import pylhe
from feynml.feynmandiagram import FeynmanDiagram
from feynml.feynml import FeynML, Head, Meta
from feynml.leg import Leg
from feynml.propagator import Propagator
from feynml.vertex import Vertex
from .util import leg_id_wrap, propagator_id_wrap, vertex_id_wrap
# TODO add momenta?
[docs]def lhe_event_to_feynman(event: pylhe.LHEEvent) -> FeynmanDiagram:
fd = FeynmanDiagram()
hp = Vertex(id=vertex_id_wrap(0))
fd.add(hp)
hpids = []
for lhe_id, p in enumerate(event.particles):
lhe_id += 1
pdgid = round(p.id)
if p.status == -1:
# outgoing Leg
fd.add(
Leg(
id=leg_id_wrap(lhe_id),
pdgid=pdgid,
target=vertex_id_wrap(0),
sense="incoming",
)
)
hpids.append(lhe_id)
for lhe_id, p in enumerate(event.particles):
lhe_id += 1
pdgid = round(p.id)
if p.mother1 in hpids and p.mother2 in hpids:
if p.status == 1:
# outgoing Leg
fd.add(
Leg(
id=leg_id_wrap(lhe_id),
pdgid=pdgid,
target=vertex_id_wrap(0),
sense="outgoing",
)
)
if p.status == 2:
# Propagator
# create a new vertex...
fd.add(Vertex(id=vertex_id_wrap(lhe_id)))
fd.add(
Propagator(
id=leg_id_wrap(lhe_id),
pdgid=pdgid,
source=vertex_id_wrap(0),
target=vertex_id_wrap(lhe_id),
)
)
nvertices = 1 # the hard process vertex
while nvertices != len(fd.vertices):
nvertices = len(fd.vertices)
for lhe_id, p in enumerate(event.particles):
lhe_id += 1
pdgid = round(p.id)
# print("Candidate particle: ", lhe_id, p.id, p.status, p.mother1, p.mother2)
for v in fd.vertices:
# print("1Candidate particle: ", lhe_id, p.id, p.status, p.mother1, p.mother2)
if (
vertex_id_wrap(p.mother1) == v.id
and vertex_id_wrap(p.mother2) == v.id
): # TODO this will not cover all cases, i.e. when there are more than one vertex in the decay chain
# print("2Candidate particle: ", lhe_id, p.id, p.status, p.mother1, p.mother2)
if p.status == 1:
# check if the particle is already in the diagram
if not leg_id_wrap(lhe_id) in [l.id for l in fd.legs]:
fd.add(
Leg(
id=leg_id_wrap(lhe_id),
pdgid=pdgid,
target=v.id,
sense="outgoing",
)
)
if p.status == 2:
# Propagator
# create a new vertex... , this will result in rerunning the loop
if not vertex_id_wrap(lhe_id) in [l.id for l in fd.vertices]:
fd.add(Vertex(id=vertex_id_wrap(lhe_id)))
fd.add(
Propagator(
id=leg_id_wrap(lhe_id),
pdgid=pdgid,
source=v.id,
target=vertex_id_wrap(lhe_id),
)
)
assert len(fd.legs) + len(fd.propagators) == len(
event.particles
), "Not all particles are accounted for!\nlegs = {}\npropagators = {}\nparticles = {}".format(
len(fd.legs), len(fd.propagators), len(event.particles)
)
return fd
[docs]def lhe_to_feynml(
lhe_file: str,
creator="pyfeyn2",
tool="pyfeyn2.interface.hepmc",
title="",
description="",
) -> FeynML:
fds = []
events = pylhe.read_lhe_with_attributes(lhe_file)
for event in events:
fds.append(lhe_event_to_feynman(event))
return FeynML(
diagrams=fds,
head=Head(
metas=[
Meta(name="creator", content=creator),
Meta(name="tool", content=tool),
Meta(name="description", content=description),
Meta(name="title", content=title),
]
),
)