Visualize decay topologies¶

The io module allows you to convert StateTransitionGraph and Topology instances to DOT language with convert_to_dot(). You can visualize its output with third-party libraries, such as Graphviz. This is particularly useful after running find_solutions(), which produces a Result object with a list of StateTransitionGraph instances (see Create amplitude models).

Topologies¶

First of all, here are is an example of how to visualize a group of Topology instances. We use create_isobar_topologies() and create_n_body_topology() to create a few standard topologies.

import graphviz
from expertsystem import io
from expertsystem.reaction.topology import (
    create_isobar_topologies,
    create_n_body_topology,
)

topology = create_n_body_topology(2, 4)
graphviz.Source(io.convert_to_dot(topology))

Note the IDs of the nodes is also rendered if there is more than node:

topologies = create_isobar_topologies(4)
graphviz.Source(io.convert_to_dot(topologies))

This can be turned off with the arguments of convert_to_dot():

topologies = create_isobar_topologies(3)
graphviz.Source(io.convert_to_dot(topologies, render_node=False))

`StateTransitionGraph`s¶

Here, we’ll visualize the allowed transitions for the decay \(\psi' \to \gamma\eta\eta\) as an example.

import expertsystem as es

result = es.reaction.generate(
    initial_state="psi(2S)",
    final_state=["gamma", "eta", "eta"],
    allowed_interaction_types="EM",
)

Convert to DOT and visualize¶

As noted in 1.3. Find solutions, the transitions contain all spin projection combinations (which is necessary for the amplitude module). It is possible to convert all these solutions to DOT language with convert_to_dot(). To avoid visualizing all solutions, we just take a subset of the transitions:

dot_source = es.io.convert_to_dot(
    result.transitions[::50][:3]
)  # just some selection

This str of DOT language for the list of StateTransitionGraph instances can then be visualized with a third-party library, for instance, with graphviz.Source:

import graphviz

graphviz.Source(dot_source)

You can also serialize the DOT string to file with io.write. The file extension for a DOT file is .gv:

es.io.write(result.transitions, "decay_topologies_with_spin.gv")

Collapse graphs¶

Since this list of all possible spin projections transitions is rather long, it is often useful to make use of the get_particle_graphs() or collapse_graphs() methods to bundle comparable graphs. First, get_particle_graphs() allows one collapse (ignore) the spin projections (we again show a selection only):

graphs = result.get_particle_graphs()
dot_source = es.io.convert_to_dot(graphs[:3], render_edge_id=False)
graphviz.Source(dot_source)

Note

By default, .convert_to_dot renders edge IDs, because they represent the (final) state IDs as well. In the example above, we switched this off.

If that list is still too much, there is collapse_graphs(), which bundles all graphs with the same final state groupings:

graphs = result.collapse_graphs()
dot_source = es.io.convert_to_dot(graphs)
graphviz.Source(dot_source)

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