Class Acts::IterativeVertexFinder
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template<typename vfitter_t, typename sfinder_t>
class IterativeVertexFinder Implements an iterative vertex finder.
Brief description of the algorithm implemented: Iterative vertex finder which iteratively finds and fits vertices:
A list of seed tracks (
seedTracks
, which is the same as the input track list to the finder at the very first iteration) is used to retrieve a single vertex seed using the ZScanVertexFinder.All tracks compatible with the current vertex seed are kept and used for fitting the single vertex. 3.1 If the vertex is a ‘good’ vertex (i.e. meets requirements) and no track reassignment after first fit is required, go to step 4. If vertex is not a good vertex, remove all tracks in tracksToFit from seedTracks. 3.2 If vertex meets requirements and track reassignment after first fit is required, iterate over all previously found vertices (“old vertex”) and over all their tracksAtVertex. Compare compatibility of each track with old vertex and current vertex. If track is more compatible with current vertex, remove track from old vertex, put track back to tracksToFit and refit current vertex with additional track.
If good vertex,
removeUsedCompatibleTracks
method is called, which removes all used tracks that are compatible with the fitted vertex fromtracksToFit
andseedTracks
. It also removes outliers tracks from tracksAtVertex if not compatible.Add vertex to vertexCollection
Repeat until no seedTracks are left or max. number of vertices found
- Template Parameters
vfitter_t – Vertex fitter type
sfinder_t – Seed finder type
Public Types
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using IPEstimator = ImpactPointEstimator<InputTrack_t, Propagator_t>
Public Functions
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inline IterativeVertexFinder(Config &cfg, std::function<BoundTrackParameters(InputTrack_t)> func, std::unique_ptr<const Logger> logger = getDefaultLogger("IterativeVertexFinder", Logging::INFO))
Constructor for user-defined InputTrack_t type =! BoundTrackParameters.
- Parameters
cfg – Configuration object
func – Function extracting BoundTrackParameters from InputTrack_t object
logger – The logging instance
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template<typename T = InputTrack_t, std::enable_if_t<std::is_same<T, BoundTrackParameters>::value, int> = 0>
inline IterativeVertexFinder(Config &cfg, std::unique_ptr<const Logger> logger = getDefaultLogger("IterativeVertexFinder", Logging::INFO)) Constructor used if InputTrack_t type == BoundTrackParameters.
- Parameters
cfg – Configuration object
logger – The logging instance
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Result<std::vector<Vertex<InputTrack_t>>> find(const std::vector<const InputTrack_t*> &trackVector, const VertexingOptions<InputTrack_t> &vertexingOptions, State &state) const
Finds vertices corresponding to input trackVector.
- Parameters
trackVector – Input tracks
vertexingOptions – Vertexing options
state – State for fulfilling interfaces
- Returns
Collection of vertices found by finder
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struct Config
Configuration struct.
Public Functions
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inline Config(const vfitter_t &fitter, Linearizer_t lin, sfinder_t sfinder, const IPEstimator &est)
Config constructor.
- Parameters
fitter – Vertex fitter
lin – Track linearizer
sfinder – The seed finder
est – ImpactPointEstimator
Public Members
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bool createSplitVertices = false
Assign a certain fraction of compatible tracks to a different (so-called split) vertex if boolean is set to true.
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double cutOffTrackWeight = 0.01
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double cutOffTrackWeightReassign = 1
If
reassignTracksAfterFirstFit
is set this threshold will be used to decide if a track should be checked for reassignment to other vertices.
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bool doMaxTracksCut = false
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IPEstimator ipEst
ImpactPointEstimator.
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Linearizer_t linearizer
Linearized track factory.
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double maximumChi2cutForSeeding = 36.
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int maxTracks = 5000
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int maxVertices = 50
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bool reassignTracksAfterFirstFit = false
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double significanceCutSeeding = 10
Vertex finder configuration variables.
Tracks that are within a distance of
significanceCutSeeding * sqrt(sigma(d0)^2+sigma(z0)^2)
are considered compatible with the vertex.
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int splitVerticesTrkInvFraction = 2
Inverse of the fraction of tracks that will be assigned to the split vertex.
E.g., if splitVerticesTrkInvFraction = 2, about 50% of compatible tracks will be assigned to the split vertex.
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inline Config(const vfitter_t &fitter, Linearizer_t lin, sfinder_t sfinder, const IPEstimator &est)
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struct State
State struct.
Public Functions
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inline State(const MagneticFieldProvider &field, const Acts::MagneticFieldContext &magContext)
Public Members
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IPEstimator::State ipState
The IP estimator state.
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Linearizer_t::State linearizerState
The inearizer state.
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inline State(const MagneticFieldProvider &field, const Acts::MagneticFieldContext &magContext)