pdgcode.cc

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/*
 * Copyright (c) 2013-2021
 *      SMASH Team
 *
 *    GNU General Public License (GPLv3 or later)
 */
 
#include <istream>
 
#include "smash/pdgcode.h"
 
namespace smash {
 
std::istream& operator>>(std::istream& is, PdgCode& code) {
  std::string codestring("");
  is >> codestring;
  if (!is) {
    code = PdgCode::invalid();
    return is;
  }
  try {
    // set the fields from the string:
    code.set_from_string(codestring);
  } catch (PdgCode::InvalidPdgCode&) {
    is.setstate(std::ios::failbit);
    code = PdgCode::invalid();
  }
  return is;
}
 
int PdgCode::net_quark_number(const int quark) const {
  // input sanitization: Only quark numbers 1 through 6 are allowed.
  if (quark < 1 || quark > 6) {
    throw std::invalid_argument(
        std::string("PdgCode::net_quark_number(): ") +
        std::string("Quark number must be in [1..6], received ") +
        std::to_string(quark));
  }
  if (is_nucleus()) {
    const int Np = nucleus_.Z_;
    const int Nn = nucleus_.A_ - nucleus_.Z_ - nucleus_.n_Lambda_;
    const int NL = nucleus_.n_Lambda_;
    switch (quark) {
      case 1:
        return (2 * Nn + Np + NL) * antiparticle_sign();
      case 2:
        return (Nn + 2 * Np + NL) * antiparticle_sign();
      case 3:
        return NL * antiparticle_sign();
      // Charmed nuclei may exist, but they are not foreseen by PDG standard
      default:
        return 0.0;
    }
  }
  // non-hadrons and those that have none of this quark type: 0.
  if (!is_hadron() || (digits_.n_q1_ != quark && digits_.n_q2_ != quark &&
                       digits_.n_q3_ != quark)) {
    return 0;
  }
  // baryons: count quarks.
  if (baryon_number() != 0) {
    // for anti-baryons, the sign changes:
    return antiparticle_sign() *
           ((digits_.n_q1_ == quark) + (digits_.n_q2_ == quark) +
            (digits_.n_q3_ == quark));
  }
 
  // mesons.
 
  // quarkonium state? Not open net_quark_number.
  if (digits_.n_q3_ == quark && digits_.n_q2_ == quark) {
    return 0;
  }
  /* this has covered all the easy stuff
   * get the "other" quark. (We know this must exist, since they are
   * not both the right one and one of them is the right one). */
  int otherquark = (digits_.n_q2_ == quark) ? digits_.n_q3_ : digits_.n_q2_;
  /* "our" quark is the heavier one: 1 for u,c,t; -1 for d,s,b (and of
   * course the antiparticle sign) */
  if (quark > otherquark) {
    return ((quark % 2 == 0) ? 1 : -1) * antiparticle_sign();
  }
  /* ours is the lighter: If the heavier particle is u,c,t, the lighter
   * one (ours) is an antiquark. */
  return ((otherquark % 2 == 0) ? -1 : 1) * antiparticle_sign();
}
 
std::ostream& operator<<(std::ostream& s, const PdgCode& code) {
  return s << code.string();
}
 
bool PdgCode::contains_enough_valence_quarks(
    int valence_quarks_required) const {
  if (is_meson()) {
    return valence_quarks_required == 1 || valence_quarks_required == -1;
  }
  if (is_baryon()) {
    if (baryon_number() == 1) {
      return valence_quarks_required == 1 || valence_quarks_required == 2;
    }
    if (baryon_number() == -1) {
      return valence_quarks_required == -1 || valence_quarks_required == -2;
    }
  }
  throw std::runtime_error("String fragment is neither baryon nor meson");
}
}  // namespace smash