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File indexing completed on 2021-02-14 14:28:13

0001 #ifndef MultiTrackVertexLinkKinematicConstraint_H
0002 #define MultiTrackVertexLinkKinematicConstraint_H
0003 
0004 #include "RecoVertex/KinematicFitPrimitives/interface/MultiTrackKinematicConstraint.h"
0005 #include "RecoVertex/KinematicFitPrimitives/interface/KinematicState.h"
0006 #include "DataFormats/CLHEP/interface/AlgebraicObjects.h"
0007 
0008 /**
0009  *  This is an specialized version of MultiTrackVertexLinkKinematicConstraint.
0010  *  It constraints the sum of 4-vectors combined at a secondary vertex to be in parallel to the vertex link
0011  *  after considering the helix bend of the summed vector when propagating to the primary vertex.
0012  *
0013  *  Lars Perchalla, Philip Sauerland, July 2010
0014  */
0015 //mother constructed from daughters. including propagation in field.
0016 
0017 class MultiTrackVertexLinkKinematicConstraint : public MultiTrackKinematicConstraint {
0018 public:
0019   MultiTrackVertexLinkKinematicConstraint(GlobalPoint& ref) : refPoint(ref) {}
0020 
0021   /**
0022      * Returns a vector of values of constraint
0023      * equations at the point where the input
0024      * particles are defined.
0025      */
0026   AlgebraicVector value(const std::vector<KinematicState>& states, const GlobalPoint& point) const override;
0027 
0028   /**
0029      * Returns a matrix of derivatives of
0030      * constraint equations w.r.t. 
0031      * particle parameters
0032      */
0033   AlgebraicMatrix parametersDerivative(const std::vector<KinematicState>& states,
0034                                        const GlobalPoint& point) const override;
0035 
0036   /**
0037      * Returns a matrix of derivatives of
0038      * constraint equations w.r.t. 
0039      * vertex position
0040      */
0041   AlgebraicMatrix positionDerivative(const std::vector<KinematicState>& states,
0042                                      const GlobalPoint& point) const override;
0043 
0044   /**
0045      * Number of equations per track used for the fit
0046      */
0047   int numberOfEquations() const override;
0048 
0049   MultiTrackVertexLinkKinematicConstraint* clone() const override {
0050     return new MultiTrackVertexLinkKinematicConstraint(*this);
0051   }
0052 
0053 private:
0054   GlobalPoint refPoint;
0055 };
0056 #endif