kMatrix.h

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#ifndef AMPGEN_KMATRIX_H
#define AMPGEN_KMATRIX_H
 
#include "AmpGen/Expression.h"
#include "AmpGen/Tensor.h"
#include "AmpGen/Lineshapes.h"
 
namespace AmpGen {
  namespace Lineshape {
    DECLARE_LINESHAPE(kMatrix);
  }
 
  struct poleConfig {
    Expression s;
    std::vector<Expression> couplings;
    std::vector<Expression> bl_factors;
    poleConfig(const Expression &s, const std::vector<Expression> &c = {}) : s(s), couplings(c), bl_factors(c.size(), 1) {};
 
    void add(const Expression &coupling, const Expression &bl_factor = 1) {
      couplings.push_back(coupling);
      bl_factors.push_back(bl_factor);
    }
    const Expression coupling(const unsigned &i) const { return couplings[i] * bl_factors[i]; }
    const Expression g(const unsigned &i) const { return couplings[i]; }
  };
 
  Tensor constructKMatrix(const Expression &s, const unsigned &nChannels, const std::vector<poleConfig> &poleConfigs);
 
  Expression phsp_twoBody(const Expression &s, const double &m0, const double &m1);
  Expression phsp_fourPi(const Expression &s);
  Expression phsp_FOCUS(const Expression &s, const double &m0, const double &m1);
  Expression gFromGamma(const Expression &m, const Expression &gamma, const Expression &rho);
 
  std::vector<Variable> paramVector(const std::string &name, const unsigned int &nParam);
 
  Tensor getPropagator(const Tensor &kMatrix, const std::vector<Expression> &phaseSpace, DebugSymbols *db = nullptr);
} // namespace AmpGen
 
#endif /* end of include guard: AMPGEN_KMATRIX_H */