Wigner.h

Go to the documentation of this file.

#ifndef AMPGEN_WIGNER_H
#define AMPGEN_WIGNER_H
#include "AmpGen/Expression.h"
#include "AmpGen/Tensor.h"
#include "AmpGen/Particle.h"
#include "AmpGen/Transform.h"
 
namespace AmpGen {
  class Particle;
  using TransformCache = std::map<std::string, TransformSequence>;
 
  namespace Helicity {
    struct Flags {
      bool movingHead = {true};
      bool alignFrames = {true};
    };
  }
  Expression wigner_d(const Expression &cb, const double &j, const double &m, const double &n);
  Expression wigner_D(const std::pair<Expression, Expression> &P, const double &J, const double &lA, const double &lB, DebugSymbols *db);
  double CG(const double &j1, const double &m1, const double &j2, const double &m2, const double &J, const double &M);

  TransformSequence wickTransform(const Tensor &P, const Particle &p, const int &ve = 1, DebugSymbols *db = nullptr);
 
  Expression helicityAmplitude(const Particle &particle, const TransformSequence &parentFrame, const double &Mz, DebugSymbols *db,
                               const Helicity::Flags &flags = Helicity::Flags(), const int sgn = 1, std::shared_ptr<TransformCache> cacheptr = nullptr);
  Tensor basisSpinor(const int &polState, const int &id);
  Tensor basisVector(const int &polState);
 
  struct LS {
    double factor = {1};
    double cg1 = {0};
    double cg2 = {0};
    double p = {0};
    double m1 = {0};
    double m2 = {0};
  };
 
  std::vector<LS> calculate_recoupling_constants(const double &J, const double &M, const double &L, const double &S, const double &j1, const double &j2);
}
 
#endif