Project.toml

@@ -6,6 +6,7 @@ version = "0.1.0"
 [deps]
 AccurateArithmetic = "22286c92-06ac-501d-9306-4abd417d9753"
 CUDA = "052768ef-5323-5732-b1bb-66c8b64840ba"
+Combinatorics = "861a8166-3701-5b0c-9a16-15d98fcdc6aa"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 JuliaFormatter = "98e50ef6-434e-11e9-1051-2b60c6c9e899"

src/graph/properties.jl

@@ -7,7 +7,8 @@ function get_properties(graph::DAG)
     # make sure the graph is fully generated
     apply_all!(graph)
 
-    if (graph.properties.computeEffort == 0.0)
+    # TODO: tests stop working without the if condition, which means there is probably a bug in the lazy evaluation and in the tests
+    if (graph.properties.computeEffort <= 0.0)
         graph.properties = GraphProperties(graph)
     end
 

src/models/qed/diagrams.jl

@@ -1,3 +1,4 @@
+using Combinatorics
 
 import Base.copy
 import Base.hash
@@ -265,11 +266,12 @@ function add_vertex!(fd::FeynmanDiagram, vertex::FeynmanVertex)
     end
 
     if !can_apply_vertex(get_particles(fd), vertex)
-        #@assert false "Can't add vertex $vertex to diagram"
+        @assert false "Can't add vertex $vertex to diagram $(get_particles(fd))"
     end
 
     push!(fd.vertices, Set{FeynmanVertex}())
     push!(fd.vertices[end], vertex)
+
     fd.type_ids[vertex.out.particle] += 1
 
     return nothing
@@ -437,12 +439,95 @@ function remove_duplicates(compare_set::Set{FeynmanDiagram})
     return result
 end
 
+"""
+    is_compton(fd::FeynmanDiagram)
+
+Returns true iff the given feynman diagram is an (empty) diagram of a compton process like ke->k^ne
+"""
+function is_compton(fd::FeynmanDiagram)
+    return fd.type_ids[FermionStateful{Incoming, SpinUp}] == 1 &&
+           fd.type_ids[FermionStateful{Outgoing, SpinUp}] == 1 &&
+           fd.type_ids[PhotonStateful{Incoming, PolX}] == 1 &&
+           fd.type_ids[PhotonStateful{Outgoing, PolX}] >= 1
+end
+
+"""
+    n_photon_compton_diagrams(n::Int)
+
+Special case diagram generation for n-Photon Compton processes, i.e., processes of the form ke->k^ne
+"""
+function n_photon_compton_diagram(n::Int)
+    inEl = FeynmanParticle(FermionStateful{Incoming, SpinUp}, 1)
+    outEl = FeynmanParticle(FermionStateful{Outgoing, SpinUp}, 1)
+
+    photons = [FeynmanParticle(PhotonStateful{Outgoing, PolX}, i) for i in 1:n]
+    push!(photons, FeynmanParticle(PhotonStateful{Incoming, PolX}, 1))
+
+    perms = permutations([i for i in 1:length(photons)])
+
+    diagrams = Vector{FeynmanDiagram}()
+    for order in perms
+        new_diagram = FeynmanDiagram(
+            [],
+            missing,
+            [inEl, outEl, photons...],
+            Dict{Type, Int64}(
+                FermionStateful{Incoming, SpinUp} => 1,
+                FermionStateful{Outgoing, SpinUp} => 1,
+                PhotonStateful{Incoming, PolX} => 1,
+                PhotonStateful{Outgoing, PolX} => n,
+            ),
+        )
+
+        left_index = 1
+        right_index = length(order)
+
+        iterations = 1
+
+        while left_index <= right_index
+            # left side
+            v_left = FeynmanVertex(
+                FeynmanParticle(FermionStateful{Incoming, SpinUp}, iterations),
+                photons[order[left_index]],
+                FeynmanParticle(FermionStateful{Incoming, SpinUp}, iterations + 1),
+            )
+            left_index += 1
+            add_vertex!(new_diagram, v_left)
+
+            if (left_index > right_index)
+                break
+            end
+
+            # right side
+            v_right = FeynmanVertex(
+                FeynmanParticle(FermionStateful{Outgoing, SpinUp}, iterations),
+                photons[order[right_index]],
+                FeynmanParticle(FermionStateful{Outgoing, SpinUp}, iterations + 1),
+            )
+            right_index -= 1
+            add_vertex!(new_diagram, v_right)
+
+            iterations += 1
+        end
+
+        @assert possible_tie(new_diagram) !== missing
+        add_tie!(new_diagram, possible_tie(new_diagram))
+        push!(diagrams, new_diagram)
+    end
+
+    return diagrams
+end
+
 """
     gen_diagrams(fd::FeynmanDiagram)
 
 From a given feynman diagram in its initial state, e.g. when created through the [`FeynmanDiagram(pd::ProcessDescription)`](@ref) constructor, generate and return all possible [`FeynmanDiagram`](@ref)s that describe that process.
 """
 function gen_diagrams(fd::FeynmanDiagram)
+    if is_compton(fd)
+        return n_photon_compton_diagram(fd.type_ids[PhotonStateful{Outgoing, PolX}])
+    end
+
     working = Set{FeynmanDiagram}()
     results = Set{FeynmanDiagram}()