+// BoseEinstein: main class to perform the task.
+
+#ifndef Pythia8_BoseEinstein_H
+#define Pythia8_BoseEinstein_H
+
+#include "Basics.h"
+#include "Event.h"
+#include "ParticleData.h"
+#include "PythiaStdlib.h"
+#include "Settings.h"
+
+namespace Pythia8 {
+ 
+//**************************************************************************
+ 
+// The BoseEinsteinHadron class is a simple container for studied hadrons.
+
+class BoseEinsteinHadron {
+
+public:
+
+  // Constructors. 
+  BoseEinsteinHadron() : id(0), iPos(0), p(0.), pShift(0.), pComp(0.), 
+    m2(0.) {}
+  BoseEinsteinHadron(int idIn,  int iPosIn, Vec4 pIn, double mIn) : 
+    id(idIn), iPos(iPosIn), p(pIn), pShift(0.), pComp(0.) {m2 = mIn*mIn;}
+
+  // Information on hadron - all public.
+  int    id, iPos;
+  Vec4   p, pShift, pComp;
+  double m2;
+
+};
+
+//**************************************************************************
+
+// The BoseEinstein class shifts the momenta of identical particles relative 
+// to each other, to simulate Bose-Einstein effects to some approximation.
+
+class BoseEinstein {
+
+public:
+
+  // Constructor. 
+  BoseEinstein() {}
+
+  // Find settings. Precalculate table used to find momentum shifts.
+  bool init(Info* infoPtrIn);
+
+  // Perform Bose-Einstein corrections on an event.
+  bool shiftEvent( Event& event); 
+
+private: 
+
+  // Constants: could only be changed in the code itself.
+  static const int    IDHADRON[9], ITABLE[9], NCOMPSTEP;
+  static const double STEPSIZE, Q2MIN, COMPRELERR, COMPFACMAX;
+
+  // Initialization data, read from Settings.
+  bool   doPion, doKaon, doEta;
+  double lambda, QRef;
+
+  // Pointer to various information on the generation.
+  Info* infoPtr;
+
+  // Table of momentum shifts for different hadron species.
+  int    nStep[4], nStep3[4], nStored[10];
+  double QRef2, QRef3, R2Ref, R2Ref2, R2Ref3, mHadron[9],
+         mPair[4], m2Pair[4], deltaQ[4], deltaQ3[4], maxQ[4], maxQ3[4];
+  double shift[4][200], shift3[4][200]; 
+
+  // Vector of hadrons to study.
+  vector<BoseEinsteinHadron> hadronBE;
+
+  // Calculate shift and (unnormalized) compensation for pair.
+  void shiftPair(int i1, int i2, int iHad);
+  
+};
+ 
+//**************************************************************************
+
+} // end namespace Pythia8
+
+#endif // Pythia8_BoseEinstein_H
+