HitInHyperBox Class Reference

An algorithm to check if a hit is contained in a hyperbolic cosine hough box. More...

#include <HitInHyperBox.h>

Public Types
using	HoughBox = Box< DiscreteQ, DiscreteP, DiscreteZ0 >
	Hough space is 3D with axes q, p, z0 as described above.

Public Member Functions
Weight	operator() (const CDCRecoHit3D &recoHit, const HoughBox *hyperBox)
	Returns weight of the hit for the given hough box; in this algorithm - 1 if hit inside the box, NaN otherwise.

Static Public Member Functions
static bool	compareDistances (const HoughBox &hyperBox, const CDCRecoHit3D &lhsRecoHit, const CDCRecoHit3D &rhsRecoHit)
	Compares distances from two hits to the track represented by the given box.
static float	centerX (const HoughBox &hyperBox)
	Returns center value of the box along first (Q) axis.
static float	centerY (const HoughBox &hyperBox)
	Returns center value of the box along second (P) axis.
static float	centerZ (const HoughBox &hyperBox)
	Returns center value of the box along third (Z0) axis.
static float	deltaX (const HoughBox &hyperBox)
	Returns half width of the box along first (Q) axis.
static const char *	debugLine ()
	ROOT expression of the track hypothesis.

Static Private Member Functions
static double	catZ (const double q, const double p, const double R)
	Returns z(R) for the catenary with parameters q = E/p_t and p = p_z/E.

Detailed Description

An algorithm to check if a hit is contained in a hyperbolic cosine hough box.

The exact parameterization is z(R) = 1 / mu * (sqrt(1 - p * p) * cosh(R * mu / q + arcsinh(p / sqrt(1 - p * p))) - 1) + z0

q is p_t / E - transverse fraction of energy p is p_z / E - longitudinal fraction of energy mu is gcB / E - inverse of scale; ranges from 0.0375 for E=6GeV, g=0.5 to 2.25 for E=1GeV, g=5.0 z0 is z at R=0 z and R are in units of CDC size

If we apply a constraint z0=0, The tree will not perform well as mu is highly correlated to q (and p)

Instead we relax z0=0 and apply mu=q Then for a better continuity around g=0 (sign flip), we take 1/q as new q

Resulting parameterization is z(R) = q * (sqrt(1 - p * p) * cosh(R + arcsinh(p / sqrt(1 - p * p))) - 1) + z0 Which can still provide reasonable fits.

Additionally, box edges are behaving more or less on same scale near origin and near edges of CDC if z(R) = +-dQ + 1 / (q +- dQ) * (sqrt(1 - p * p) * cosh(R + arcsinh(p / sqrt(1 - p * p))) - 1) + z0

Definition at line 52 of file HitInHyperBox.h.

Member Typedef Documentation

HoughBox

using HoughBox = Box<DiscreteQ, DiscreteP, DiscreteZ0>

Hough space is 3D with axes q, p, z0 as described above.

Definition at line 56 of file HitInHyperBox.h.

Member Function Documentation

catZ()

static double catZ ( const double  q, const double  p, const double  R  )

inlinestaticprivate

Returns z(R) for the catenary with parameters q = E/p_t and p = p_z/E.

Definition at line 106 of file HitInHyperBox.h.

      {
        //100 here is a reference  - size of CDC in cm
        return 100.0 * Unit::cm * q * (std::sqrt(1 - p * p) * std::cosh(R / (100.0 * Unit::cm) + std::asinh(p / std::sqrt(1 - p * p))) - 1);
      }

centerX()

static float centerX ( const HoughBox &  hyperBox )

inlinestatic

Returns center value of the box along first (Q) axis.

Definition at line 114 of file HitInHyperBox.h.

      {
        return *(hyperBox.getCenter<0>());
      }

centerY()

static float centerY ( const HoughBox &  hyperBox )

inlinestatic

Returns center value of the box along second (P) axis.

Definition at line 120 of file HitInHyperBox.h.

      {
        return *(hyperBox.getCenter<1>());
      }

centerZ()

static float centerZ ( const HoughBox &  hyperBox )

inlinestatic

Returns center value of the box along third (Z0) axis.

Definition at line 126 of file HitInHyperBox.h.

      {
        return *(hyperBox.getCenter<2>());
      }

compareDistances()

static bool compareDistances ( const HoughBox &  hyperBox, const CDCRecoHit3D &  lhsRecoHit, const CDCRecoHit3D &  rhsRecoHit  )

inlinestatic

Compares distances from two hits to the track represented by the given box.

The comparison is done based on reconstructed Z coordinates of hits and track Z position.

Definition at line 86 of file HitInHyperBox.h.

      {
        const float centerQ = *(hyperBox.getCenter<0>());
        const float centerP = *(hyperBox.getCenter<1>());
        const float centerZ0 = *(hyperBox.getCenter<2>());
 
        const double lhsZ = lhsRecoHit.getRecoZ();
        const double rhsZ = rhsRecoHit.getRecoZ();
 
        const double lhsS = lhsRecoHit.getArcLength2D();
        const double rhsS = rhsRecoHit.getArcLength2D();
 
        const double lhsZDistance = catZ(centerQ, centerP, lhsS) + centerZ0 - lhsZ;
        const double rhsZDistance = catZ(centerQ, centerP, rhsS) + centerZ0 - rhsZ;
 
        return lhsZDistance < rhsZDistance;
      }

debugLine()

static const char * debugLine ( )

inlinestatic

ROOT expression of the track hypothesis.

Definition at line 140 of file HitInHyperBox.h.

{ return "100.0 * [0] * (TMath::Sqrt(1 - [1] * [1]) * TMath::CosH(x / 100.0 + TMath::ASinH([1] / TMath::Sqrt(1 - [1] * [1]))) - 1) + [2]";}

deltaX()

static float deltaX ( const HoughBox &  hyperBox )

inlinestatic

Returns half width of the box along first (Q) axis.

Definition at line 132 of file HitInHyperBox.h.

      {
        const float lowerQ = *(hyperBox.getLowerBound<DiscreteQ>()); //DiscreteValue is based on std::vector<T>::const_iterator
        const float upperQ = *(hyperBox.getUpperBound<DiscreteQ>());
        return 0.5 * (upperQ - lowerQ);
      }

operator()()

Weight operator() ( const CDCRecoHit3D &  recoHit, const HoughBox *  hyperBox  )

inline

Returns weight of the hit for the given hough box; in this algorithm - 1 if hit inside the box, NaN otherwise.

Definition at line 59 of file HitInHyperBox.h.

      {
        const float lowerQ = *(hyperBox->getLowerBound<DiscreteQ>()); //DiscreteValue is based on std::vector<T>::const_iterator
        const float upperQ = *(hyperBox->getUpperBound<DiscreteQ>());
        const float deltaQ = 0.5 * (upperQ - lowerQ);
 
        const float centerP = *(hyperBox->getCenter<1>()); //TODO getCenter(class T) is not implemented
 
        const float centerZ0 = *(hyperBox->getCenter<2>());
 
        const double perpS = recoHit.getArcLength2D();
        const double recoZ = recoHit.getRecoZ();
 
        const bool sameSign = SameSignChecker::sameSign(catZ(lowerQ, centerP, perpS) + centerZ0 - 100.0 * Unit::cm * deltaQ - recoZ,
                                                        catZ(upperQ, centerP, perpS) + centerZ0 + 100.0 * Unit::cm * deltaQ - recoZ); //100 is a reference - size of CDC in cm
        if (not sameSign) {
          return 1.0;
        } else {
          return NAN;
        }
      }

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The documentation for this class was generated from the following file:

• tracking/trackFindingCDC/hough/algorithms/include/HitInHyperBox.h