DecayTreeFitter on filtered selection

This example shows how to:

1. select two detached opposite-charge muons

2. create a tuple of the selected candidates

3. filter to select only the particles of interest

4. run DecayTreeFitterAlg and stores some output

import Functors as F
from DaVinci import Options, make_config
from DaVinci.algorithms import create_lines_filter
from DecayTreeFitter import DecayTreeFitter
from FunTuple import FunctorCollection
from FunTuple import FunTuple_Particles as Funtuple
from PyConf.reading import get_particles


def main(options: Options):
    # fields for FunTuple
    fields = {}
    fields["B0"] = "[B0 -> D_s- K+]CC"
    fields["Ds"] = "[B0 -> ^D_s- K+]CC"
    fields["K"] = "[B0 -> D_s- ^K+]CC"

    spruce_line = "SpruceB2OC_BdToDsmK_DsmToHHH_FEST_Line"
    data_filtered = get_particles(f"/Event/Spruce/{spruce_line}/Particles")

    # DecayTreeFitter Algorithm.
    DTF = DecayTreeFitter(
        name="DTF_filtered",
        input_particles=data_filtered,
        mass_constraints=["D_s-"],
    )

    # make collection of functors for all particles
    variables_all = FunctorCollection(
        {
            "THOR_P": F.P,
            "THOR_PT": F.PT,
            "THOR_MASS": F.MASS,
        }
    )

    # make collection of functors for Ds meson
    variables_ds = FunctorCollection(
        {
            "DTF_PT": DTF(F.PT),
            "DTF_MASS": DTF(F.MASS),
            # Important note: specify an invalid value for integer functors if there exists no truth info.
            #                 The invalid value for floating point functors is set to nan.
            "DTF_CHILD1_ID": F.VALUE_OR(0) @ DTF(F.CHILD(1, F.PARTICLE_ID)),
            "DTF_CHILD1_MASS": DTF(F.CHILD(1, F.MASS)),
        }
    )

    # associate FunctorCollection to field (branch) name
    variables = {"ALL": variables_all, "Ds": variables_ds}

    filter_data = create_lines_filter("SpruceFilter", lines=[f"{spruce_line}"])

    # Configure Funtuple algorithm
    tuple_data = Funtuple(
        name="B0DsK_Tuple",
        tuple_name="DecayTree",
        fields=fields,
        variables=variables,
        inputs=data_filtered,
    )

    return make_config(options, [filter_data, tuple_data])

To run the example:

lbexec DaVinciExamples.tupling.DTF_filtered:main $DAVINCIEXAMPLESROOT/example_data/Spruce_all_lines_dst.yaml+$DAVINCIEXAMPLESROOT/example_options/example_tupling_DTF_filtered.yaml

For reference, these are the options of this example

input_files:
- root://eoslhcb.cern.ch//eos/lhcb/wg/dpa/wp3/tests/spruce_all_lines_realtimereco_newPacking_newDst.dst
input_manifest_file: root://eoslhcb.cern.ch//eos/lhcb/wg/dpa/wp3/tests/spruce_all_lines_realtime_newPacking_newDst.tck.json
input_type: ROOT
simulation: true
conddb_tag: sim-20171127-vc-md100
dddb_tag: dddb-20171126
conditions_version: master
geometry_version: run3/trunk
lumi: False
write_fsr: False
histo_file: sprucing_histos.root
ntuple_file: sprucing_tuple.root
input_raw_format: 0.5
input_process: Spruce
persistreco_version: 0.0

evt_max: 10
histo_file: DV-example-tupling-DTF-his-filtered.root
ntuple_file: DV-example-tupling-DTF-ntp-filtered.root