Event.cpp

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/*
 *  CepGen: a central exclusive processes event generator
 *  Copyright (C) 2013-2023  Laurent Forthomme
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <algorithm>
#include <cmath>
 
#include "CepGen/Core/Exception.h"
#include "CepGen/Event/Event.h"
#include "CepGen/Physics/HeavyIon.h"
#include "CepGen/Physics/PDG.h"
#include "CepGen/Utils/String.h"
 
namespace cepgen {
  Event::Event(bool compressed) : compressed_(compressed) {}
 
  Event::Event(const Event& oth) { *this = oth; }
 
  Event& Event::operator=(const Event& oth) {
    clear();
    particles_ = oth.particles_;
    evtcontent_ = oth.evtcontent_;
    compressed_ = oth.compressed_;
    metadata = oth.metadata;
    return *this;
  }
 
  Event Event::minimal(size_t num_out_particles) {
    auto evt = Event();
    // add the two incoming beam particles
    auto ib1 = evt.addParticle(Particle::Role::IncomingBeam1);
    ib1.get().setStatus(Particle::Status::PrimordialIncoming);
    auto ib2 = evt.addParticle(Particle::Role::IncomingBeam2);
    ib2.get().setStatus(Particle::Status::PrimordialIncoming);
 
    // add the two incoming partons
    auto part1 = evt.addParticle(Particle::Role::Parton1);
    part1.get().setStatus(Particle::Status::Incoming);
    part1.get().addMother(ib1);
    auto part2 = evt.addParticle(Particle::Role::Parton2);
    part2.get().setStatus(Particle::Status::Incoming);
    part2.get().addMother(ib2);
    // add the two-parton system
    auto twopart = evt.addParticle(Particle::Role::Intermediate);
    twopart.get().setStatus(Particle::Status::Propagator);
    twopart.get().addMother(part1);
    twopart.get().addMother(part2);
 
    // add the two outgoing beam particles
    auto ob1 = evt.addParticle(Particle::Role::OutgoingBeam1);
    ob1.get().setStatus(Particle::Status::FinalState);
    ob1.get().addMother(ib1);
    auto ob2 = evt.addParticle(Particle::Role::OutgoingBeam2);
    ob2.get().setStatus(Particle::Status::FinalState);
    ob2.get().addMother(ib2);
 
    // finally add the central system
    for (size_t i = 0; i < num_out_particles; ++i) {
      auto cs = evt.addParticle(Particle::Role::CentralSystem);
      cs.get().setStatus(Particle::Status::FinalState);
      cs.get().addMother(twopart);
    }
    return evt;
  }
 
  void Event::clear() {
    particles_.clear();
    metadata.clear();
  }
 
  void Event::freeze() {
    if (particles_.count(Particle::CentralSystem) > 0)
      evtcontent_.cs = particles_[Particle::CentralSystem].size();
    if (particles_.count(Particle::OutgoingBeam1) > 0)
      evtcontent_.op1 = particles_[Particle::OutgoingBeam1].size();
    if (particles_.count(Particle::OutgoingBeam2) > 0)
      evtcontent_.op2 = particles_[Particle::OutgoingBeam2].size();
  }
 
  void Event::restore() {
    if (particles_.count(Particle::CentralSystem) > 0)
      particles_[Particle::CentralSystem].resize(evtcontent_.cs);
    if (particles_.count(Particle::OutgoingBeam1) > 0)
      particles_[Particle::OutgoingBeam1].resize(evtcontent_.op1);
    if (particles_.count(Particle::OutgoingBeam2) > 0)
      particles_[Particle::OutgoingBeam2].resize(evtcontent_.op2);
  }
 
  bool Event::compressed() const { return compressed_; }
 
  Event Event::compress() const {
    if (compressed_)
      return *this;
    Event out(/*compressed=*/true);
    int i = 0;
    //--- add all necessary particles
    for (const auto& role : {Particle::IncomingBeam1,
                             Particle::IncomingBeam2,
                             Particle::OutgoingBeam1,
                             Particle::OutgoingBeam2,
                             Particle::Parton1,
                             Particle::Parton2,
                             Particle::CentralSystem}) {
      if (particles_.count(role) == 0)
        continue;
      for (const auto& old_part : operator()(role)) {
        auto& new_part = out.addParticle(role).get();
        new_part = old_part;  // copy all attributes
        new_part.setId(i++);
        new_part.clearMothers();
        new_part.clearDaughters();
      }
    }
    //--- fix parentage for outgoing beam particles
    if (out[Particle::OutgoingBeam1].size() > 1 || out[Particle::OutgoingBeam2].size() > 1)
      CG_WARNING("Event:compress") << "Event compression not designed for already fragmented beam remnants!\n\t"
                                   << "Particles parentage is not guaranteed to be conserved.";
    if (particles_.count(Particle::OutgoingBeam1) > 0)
      for (auto& part : out[Particle::OutgoingBeam1])
        part.get().addMother(out[Particle::IncomingBeam1][0].get());
    if (particles_.count(Particle::OutgoingBeam2) > 0)
      for (auto& part : out[Particle::OutgoingBeam2])
        part.get().addMother(out[Particle::IncomingBeam2][0].get());
    //--- fix parentage for incoming partons
    for (auto& part : out[Particle::Parton1])
      if (particles_.count(Particle::IncomingBeam1) > 0)
        part.get().addMother(out[Particle::IncomingBeam1][0].get());
    if (particles_.count(Particle::IncomingBeam2) > 0)
      for (auto& part : out[Particle::Parton2])
        part.get().addMother(out[Particle::IncomingBeam2][0].get());
    //--- fix parentage for central system
    if (particles_.count(Particle::Parton1) > 0 && particles_.count(Particle::Parton2) > 0)
      for (auto& part : out[Particle::CentralSystem]) {
        part.get().addMother(out[Particle::Parton1][0]);
        part.get().addMother(out[Particle::Parton2][0]);
      }
    return out;
  }
 
  ParticlesRefs Event::operator[](Particle::Role role) {
    ParticlesRefs out;
    //--- retrieve all particles with a given role
    for (auto& part : particles_[role])
      out.emplace_back(std::ref(part));
    return out;
  }
 
  const Particles& Event::operator()(Particle::Role role) const {
    if (particles_.count(role) == 0)
      throw CG_FATAL("Event") << "Failed to retrieve a particle with " << role << " role.";
    //--- retrieve all particles with a given role
    return particles_.at(role);
  }
 
  ParticlesIds Event::ids(Particle::Role role) const {
    ParticlesIds out;
    //--- retrieve all particles ids with a given role
    if (particles_.count(role) == 0)
      return out;
 
    for (const auto& part : particles_.at(role))
      out.insert(part.id());
 
    return out;
  }
 
  Particle& Event::oneWithRole(Particle::Role role) {
    //--- retrieve the first particle of a given role
    auto parts_by_role = operator[](role);
    if (parts_by_role.empty())
      throw CG_FATAL("Event") << "No particle retrieved with " << role << " role.";
    if (parts_by_role.size() > 1)
      throw CG_FATAL("Event") << "More than one particle with " << role << " role: " << parts_by_role.size()
                              << " particles.";
    return parts_by_role.front().get();
  }
 
  const Particle& Event::oneWithRole(Particle::Role role) const {
    //--- retrieve the first particle of a given role
    const Particles& parts_by_role = operator()(role);
    if (parts_by_role.empty())
      throw CG_FATAL("Event") << "No particle retrieved with " << role << " role.";
    if (parts_by_role.size() > 1)
      throw CG_FATAL("Event") << "More than one particle with " << role << " role: " << parts_by_role.size()
                              << " particles";
    return *parts_by_role.begin();
  }
 
  Particle& Event::operator[](int id) {
    for (auto& role_part : particles_)
      for (auto& part : role_part.second)
        if (part.id() == id)
          return part;
 
    throw CG_FATAL("Event") << "Failed to retrieve the particle with id=" << id << ".";
  }
 
  const Particle& Event::operator()(int id) const {
    for (const auto& role_part : particles_) {
      auto it = std::find_if(
          role_part.second.begin(), role_part.second.end(), [&id](const auto& part) { return part.id() == id; });
      if (it != role_part.second.end())
        return *it;
    }
 
    throw CG_FATAL("Event") << "Failed to retrieve the particle with id=" << id << ".";
  }
 
  ParticlesRefs Event::operator[](const ParticlesIds& ids) {
    ParticlesRefs out;
    std::transform(ids.begin(), ids.end(), std::back_inserter(out), [this](const auto& id) {
      return std::ref(this->operator[](id));
    });
    return out;
  }
 
  Particles Event::operator()(const ParticlesIds& ids) const {
    Particles out;
    std::transform(
        ids.begin(), ids.end(), std::back_inserter(out), [this](const auto& id) { return this->operator()(id); });
    return out;
  }
 
  Particles Event::mothers(const Particle& part) const { return operator()(part.mothers()); }
 
  ParticlesRefs Event::mothers(const Particle& part) { return operator[](part.mothers()); }
 
  Particles Event::daughters(const Particle& part) const { return operator()(part.daughters()); }
 
  ParticlesRefs Event::daughters(const Particle& part) { return operator[](part.daughters()); }
 
  Particles Event::stableDaughters(const Particle& part, bool recursive) const {
    Particles parts;
    for (const auto& daugh : operator()(part.daughters())) {
      if (daugh.status() == Particle::Status::FinalState)
        parts.emplace_back(daugh);
      else if (recursive) {
        const auto daugh_daugh = stableDaughters(daugh, recursive);
        parts.insert(
            parts.end(), std::make_move_iterator(daugh_daugh.begin()), std::make_move_iterator(daugh_daugh.end()));
      }
    }
    return parts;
  }
 
  ParticlesRefs Event::stableDaughters(const Particle& part, bool recursive) {
    ParticlesRefs parts;
    for (const auto& daugh : operator[](part.daughters())) {
      if (daugh.get().status() == Particle::Status::FinalState)
        parts.emplace_back(daugh);
      else if (recursive) {
        const auto daugh_daugh = stableDaughters(daugh, recursive);
        parts.insert(
            parts.end(), std::make_move_iterator(daugh_daugh.begin()), std::make_move_iterator(daugh_daugh.end()));
      }
    }
    return parts;
  }
 
  ParticleRoles Event::roles() const {
    ParticleRoles out;
    std::transform(
        particles_.begin(), particles_.end(), std::back_inserter(out), [](const auto& pr) { return pr.first; });
    return out;
  }
 
  ParticleRef Event::addParticle(Particle& part, bool replace) {
    CG_DEBUG_LOOP("Event") << "Particle with PDGid = " << part.integerPdgId() << " has role " << part.role();
    if (part.role() <= 0)
      throw CG_FATAL("Event") << "Trying to add a particle with role=" << (int)part.role() << ".";
 
    auto& part_with_same_role = particles_[part.role()];  // list of particles with the same role
    if (part.id() < 0)
      part.setId(part_with_same_role.empty() || !replace
                     ? size()                         // set the id if previously invalid/non-existent
                     : part_with_same_role[0].id());  // set the previous id if replacing a particle
    if (replace)
      part_with_same_role = {part};
    else
      part_with_same_role.emplace_back(part);
    return std::ref(part_with_same_role.back());
  }
 
  ParticleRef Event::addParticle(Particle::Role role, bool replace) {
    Particle np(role, PDG::invalid);
    return addParticle(np, replace);
  }
 
  size_t Event::size() const {
    return std::accumulate(particles_.begin(), particles_.end(), 0, [](size_t size, const auto& role_part) {
      return size + role_part.second.size();
    });
  }
 
  bool Event::empty() const { return particles_.empty(); }
 
  Particles Event::particles() const {
    Particles out;
    for (const auto& role_part : particles_)
      out.insert(out.end(), role_part.second.begin(), role_part.second.end());
 
    std::sort(out.begin(), out.end());
    return out;
  }
 
  Particles Event::stableParticles() const {
    Particles out;
    for (const auto& role_part : particles_)
      std::copy_if(role_part.second.begin(), role_part.second.end(), std::back_inserter(out), [](const auto& part) {
        return (short)part.status() > 0;
      });
 
    std::sort(out.begin(), out.end());
    return out;
  }
 
  Momentum Event::missingMomentum() const {
    Momentum me;
    for (const auto& cp : operator()(Particle::Role::CentralSystem))
      if (cp.status() == Particle::Status::FinalState) {
        const auto pdg = cp.integerPdgId();
        if (pdg == 12 || pdg == 14 || pdg == 16)  // neutrinos
          me += cp.momentum();
        if (pdg == 1000022 || pdg == 1000023 || pdg == 1000025 || 1000035)  // neutralinos
          me += cp.momentum();
      }
    return me;
  }
 
  void Event::checkKinematics() const {
    // check the kinematics through parentage
    for (const auto& part : particles()) {
      ParticlesIds daughters = part.daughters();
      if (daughters.empty())
        continue;
      Momentum ptot;
      for (const auto& daughter : daughters) {
        const auto& d = operator()(daughter);
        const auto mothers = d.mothers();
        ptot += d.momentum();
        if (mothers.size() < 2)
          continue;
        for (const auto& moth : mothers)
          if (moth != part.id())
            ptot -= operator()(moth).momentum();
      }
      const double mass_diff = (ptot - part.momentum()).mass();
      if (fabs(mass_diff) > MIN_PRECISION) {
        dump();
        throw CG_FATAL("Event") << "Error in momentum balance for particle " << part.id() << ": mdiff = " << mass_diff
                                << ".";
      }
    }
  }
 
  void Event::dump() const { CG_INFO("Event") << *this; }
 
  std::ostream& operator<<(std::ostream& out, const Event& ev) {
    const auto parts = ev.particles();
    std::ostringstream os;
 
    Momentum p_total;
    for (const auto& part : parts) {
      const ParticlesIds mothers = part.mothers();
      {
        std::ostringstream oss_pdg;
        if (part.pdgId() == PDG::invalid && !mothers.empty()) {
          //--- if particles compound
          std::string delim;
          for (size_t i = 0; i < mothers.size(); ++i)
            try {
              oss_pdg << delim << (PDG::Id)ev(*std::next(mothers.begin(), i)).pdgId(), delim = "/";
            } catch (const Exception&) {
              oss_pdg << delim << ev(*std::next(mothers.begin(), i)).pdgId(), delim = "/";
            }
          os << utils::format("\n %2d\t\t   %-7s", part.id(), oss_pdg.str().c_str());
        } else {
          //--- if single particle/HI
          if (HeavyIon::isHI(part.pdgId()))
            oss_pdg << HeavyIon::fromPdgId(part.pdgId());
          else
            try {
              oss_pdg << (PDG::Id)part.pdgId();
            } catch (const Exception&) {
              oss_pdg << "?";
            }
          os << utils::format("\n %2d\t%-+10d %-7s", part.id(), part.integerPdgId(), oss_pdg.str().c_str());
        }
      }
      os << "\t";
      if (part.charge() != (int)part.charge()) {
        if (part.charge() * 2 == (int)(part.charge() * 2))
          os << utils::format("%-d/2", (int)(part.charge() * 2));
        else if (part.charge() * 3 == (int)(part.charge() * 3))
          os << utils::format("%-d/3", (int)(part.charge() * 3));
        else
          os << utils::format("%-.2f", part.charge());
      } else
        os << utils::format("%-g", part.charge());
      os << "\t";
      {
        std::ostringstream oss;
        oss << part.role();
        os << utils::format("%-8s %6d\t", oss.str().c_str(), part.status());
      }
      if (!mothers.empty()) {
        std::ostringstream oss;
        unsigned short i = 0;
        for (const auto& moth : mothers) {
          oss << (i > 0 ? "+" : "") << moth;
          ++i;
        }
        os << utils::format("%6s ", oss.str().c_str());
      } else
        os << "       ";
      const auto& mom = part.momentum();
      os << utils::format(
          "% 9.6e % 9.6e % 9.6e % 9.6e % 12.5f", mom.px(), mom.py(), mom.pz(), mom.energy(), mom.mass());
 
      // discard non-primary, decayed particles
      if (part.status() >= Particle::Status::Undefined) {
        const int sign = (part.status() == Particle::Status::Undefined) ? -1 : +1;
        p_total += sign * mom;
      }
    }
    //--- set a threshold to the computation precision
    p_total.truncate();
    //
    return out << utils::format(
               "Event content:\n"
               " Id\tPDG id\t   Name\t\tCharge\tRole\t Status\tMother\tpx            py            pz            E   "
               "  "
               " \t M         \n"
               " --\t------\t   ----\t\t------\t----\t ------\t------\t----GeV/c---  ----GeV/c---  ----GeV/c---  "
               "----GeV/c---\t --GeV/c²--"
               "%s\n"
               " ----------------------------------------------------------------------------------------------------"
               "--"
               "----------------------------\n"
               "\t\t\t\t\t\t\tBalance% 9.6e % 9.6e % 9.6e % 9.6e",
               os.str().c_str(),
               p_total.px(),
               p_total.py(),
               p_total.pz(),
               p_total.energy());
  }
 
  Event::EventMetadata::EventMetadata()
      : std::unordered_map<std::string, float>{{"time:generation", -1.f},
                                               {"time:total", -1.f},
                                               {"weight", 1.f},
                                               {"alphaEM", (float)constants::ALPHA_EM},
                                               {"alphaS", (float)constants::ALPHA_QCD}} {}
}  // namespace cepgen