1 | // Bose-Einstein.h is a part of the PYTHIA event generator. |
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2 | // Copyright (C) 2012 Torbjorn Sjostrand. |
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3 | // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details. |
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4 | // Please respect the MCnet Guidelines, see GUIDELINES for details. |
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5 | |
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6 | // This file contains the classes to handle Bose-Einstein effects. |
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7 | // BoseEinsteinHadron: simple working container for particle momenta. |
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8 | // BoseEinstein: main class to perform the task. |
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9 | |
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10 | #ifndef Pythia8_BoseEinstein_H |
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11 | #define Pythia8_BoseEinstein_H |
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12 | |
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13 | #include "Basics.h" |
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14 | #include "Event.h" |
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15 | #include "ParticleData.h" |
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16 | #include "PythiaStdlib.h" |
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17 | #include "Settings.h" |
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18 | |
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19 | namespace Pythia8 { |
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20 | |
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21 | //========================================================================== |
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22 | |
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23 | // The BoseEinsteinHadron class is a simple container for studied hadrons. |
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24 | |
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25 | class BoseEinsteinHadron { |
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26 | |
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27 | public: |
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28 | |
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29 | // Constructors. |
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30 | BoseEinsteinHadron() : id(0), iPos(0), p(0.), pShift(0.), pComp(0.), |
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31 | m2(0.) {} |
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32 | BoseEinsteinHadron(int idIn, int iPosIn, Vec4 pIn, double mIn) : |
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33 | id(idIn), iPos(iPosIn), p(pIn), pShift(0.), pComp(0.) {m2 = mIn*mIn;} |
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34 | |
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35 | // Information on hadron - all public. |
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36 | int id, iPos; |
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37 | Vec4 p, pShift, pComp; |
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38 | double m2; |
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39 | |
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40 | }; |
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41 | |
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42 | //========================================================================== |
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43 | |
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44 | // The BoseEinstein class shifts the momenta of identical particles relative |
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45 | // to each other, to simulate Bose-Einstein effects to some approximation. |
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46 | |
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47 | class BoseEinstein { |
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48 | |
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49 | public: |
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50 | |
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51 | // Constructor. |
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52 | BoseEinstein() {} |
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53 | |
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54 | // Find settings. Precalculate table used to find momentum shifts. |
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55 | bool init(Info* infoPtrIn, Settings& settings, ParticleData& particleData); |
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56 | |
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57 | // Perform Bose-Einstein corrections on an event. |
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58 | bool shiftEvent( Event& event); |
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59 | |
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60 | private: |
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61 | |
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62 | // Constants: could only be changed in the code itself. |
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63 | static const int IDHADRON[9], ITABLE[9], NCOMPSTEP; |
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64 | static const double STEPSIZE, Q2MIN, COMPRELERR, COMPFACMAX; |
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65 | |
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66 | // Initialization data, read from Settings. |
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67 | bool doPion, doKaon, doEta; |
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68 | double lambda, QRef; |
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69 | |
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70 | // Pointer to various information on the generation. |
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71 | Info* infoPtr; |
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72 | |
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73 | // Table of momentum shifts for different hadron species. |
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74 | int nStep[4], nStep3[4], nStored[10]; |
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75 | double QRef2, QRef3, R2Ref, R2Ref2, R2Ref3, mHadron[9], |
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76 | mPair[4], m2Pair[4], deltaQ[4], deltaQ3[4], maxQ[4], maxQ3[4]; |
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77 | double shift[4][200], shift3[4][200]; |
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78 | |
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79 | // Vector of hadrons to study. |
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80 | vector<BoseEinsteinHadron> hadronBE; |
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81 | |
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82 | // Calculate shift and (unnormalized) compensation for pair. |
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83 | void shiftPair(int i1, int i2, int iHad); |
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84 | |
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85 | }; |
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86 | |
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87 | //========================================================================== |
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88 | |
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89 | } // end namespace Pythia8 |
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90 | |
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91 | #endif // Pythia8_BoseEinstein_H |
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92 | |
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