Line data    Source code

       1             : // HardDiffraction.h is a part of the PYTHIA event generator.
       2             : // Copyright (C) 2015 Torbjorn Sjostrand.
       3             : // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
       4             : // Please respect the MCnet Guidelines, see GUIDELINES for details.
       5             : 
       6             : // Author: Christine Rasmussen.
       7             : 
       8             : // Header file for the HardDiffraction class.
       9             : 
      10             : #ifndef Pythia8_HardDiffraction_H
      11             : #define Pythia8_HardDiffraction_H
      12             : 
      13             : #include "Pythia8/Basics.h"
      14             : #include "Pythia8/BeamParticle.h"
      15             : #include "Pythia8/BeamRemnants.h"
      16             : #include "Pythia8/Info.h"
      17             : #include "Pythia8/MultipartonInteractions.h"
      18             : #include "Pythia8/PythiaStdlib.h"
      19             : #include "Pythia8/Settings.h"
      20             : #include "Pythia8/SpaceShower.h"
      21             : #include "Pythia8/TimeShower.h"
      22             : 
      23             : namespace Pythia8 {
      24             : 
      25             : //==========================================================================
      26             : 
      27             : // HardDiffraction class.
      28             : // This class handles hard diffraction, together with PartonLevel.
      29             : 
      30             : class HardDiffraction {
      31             : 
      32             : public:
      33             : 
      34             :   // Constructor and destructor.
      35           0 :   HardDiffraction() {};
      36           0 :   ~HardDiffraction() {}
      37             : 
      38             :   // Initialise constants
      39             :   void init(Info* infoPtrIn, Settings& settingsIn, Rndm* rndmPtrIn,
      40             :     BeamParticle* beamAPtrIn, BeamParticle* beamBPtrIn,
      41             :     BeamParticle* beamPomAPtrIn, BeamParticle* beamPomBPtrIn);
      42             : 
      43             :   // Main routine to check if event is from diffractive PDF.
      44             :   bool isDiffractive(int iBeamIn = 1, int partonIn = 0,
      45             :     double xIn = 0., double Q2In = 0., double xfIncIn = 0.);
      46             : 
      47             :   // Get diffractive values.
      48           0 :   double getXPomeronA()     {return xPomA;}
      49           0 :   double getXPomeronB()     {return xPomB;}
      50           0 :   double getTPomeronA()     {return tPomA;}
      51           0 :   double getTPomeronB()     {return tPomB;}
      52           0 :   double getThetaPomeronA() {return thetaPomA;}
      53           0 :   double getThetaPomeronB() {return thetaPomB;}
      54             : 
      55             : private:
      56             : 
      57             :   // Constants: could only be changed in the code itself.
      58             :   static const double TINYPDF;
      59             :   static const double POMERONMASS;
      60             :   static const double PROTONMASS;
      61             : 
      62             :   // Initialization and event data.
      63             :   int    pomSet, pomFlux, iBeam, idA, idB;
      64             :   double normPom, a1, a2, a3, A1, A2, A3, a0, ap, b0,
      65             :          mA, mB, s, s1, s2, s3, s4,
      66             :          xPomA, xPomB, tPomA, tPomB, thetaPomA, thetaPomB;
      67             : 
      68             :   // Pointer to various information on the generation.
      69             :   Info*           infoPtr;
      70             : 
      71             :   // Pointer to the settings database.
      72             :   Settings        settings;
      73             : 
      74             :   // Pointer to the random number generator.
      75             :   Rndm*           rndmPtr;
      76             : 
      77             :   // Pointers to incoming beams.
      78             :   BeamParticle*   beamAPtr;
      79             :   BeamParticle*   beamBPtr;
      80             :   BeamParticle*   beamPomAPtr;
      81             :   BeamParticle*   beamPomBPtr;
      82             : 
      83             :   // Pointer to temporary Pomeron PDF.
      84             :   BeamParticle*   tmpPDFPtr;
      85             : 
      86             :   // Return Pomeron flux inside proton, integrated over t.
      87             :   double xfPom(double xIn = 0.);
      88             : 
      89             :   // Pick a t value for a given x.
      90             :   double pickTNow(double xIn = 0.);
      91             : 
      92             :   // Return Pomeron flux inside proton, differential in t.
      93             :   double xfPomWithT(double xIn = 0., double tIn = 0.);
      94             : 
      95             :   // Make t range available as a pair.
      96             :   pair<double, double> tRange(double xIn = 0.);
      97             : 
      98             :   // Calculate scattering angle from  given x and t.
      99             :   double getThetaNow(double xIn = 0., double tIn = 0.);
     100             : 
     101             : };
     102             : 
     103             : //==========================================================================
     104             : 
     105             : } // end namespace Pythia8
     106             : 
     107             : #endif // Pythia8_HardDiffraction_H