#include <listmodus.h>

ListModus: Provides a modus for running SMASH on an external particle list, for example as an afterburner calculation.

To use this modus, choose Modus: List

General:

Modus: List

in the configuration file.

Options for ListModus go in the "Modi"→"List" section of the configuration:

Modi:
     List:
             # options here

For configuring see List.

Since SMASH is searching for collisions in computational frame time 't', all particles need to be at the same time. If this is not the case in the list provided, the particles will be propagated backwards on straight lines ("anti-freestreaming"). To avoid unphysical interactions of these particles, the back-propagated particles receive a formation_time and zero cross_section_scaling_factor. The cross-sections are set to zero during the time, where the particle will just propagate on a straight line again to appear at the formation_time into the system.

Definition at line 56 of file listmodus.h.

Inheritance diagram for smash::ListModus:

Classes
struct	LoadFailure
	Used when external particle list cannot be found. More...

Public Member Functions
	ListModus (Configuration modus_config, const ExperimentParameters &parameters)
	Constructor. More...

	ListModus ()=default
	Construct an empty list. More...

double	initial_conditions (Particles *particles, const ExperimentParameters &parameters)
	Generates initial state of the particles in the system according to a list. More...

void	backpropagate_to_same_time (Particles &particles)
	Judge whether formation times are the same for all the particles; Don't do anti-freestreaming if all particles start already at the same time. More...

void	try_create_particle (Particles &particles, PdgCode pdgcode, double t, double x, double y, double z, double mass, double E, double px, double py, double pz)
	Tries to add a new particle to particles and performs consistency checks: (i) The PDG code is legal and exists in SMASH. More...

bool	is_list () const

Public Member Functions inherited from smash::ModusDefault
int	impose_boundary_conditions (Particles *, const OutputsList &={})
	Enforces sensible positions for the particles. More...

bool	is_collider () const

bool	is_box () const

bool	is_list () const

bool	is_sphere () const

double	sqrt_s_NN () const

double	impact_parameter () const

void	sample_impact () const
	sample impact parameter for collider modus More...

double	velocity_projectile () const

double	velocity_target () const

FermiMotion	fermi_motion () const

double	max_timestep (double) const

double	equilibration_time () const

double	length () const

double	radius () const

bool	calculation_frame_is_fixed_target () const

double	nuclei_passing_time () const
	Get the passing time of the two nuclei in a collision. More...

Grid< GridOptions::Normal >	create_grid (const Particles &particles, double min_cell_length, double timestep_duration, CollisionCriterion crit, const bool include_unformed_particles, CellSizeStrategy strategy=CellSizeStrategy::Optimal) const
	Creates the Grid with normal boundary conditions. More...

std::unique_ptr< GrandCanThermalizer >	create_grandcan_thermalizer (Configuration &conf) const
	Creates GrandCanThermalizer. More...

Protected Attributes
double	start_time_ = 0.
	Starting time for the List; changed to the earliest formation time. More...

Private Member Functions
bool	file_has_events_ (std::filesystem::path filepath, std::streampos last_position)
	Check if the file given by filepath has events left after streampos last_position. More...

std::filesystem::path	file_path_ (std::optional< int > file_id)
	Return the absolute path of the data file. More...

std::string	next_event_ ()
	Read the next event. More...

Private Attributes
std::string	particle_list_file_directory_
	File directory of the particle list. More...

std::string	particle_list_filename_or_prefix_
	Prefix of the file(s) containing the particle list. More...

std::optional< int >	file_id_
	The id of the current file. More...

int	event_id_
	The unique id of the current event. More...

std::streampos	last_read_position_ = 0
	Last read position in current file. More...

bool	warn_about_mass_discrepancy_ = true
	Auxiliary flag to warn about mass-discrepancies only once per instance. More...

bool	warn_about_off_shell_particles_ = true
	Auxiliary flag to warn about off-shell particles only once per instance. More...

Friends
std::ostream &	operator<< (std::ostream &, const ListModus &)
	Writes the initial state for the List to the output stream. More...

Constructor & Destructor Documentation

◆ ListModus() [1/2]

smash::ListModus::ListModus	(	Configuration	modus_config,
		const ExperimentParameters &	parameters
	)

explicit

Constructor.

Gathers all configuration variables for the List.

Parameters

[in]	modus_config	The configuration object that sets all initial conditions of the experiment.
[in]	parameters	Necessary because of templated usage in Experiment.

Definition at line 38 of file listmodus.cc.

     : file_id_{std::nullopt}, event_id_{0} {
   /*
    * Extract the only expected section of the configuration to make this
    * constructor work also for children classes. These do the same but have a
    * different section name (like for instance 'ListBox' instead of 'List')
    */
   const auto config_sections = modus_config.list_upmost_nodes();
   assert(config_sections.size() == 1);
   auto plain_config =
       modus_config.extract_sub_configuration({config_sections[0].c_str()});
   // Impose strict requirement on possible keys present in configuration file
   bool file_prefix_used = plain_config.has_value({"File_Prefix"});
   bool filename_used = plain_config.has_value({"Filename"});
   if (file_prefix_used == filename_used) {
     throw std::invalid_argument(
         "Either 'Filename' or 'File_Prefix' key must be used in 'List' section "
         "in configuration file. Please, adjust your configuration file.");
   }
   std::string key_to_take = "Filename";
   if (file_prefix_used) {
     key_to_take = "File_Prefix";
     file_id_ = plain_config.take({"Shift_Id"}, 0);
   }
   particle_list_filename_or_prefix_ =
       plain_config.take({key_to_take.c_str()})
           .convert_for(particle_list_filename_or_prefix_);
   particle_list_file_directory_ =
       plain_config.take({"File_Directory"})
           .convert_for(particle_list_file_directory_);
   if (param.n_ensembles > 1) {
     throw std::runtime_error("ListModus only makes sense with one ensemble");
   }
 }

◆ ListModus() [2/2]

smash::ListModus::ListModus ( )

default

Construct an empty list.

This is needed for children construction but it is offered as public instead of protected as it is also useful for JetScape.

Member Function Documentation

◆ initial_conditions()

double smash::ListModus::initial_conditions	(	Particles *	particles,
		const ExperimentParameters &	parameters
	)

Generates initial state of the particles in the system according to a list.

Parameters

[out]	particles	An empty list that gets filled up by this function
[in]	parameters	Unused, but necessary because of templated use of this function

Returns: The starting time of the simulation

Exceptions

runtime_error	if an input list file could not be found
LoadFailure	if an input list file is not correctly formatted
invalid_argument	if the listed charge of a particle does not correspond to its pdg charge

Definition at line 135 of file listmodus.cc.

                                                                    {
   std::string particle_list = next_event_();
   for (const Line &line : line_parser(particle_list)) {
     std::istringstream lineinput(line.text);
     double t, x, y, z, mass, E, px, py, pz;
     int id, charge;
     std::string pdg_string;
     lineinput >> t >> x >> y >> z >> mass >> E >> px >> py >> pz >>
         pdg_string >> id >> charge;
     if (lineinput.fail()) {
       throw LoadFailure(
           build_error_string("While loading external particle lists data:\n"
                              "Failed to convert the input string to the "
                              "expected data types.",
                              line));
     }
     PdgCode pdgcode(pdg_string);
     logg[LList].debug("Particle ", pdgcode, " (x,y,z)= (", x, ", ", y, ", ", z,
                       ")");
  
     // Charge consistency check
     if (pdgcode.charge() != charge) {
       logg[LList].error() << "Charge of pdg = " << pdgcode << " != " << charge;
       throw std::invalid_argument("Inconsistent input (charge).");
     }
     try_create_particle(*particles, pdgcode, t, x, y, z, mass, E, px, py, pz);
   }
   if (particles->size() > 0) {
     backpropagate_to_same_time(*particles);
   } else {
     start_time_ = 0.0;
   }
   event_id_++;
  
   return start_time_;
 }

◆ backpropagate_to_same_time()

void smash::ListModus::backpropagate_to_same_time ( Particles & particles )

Judge whether formation times are the same for all the particles; Don't do anti-freestreaming if all particles start already at the same time.

If particles are at different times, calculate earliest formation time as start_time_ and free-stream all particles back to this time.

Parameters

particles particles to be checked and possibly back-streamed

Definition at line 81 of file listmodus.cc.

                                                                {
   /* (1) If particles are already at the same time - don't touch them
          AND start at the start_time_ from the config. */
   double earliest_formation_time = DBL_MAX;
   double formation_time_difference = 0.0;
   double reference_formation_time = 0.0;  // avoid compiler warning
   bool first_particle = true;
   for (const auto &particle : particles) {
     const double t = particle.position().x0();
     if (t < earliest_formation_time) {
       earliest_formation_time = t;
     }
     if (first_particle) {
       reference_formation_time = t;
       first_particle = false;
     } else {
       formation_time_difference += std::abs(t - reference_formation_time);
     }
   }
   /* (2) If particles are NOT at the same time -> anti-stream them to
          the earliest time (Note: not to the start_time_ set by config) */
   bool anti_streaming_needed = (formation_time_difference > really_small);
   start_time_ = earliest_formation_time;
   if (anti_streaming_needed) {
     for (auto &particle : particles) {
       /* for hydro output where formation time is different */
       const double t = particle.position().x0();
       const double delta_t = t - start_time_;
       const ThreeVector r =
           particle.position().threevec() - delta_t * particle.velocity();
       particle.set_4position(FourVector(start_time_, r));
       particle.set_formation_time(t);
       particle.set_cross_section_scaling_factor(0.0);
     }
   }
 }

◆ try_create_particle()

void smash::ListModus::try_create_particle	(	Particles &	particles,
		PdgCode	pdgcode,
		double	t,
		double	x,
		double	y,
		double	z,
		double	mass,
		double	E,
		double	px,
		double	py,
		double	pz
	)

Tries to add a new particle to particles and performs consistency checks: (i) The PDG code is legal and exists in SMASH.

If not, a warning is printed and the particle is ignored. (ii) The mass matches the pole mass of pdgcode in SMASH. If it does not, then a warning is printed, the pole mass of the particle is set equal to the corresponding mass from SMASH particle table and it's energy is recomputed as \( E^2 = p^2 + m^2 \). (iii) Any stable particle is on-shell, i.e. \( E^2 - p^2 = m^2 \). If it is not, then a warning is printed and the energy is set to \( E^2 = p^2 + m^2 \). (iv) If there are nan values in the position or momentum of the particle an exception is thrown.

This very tolerant behaviour is justified by the practical usage of SMASH as afterburner. Usually particles unknown to SMASH are rare resonances, which do not play a large role. Mass mismatch is typically less than 1% and comes from rounding and from SMASH enforcing isospin symmetry (for example the mass of neutral pion is artificially forced to be the same as charged pion). On-shellness violation typically comes from the insufficient number of significant digits in the input file + rounding.

Parameters

[in]	pdgcode	pdg code of added particle
[in]	t	time of added particle
[in]	x	x-coordinate of added particle
[in]	y	y-coordinate of added particle
[in]	z	z-coordinate of added particle
[in]	mass	mass of added particle
[in]	E	energy of added particle
[in]	px	x-component of momentum of added particle
[in]	py	y-component of momentum of added particle
[in]	pz	z-component of momentum of added particle
[out]	particles	structure, to which the particle is added

Definition at line 118 of file listmodus.cc.

                                                {
   try {
     ParticleData new_particle =
         create_valid_smash_particle_matching_provided_quantities(
             pdgcode, mass, {t, x, y, z}, {E, px, py, pz}, LList,
             warn_about_mass_discrepancy_, warn_about_off_shell_particles_);
     particles.insert(new_particle);
   } catch (ParticleType::PdgNotFoundFailure &) {
     logg[LList].warn() << "SMASH does not recognize pdg code " << pdgcode
                        << " loaded from file. This particle will be ignored.\n";
   }
 }

◆ is_list()

bool smash::ListModus::is_list ( ) const

inline

Returns: whether the modus is list modus (which is, yes, trivially true)

Definition at line 148 of file listmodus.h.

148 { return true; }

◆ file_has_events_()

bool smash::ListModus::file_has_events_	(	std::filesystem::path	filepath,
		std::streampos	last_position
	)

private

Check if the file given by filepath has events left after streampos last_position.

Parameters

[in]	filepath	Path to file to be checked.
[in]	last_position	Stream position in file after which check is performed

Returns: True if there is at least one event left, false otherwise

Exceptions

runtime_error If file could not be read for whatever reason.

Definition at line 241 of file listmodus.cc.

                                                              {
   std::ifstream ifs{filepath};
   std::string line;
  
   // last event read read at end of file. we know this because errors are
   // handled in next_event
   if (last_position == -1) {
     return false;
   }
   ifs.seekg(last_position);
   // skip over comment lines, assume that a max. of four consecutive comment
   // lines can occur
   int skipped_lines = 0;
   const int max_comment_lines = 4;
   while (std::getline(ifs, line) && line[0] != '#' &&
          skipped_lines++ < max_comment_lines) {
   }
  
   if (ifs.eof()) {
     return false;
   }
  
   if (!ifs.good()) {
     logg[LList].fatal() << "Error while reading "
                         << filepath.filename().native();
     throw std::runtime_error("Error while reading external particle list");
   }
  
   ifs.close();
   return true;
 }

◆ file_path_()

std::filesystem::path smash::ListModus::file_path_ ( std::optional< int > file_id )

private

Return the absolute path of the data file.

If an integer is passed, the filename is constructed using particle_list_filename_or_prefix_ concatenated with the given number, otherwise the file prefix is understood to be the full filename. The file is expected to be in particle_list_file_directory_ folder.

Parameters

[in] file_id An std::optional integer

Returns: Absolute file path to file

Exceptions

runtime_error if file does not exist.

Definition at line 173 of file listmodus.cc.

                                                                 {
   std::string fname = particle_list_filename_or_prefix_ +
                       ((file_id) ? std::to_string(*file_id) : "");
  
   const std::filesystem::path default_path =
       std::filesystem::absolute(particle_list_file_directory_);
  
   const std::filesystem::path fpath = default_path / fname;
  
   logg[LList].debug() << "File: " << std::filesystem::absolute(fpath) << '\n';
  
   if (!std::filesystem::exists(fpath)) {
     logg[LList].fatal()
         << fpath.filename().native() << " does not exist! \n\n"
         << "Usage of smash with external particle lists:\n"
         << "  1. Put the external particle lists in one or more files\n"
         << "     according to the user guide instructions.\n"
         << "  2. Particles info: t x y z mass p0 px py pz pdg ID charge\n"
         << "     in units of: fm fm fm fm GeV GeV GeV GeV GeV none none e\n";
     throw std::runtime_error("External particle list does not exist!");
   }
  
   return fpath;
 }

◆ next_event_()

std::string smash::ListModus::next_event_ ( )

private

Read the next event.

Either from the current file if it has more events or from the next file (with file_id += 1)

Returns: One event as string.

Exceptions

runtime_error If file could not be read for whatever reason.

Definition at line 198 of file listmodus.cc.

                                  {
   const std::filesystem::path fpath = file_path_(file_id_);
   std::ifstream ifs{fpath};
   ifs.seekg(last_read_position_);
  
   if (!file_has_events_(fpath, last_read_position_)) {
     if (file_id_) {
       // Get next file and call this function recursively
       (*file_id_)++;
       last_read_position_ = 0;
       ifs.close();
       return next_event_();
     } else {
       throw std::runtime_error(
           "Attempt to read in next event in Listmodus object but no further "
           "data found in single provided file. Please, check your setup.");
     }
   }
  
   // read one event. events marked by line # event end i in case of Oscar
   // output. Assume one event per file for all other output formats
   std::string event_string;
   const std::string needle = "end";
   std::string line;
   while (getline(ifs, line)) {
     if (line.find(needle) == std::string::npos) {
       event_string += line + "\n";
     } else {
       break;
     }
   }
  
   if (!ifs.eof() && (ifs.fail() || ifs.bad())) {
     logg[LList].fatal() << "Error while reading " << fpath.filename().native();
     throw std::runtime_error("Error while reading external particle list");
   }
   // save position for next event read
   last_read_position_ = ifs.tellg();
   ifs.close();
  
   return event_string;
 }

Member Data Documentation

◆ start_time_

double smash::ListModus::start_time_ = 0.

protected

Starting time for the List; changed to the earliest formation time.

Definition at line 152 of file listmodus.h.

◆ particle_list_file_directory_

std::string smash::ListModus::particle_list_file_directory_

private

File directory of the particle list.

Definition at line 193 of file listmodus.h.

◆ particle_list_filename_or_prefix_

std::string smash::ListModus::particle_list_filename_or_prefix_

private

Prefix of the file(s) containing the particle list.

If the user want to use a single file without numbering, this will contain the full filename.

Definition at line 199 of file listmodus.h.

◆ file_id_

std::optional<int> smash::ListModus::file_id_

private

The id of the current file.

Definition at line 202 of file listmodus.h.

◆ event_id_

int smash::ListModus::event_id_

private

The unique id of the current event.

Definition at line 205 of file listmodus.h.

◆ last_read_position_

std::streampos smash::ListModus::last_read_position_ = 0

private

Last read position in current file.

Definition at line 208 of file listmodus.h.

◆ warn_about_mass_discrepancy_

bool smash::ListModus::warn_about_mass_discrepancy_ = true

private

Auxiliary flag to warn about mass-discrepancies only once per instance.

Definition at line 211 of file listmodus.h.

◆ warn_about_off_shell_particles_

bool smash::ListModus::warn_about_off_shell_particles_ = true

private

Auxiliary flag to warn about off-shell particles only once per instance.

Definition at line 213 of file listmodus.h.

The documentation for this class was generated from the following files:

src/include/smash/listmodus.h
src/listmodus.cc

Classes

Public Member Functions

Protected Attributes

Private Member Functions

Private Attributes

Friends

Constructor & Destructor Documentation

◆ ListModus() [1/2]

◆ ListModus() [2/2]

Member Function Documentation

◆ initial_conditions()

◆ backpropagate_to_same_time()

◆ try_create_particle()

◆ is_list()

◆ file_has_events_()

◆ file_path_()

◆ next_event_()

Member Data Documentation

◆ start_time_

◆ particle_list_file_directory_

◆ particle_list_filename_or_prefix_

◆ file_id_

◆ event_id_

◆ last_read_position_

◆ warn_about_mass_discrepancy_

◆ warn_about_off_shell_particles_