smash::decaytree::Node Struct Reference

Node of a decay tree, representing a possible action (2-to-2 or 1-to-2).

This data structure can be used to build a tree going from the initial state (a collision of two particles) to all possible final states by recursively performing all possible decays. The tree can be used to calculate the final state cross sections.

The initial actions are 2-to-2 or 2-to-1 scatterings, all other actions are 1-to-2 decays.

Definition at line 596 of file scatteractionsfinder.cc.

Collaboration diagram for smash::decaytree::Node:

Public Member Functions
	Node (const Node &)=delete
	Cannot be copied. More...
	Node (Node &&)=default
	Move constructor. More...
	Node (const std::string &name, double weight, ParticleTypePtrList &&initial_particles, ParticleTypePtrList &&final_particles, ParticleTypePtrList &&state, std::vector< Node > &&children)
Node &	add_action (const std::string &name, double weight, ParticleTypePtrList &&initial_particles, ParticleTypePtrList &&final_particles)
	Add an action to the children of this node. More...
void	print () const
	Print the decay tree starting with this node. More...
std::vector< FinalStateCrossSection >	final_state_cross_sections () const

Public Attributes
std::string	name_
	Name for printing. More...
double	weight_
	Weight (cross section or branching ratio). More...
ParticleTypePtrList	initial_particles_
	Initial-state particle types in this action. More...
ParticleTypePtrList	final_particles_
	Final-state particle types in this action. More...
ParticleTypePtrList	state_
	Particle types corresponding to the global state after this action. More...
std::vector< Node >	children_
	Possible actions after this action. More...

Private Member Functions
void	print_helper (uint64_t depth) const
	Internal helper function for print, to be called recursively to print all nodes. More...
void	final_state_cross_sections_helper (uint64_t depth, std::vector< FinalStateCrossSection > &result, const std::string &name, double weight, bool show_intermediate_states=false) const
	Internal helper function for final_state_cross_sections, to be called recursively to calculate all final-state cross sections. More...

Constructor & Destructor Documentation

Node() [1/3]

smash::decaytree::Node::Node ( const Node &  )

delete

Cannot be copied.

Node() [2/3]

smash::decaytree::Node::Node ( Node &&  )

default

Move constructor.

Node() [3/3]

smash::decaytree::Node::Node ( const std::string &  name, double  weight, ParticleTypePtrList &&  initial_particles, ParticleTypePtrList &&  final_particles, ParticleTypePtrList &&  state, std::vector< Node > &&  children  )

inline

Returns

A new decay tree node.

Parameters

name	Name for printing.
weight	Cross section or branching ratio.
initial_particles	Initial-state particle types in this node.
final_particles	Final-state particle types in this node.
state	Curent particle types of the system.
children	Possible actions after this action.

Definition at line 631 of file scatteractionsfinder.cc.

      : name_(name),
        weight_(weight),
        initial_particles_(std::move(initial_particles)),
        final_particles_(std::move(final_particles)),
        state_(std::move(state)),
        children_(std::move(children)) {}

Member Function Documentation

add_action()

Node& smash::decaytree::Node::add_action ( const std::string &  name, double  weight, ParticleTypePtrList &&  initial_particles, ParticleTypePtrList &&  final_particles  )

inline

Add an action to the children of this node.

The current particle state of the new action is automatically calculated.

Parameters

name	Name of the action used for output.
weight	Cross section/branching ratio of the action.
initial_particles	Initial-state particle types of the action.
final_particles	Final-state particle types of the action.

Returns

Newly added node by reference.

Definition at line 653 of file scatteractionsfinder.cc.

                                                          {
    // Copy parent state and update it.
    ParticleTypePtrList state(state_);
    for (const auto& p : initial_particles) {
      state.erase(std::find(state.begin(), state.end(), p));
    }
    for (const auto& p : final_particles) {
      state.push_back(p);
    }
    // Sort the state to normalize the output.
    std::sort(state.begin(), state.end(),
              [](ParticleTypePtr a, ParticleTypePtr b) {
                return a->name() < b->name();
              });
    // Push new node to children.
    Node new_node(name, weight, std::move(initial_particles),
                  std::move(final_particles), std::move(state), {});
    children_.emplace_back(std::move(new_node));
    return children_.back();
  }

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print()

void smash::decaytree::Node::print ( ) const

inline

Print the decay tree starting with this node.

Definition at line 677 of file scatteractionsfinder.cc.

{ print_helper(0); }

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final_state_cross_sections()

std::vector<FinalStateCrossSection> smash::decaytree::Node::final_state_cross_sections ( ) const

inline

Returns

Final-state cross sections.

Definition at line 682 of file scatteractionsfinder.cc.

                                                                       {
    std::vector<FinalStateCrossSection> result;
    final_state_cross_sections_helper(0, result, "", 1.);
    return result;
  }

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print_helper()

void smash::decaytree::Node::print_helper ( uint64_t  depth ) const

inlineprivate

Internal helper function for print, to be called recursively to print all nodes.

Parameters

depth

Recursive call depth.

Definition at line 695 of file scatteractionsfinder.cc.

                                          {
    for (uint64_t i = 0; i < depth; i++) {
      std::cout << " ";
    }
    std::cout << name_ << " " << weight_ << std::endl;
    for (const auto& child : children_) {
      child.print_helper(depth + 1);
    }
  }

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final_state_cross_sections_helper()

void smash::decaytree::Node::final_state_cross_sections_helper ( uint64_t  depth, std::vector< FinalStateCrossSection > &  result, const std::string &  name, double  weight, bool  show_intermediate_states = false  ) const

inlineprivate

Internal helper function for final_state_cross_sections, to be called recursively to calculate all final-state cross sections.

Parameters

depth	Recursive call depth.
result	Pairs of process names and exclusive cross sections.
name	Current name.
weight	current Weight/cross section.
show_intermediate_states	Whether intermediate states should be shown.

Definition at line 716 of file scatteractionsfinder.cc.

                                                   {
    // The first node corresponds to the total cross section and has to be
    // ignored. The second node corresponds to the partial cross section. All
    // further nodes correspond to branching ratios.
    if (depth > 0) {
      weight *= weight_;
    }
 
    std::string new_name;
    double mass = 0.;
 
    if (show_intermediate_states) {
      new_name = name;
      if (!new_name.empty()) {
        new_name += "->";
      }
      new_name += name_;
      new_name += "{";
    } else {
      new_name = "";
    }
    for (const auto& s : state_) {
      new_name += s->name();
      mass += s->mass();
    }
    if (show_intermediate_states) {
      new_name += "}";
    }
 
    if (children_.empty()) {
      result.emplace_back(FinalStateCrossSection(new_name, weight, mass));
      return;
    }
    for (const auto& child : children_) {
      child.final_state_cross_sections_helper(depth + 1, result, new_name,
                                              weight, show_intermediate_states);
    }
  }

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Member Data Documentation

name_

std::string smash::decaytree::Node::name_

Name for printing.

Definition at line 599 of file scatteractionsfinder.cc.

weight_

double smash::decaytree::Node::weight_

Weight (cross section or branching ratio).

Definition at line 602 of file scatteractionsfinder.cc.

initial_particles_

ParticleTypePtrList smash::decaytree::Node::initial_particles_

Initial-state particle types in this action.

Definition at line 605 of file scatteractionsfinder.cc.

final_particles_

ParticleTypePtrList smash::decaytree::Node::final_particles_

Final-state particle types in this action.

Definition at line 608 of file scatteractionsfinder.cc.

state_

ParticleTypePtrList smash::decaytree::Node::state_

Particle types corresponding to the global state after this action.

Definition at line 611 of file scatteractionsfinder.cc.

children_

std::vector<Node> smash::decaytree::Node::children_

Possible actions after this action.

Definition at line 614 of file scatteractionsfinder.cc.

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The documentation for this struct was generated from the following file:

• src/scatteractionsfinder.cc