EvtLambdaP_BarGamma.hh

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 2003      Caltech
//
// Module: EvtGen/EvtRadiativeBaryonicPenguins.hh
//
// Description:Implementation of the decay B- -> lambda p_bar gamma according to
// Cheng, Yang; hep-ph/0201015
//
// Modification history:
//
//    JFS     December 16th, 2003         Module created
//
//------------------------------------------------------------------------
 
#ifndef EVTLAMBDAPBARGAMMA_HH
#define EVTLAMBDAPBARGAMMA_HH
 
#include "../EvtGenBase/EvtComplex.hh"
#include "../EvtGenBase/EvtConst.hh"
#include "../EvtGenBase/EvtDecayAmp.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
 
class EvtLambdaP_BarGamma : public EvtDecayAmp {
 
public:
  EvtLambdaP_BarGamma();
  ~EvtLambdaP_BarGamma() { ; }
 
  void          getName( std::string& name );
  EvtDecayBase* clone();
  void          decay( EvtParticle* p );
  void          init();
  void          initProbMax();
 
private:
  // some constants to make the code easier to read and maintain
  // these three should be constants... (implementation of getMass() prohibits this)
  double _mLambdab; //  = 5.624;                          // Lambda_b mass
  double _mLambda0; //  = 1.115684;                       // Lambda0 mass
  double _c7Eff;    //  = -0.31;                          // Wilson coefficient
  double _mb;       //  =  4.4;                           // running b mass
  double _mV;       //  =  5.42;                          // pole mass vector current
  double _mA;       //  =  5.86;                          // pole mass axial current
  double _GF;       //  =  1.166E-5;                      // Fermi constant
  double _gLambdab; // =  16;                            // coupling constant Lambda_b -> B- p
  double _e0;       //  =  1;                             // electromagnetic coupling (+1)
  double _g1; //  =  0.64;                          // heavy-light form factors at q_mSqare
  double _g2; //  = -0.10;
  double _f1; //  =  0.64;
  double _f2; //  = -0.31;
  double _VtbVtsStar; // = 0.038;                          // |V_tb V_ts^*|
 
  // user never needs to call this -> private
  // baryonic form factors f(p), g(p), at p=0
  const double f0( const double f_qm, int n = 1 ); // calculate f(0) with f(q_max)
  const double g0( const double f_qm, int n = 1 ); // calculate g(0) with g(q_max)
 
  // shorthand for constants a and b in the formula
  const double constA();
  const double constB();
 
  // initialize phasespace and calculate the amplitude for one (i=0,1) state of the photon
  EvtComplex calcAmpliude( const EvtParticle* p, const unsigned int polState );
};
 
#endif