mass_schemes.hpp

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#pragma once
#include <array>
#include <string>
#include <ostream>

namespace QQbar_threshold{


  enum scheme_name{
    PS,
    PSshift,
    OneS,
    OneSshift,
    Pole,
    MSshift,
    MSbarshift = MSshift,
    MSbar = MSshift,
    last_mass_scheme = MSbar
  };


  struct scheme{
    scheme_name name;
    double scale;
    double nu;
  };

  inline
  std::string to_string(scheme s){
    using std::to_string;
    static constexpr
      std::array<char const *, last_mass_scheme + 1> name_strings = {{
    "PS", "PSshift", "OneS", "OneSshift", "Pole", "MSbar"
      }};
    std::string result =
      std::string{'{'} + name_strings[s.name] + ", " + to_string(s.scale);
    if((s.name == PS || s.name == PSshift) && (s.scale != s.nu)) {
      result += ", " + to_string(s.nu);
    }
    return result + '}';
  }

  inline
  std::ostream& operator<<(std::ostream& os, scheme s){
    os << to_string(s);
    return os;
  }

  inline bool is_threshold_mass(scheme_name s){
    switch(s){
    case Pole:
    case PSshift:
    case OneSshift:
    case MSbar:
      return false;
    default: return true;
    }
  }

  inline bool is_threshold_mass(scheme const & s){
    return is_threshold_mass(s.name);
  }


  inline bool is_shifted_mass(scheme_name  s){
    switch(s){
    case PSshift:
    case OneSshift:
    case MSbar:
      return true;
    default: return false;
    }
  }


  inline scheme_name to_shifted_mass(scheme_name  s){
    switch(s){
    case PS: return PSshift;
    case OneS: return OneSshift;
    default: return s;
    }
  }


  inline bool is_shifted_mass(scheme const & s){
    return is_shifted_mass(s.name);
  }
}