ResonanceWidths.h

// ResonanceWidths.h is a part of the PYTHIA event generator.
// Copyright (C) 2012 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.

// Header file for resonance properties: dynamical widths etc. 
// ResonanceWidths: base class for all resonances.
// ResonanceGmZ, ...: derived classes for individual resonances.

#ifndef Pythia8_ResonanceWidths_H
#define Pythia8_ResonanceWidths_H

#include "Basics.h"
#include "Info.h"
#include "ParticleData.h"
#include "PythiaStdlib.h"
#include "Settings.h"
#include "StandardModel.h"

namespace Pythia8 {

//==========================================================================

// Forward references to ParticleData and StandardModel classes.
class DecayChannel;
class ParticleData;
class ParticleDataEntry;
class Couplings;

//==========================================================================

// The ResonanceWidths is the base class. Also used for generic resonaces.

class ResonanceWidths {

public: 

  // Destructor.
  virtual ~ResonanceWidths() {}

  // Set up standard properties.
  void initBasic(int idResIn, bool isGenericIn = false) {
    idRes = idResIn; isGeneric = isGenericIn;}
 
  // Calculate and store partial and total widths at the nominal mass. 
  virtual bool init(Info* infoPtrIn, Settings* settingsPtrIn,
    ParticleData* particleDataPtrIn, Couplings* couplingsPtrIn);

  // Return identity of particle species.
  int id() const {return idRes;}
 
  // Calculate the total/open width for given mass, charge and instate.
  double width(int idSgn, double mHatIn, int idInFlavIn = 0,  
    bool openOnly = false, bool setBR = false, int idOutFlav1 = 0, 
    int idOutFlav2 = 0); 

  // Special case to calculate open final-state width.
  double widthOpen(int idSgn, double mHatIn, int idIn = 0) {
    return width( idSgn, mHatIn, idIn, true, false);}  

  // Special case to store open final-state widths for channel selection.
  double widthStore(int idSgn, double mHatIn, int idIn = 0) {
    return width( idSgn, mHatIn, idIn, true, true);}  

  // Return fraction of width open for particle and antiparticle.
  double openFrac(int idSgn) {return (idSgn > 0) ? openPos : openNeg;}

  // Return forced rescaling factor of resonance width.
  double widthRescaleFactor() {return forceFactor;} 

  // Special case to calculate one final-state width.
  // Currently only used for Higgs -> qqbar, g g or gamma gamma. 
  double widthChan(double mHatIn, int idOutFlav1, int idOutFlav2) {
    return width( 1, mHatIn, 0, false, false, idOutFlav1, idOutFlav2);}  

protected:

  // Constructor.
  ResonanceWidths() {}

  // Constants: could only be changed in the code itself.
  static const int    NPOINT;
  static const double MASSMARGIN;

  // Particle properties always present.
  int    idRes, hasAntiRes;
  bool   doForceWidth, isGeneric;
  double minWidth, minThreshold, mRes, GammaRes, m2Res, GamMRat, 
         openPos, openNeg, forceFactor;

  // Properties for currently studied decay channel(s).
  int    iChannel, onMode, meMode, mult, id1, id2, id3, id1Abs, 
         id2Abs, id3Abs, idInFlav;
  double widNow, mHat, mf1, mf2, mf3, mr1, mr2, mr3, ps, kinFac,
         alpEM, alpS, colQ, preFac; 

  // Pointer to properties of the particle species.
  ParticleDataEntry* particlePtr;

  // Pointer to various information on the generation.
  Info*         infoPtr;

  // Pointer to the settings database.
  Settings*     settingsPtr;

  // Pointer to the particle data table.
  ParticleData* particleDataPtr;

  // Pointers to Standard Model and SUSY couplings.
  Couplings*    couplingsPtr;
 
  // Initialize constants.
  virtual void initConstants() {} 
 
  // Calculate various common prefactors for the current mass.
  // Optional argument calledFromInit only used for Z0.
  virtual void calcPreFac(bool = false) {}

  // Calculate width for currently considered channel.
  // Optional argument calledFromInit only used for Z0.
  virtual void calcWidth(bool = false) {}

  // Simple routines for matrix-element integration over Breit-Wigners.
  double numInt1BW(double mHatIn, double m1, double Gamma1, double mMin1, 
    double m2, int psMode = 1);
  double numInt2BW(double mHatIn, double m1, double Gamma1, double mMin1, 
    double m2, double Gamma2, double mMin2, int psMode = 1);

};
  
//==========================================================================

// The ResonanceGeneric class handles a generic resonance.
// Only needs a constructor; for the rest uses defaults in base class. 

class ResonanceGeneric : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceGeneric(int idResIn) {initBasic(idResIn, true);} 

};
  
//==========================================================================

// The ResonanceGmZ class handles the gamma*/Z0 resonance.

class ResonanceGmZ : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceGmZ(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  int    gmZmode;
  double thetaWRat, ei2, eivi, vi2ai2, gamNorm, intNorm, resNorm;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool calledFromInit = false);

};
  
//==========================================================================

// The ResonanceW class handles the W+- resonance.

class ResonanceW : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceW(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double thetaWRat, alpEM;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceTop class handles the top/antitop resonance.

class ResonanceTop : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceTop(int idResIn) {initBasic(idResIn);} 
 
private: 

  // Locally stored properties and couplings.
  double thetaWRat, m2W;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceFour class handles fourth-generation resonances.

class ResonanceFour : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceFour(int idResIn) {initBasic(idResIn);} 
 
private: 

  // Locally stored properties and couplings.
  double thetaWRat, m2W;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceH class handles the SM and BSM Higgs resonance.
// higgsType = 0 : SM H; = 1: h^0/H_1; = 2 : H^0/H_2; = 3 : A^0/A_3.

class ResonanceH : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceH(int higgsTypeIn, int idResIn) : higgsType(higgsTypeIn)
    {initBasic(idResIn);} 

private: 

  // Constants: could only be changed in the code itself.
  static const double MASSMINWZ, MASSMINT, GAMMAMARGIN;

  // Higgs type in current instance.
  int    higgsType;

  // Locally stored properties and couplings.
  bool   useCubicWidth, useRunLoopMass; 
  double sin2tW, cos2tW, mT, mZ, mW, mHchg, GammaT, GammaZ, GammaW,
         coup2d, coup2u, coup2l, coup2Z, coup2W, coup2Hchg, coup2H1H1, 
         coup2A3A3, coup2H1Z, coup2A3Z, coup2A3H1, coup2HchgW,
         mLowT, mStepT, mLowZ, mStepZ, mLowW, mStepW,
         kinFacT[101], kinFacZ[101], kinFacW[101];
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

  // Sum up loop contributions in Higgs -> g + g.
  double eta2gg();

  // Sum up loop contributions in Higgs -> gamma + gamma.
  double eta2gaga();

  // Sum up loop contributions in Higgs -> gamma + Z0.
  double eta2gaZ();

};
  
//==========================================================================

// The ResonanceHchg class handles the H+- resonance.

class ResonanceHchg : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceHchg(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  bool   useCubicWidth; 
  double thetaWRat, mW, tanBeta, tan2Beta, coup2H1W;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceZprime class handles the gamma*/Z0 /Z'^0 resonance.

class ResonanceZprime : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceZprime(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  int    gmZmode;
  double sin2tW, cos2tW, thetaWRat, mZ, GammaZ, m2Z, GamMRatZ, afZp[20], 
         vfZp[20], coupZpWW, ei2, eivi, vai2, eivpi, vaivapi, vapi2,
         gamNorm, gamZNorm, ZNorm, gamZpNorm, ZZpNorm, ZpNorm;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool calledFromInit = false);

};
  
//==========================================================================

// The ResonanceWprime class handles the W'+- resonance.

class ResonanceWprime : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceWprime(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double thetaWRat, cos2tW, alpEM, aqWp, vqWp, alWp, vlWp, coupWpWZ;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceRhorizontal class handles the R^0 resonance.

class ResonanceRhorizontal : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceRhorizontal(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double thetaWRat;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
   
//==========================================================================

// The ResonanceExcited class handles excited-fermion resonances.

class ResonanceExcited : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceExcited(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double Lambda, coupF, coupFprime, coupFcol, sin2tW, cos2tW;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceGraviton class handles the excited Graviton resonance.

class ResonanceGraviton : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceGraviton(int idResIn) {initBasic(idResIn);} 
 
private: 

  // Locally stored properties and couplings.
  bool   eDsmbulk, eDvlvl;
  double kappaMG;
 
  // Couplings between graviton and SM (map from particle id to coupling).
  double eDcoupling[27];

  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};

//==========================================================================

// The ResonanceKKgluon class handles the g^*/KK-gluon^* resonance.

class ResonanceKKgluon : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceKKgluon(int idResIn) {initBasic(idResIn);} 
 
private: 

  // Locally stored properties.
  double normSM, normInt, normKK;

  // Couplings between kk gluon and SM (indexed by particle id).
  // Helicity dependent couplings. Use vector/axial-vector
  // couplings internally, gv/ga = 0.5 * (gL +/- gR).
  double eDgv[10], eDga[10];

  // Interference parameter.
  int interfMode;

  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool calledFromInit = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool calledFromInit = false);

};

//==========================================================================

// The ResonanceLeptoquark class handles the LQ/LQbar resonance.

class ResonanceLeptoquark : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceLeptoquark(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double kCoup;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};

//==========================================================================

// The ResonanceNuRight class handles righthanded Majorana neutrinos.

class ResonanceNuRight : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceNuRight(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double thetaWRat, mWR;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceZRight class handles the Z_R^0 resonance.

class ResonanceZRight : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceZRight(int idResIn) {initBasic(idResIn);} 

private: 

  // Locally stored properties and couplings.
  double sin2tW, thetaWRat;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceWRight class handles the W_R+- resonance.

class ResonanceWRight : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceWRight(int idResIn) {initBasic(idResIn);} 
  
private: 

  // Locally stored properties and couplings.
  double thetaWRat;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

// The ResonanceHchgchgLeft class handles the H++/H-- (left) resonance.

class ResonanceHchgchgLeft : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceHchgchgLeft(int idResIn) {initBasic(idResIn);} 
 
private: 

  // Locally stored properties and couplings.
  double yukawa[4][4], gL, vL, mW;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
   
//==========================================================================

// The ResonanceHchgchgRight class handles the H++/H-- (right) resonance.

class ResonanceHchgchgRight : public ResonanceWidths {

public:

  // Constructor. 
  ResonanceHchgchgRight(int idResIn) {initBasic(idResIn);} 
 
private: 

  // Locally stored properties and couplings.
  int    idWR;
  double yukawa[4][4], gR;
 
  // Initialize constants.
  virtual void initConstants(); 
 
  // Calculate various common prefactors for the current mass.
  virtual void calcPreFac(bool = false);

  // Caclulate width for currently considered channel.
  virtual void calcWidth(bool = false);

};
  
//==========================================================================

} // end namespace Pythia8

#endif // Pythia8_ResonanceWidths_H