FTSFromVertexToPointFactory Class Reference

#include <FTSFromVertexToPointFactory.h>

Static Public Member Functions
static FreeTrajectoryState	get (MagneticField const &magField, GlobalPoint const &xmeas, GlobalPoint const &xvert, float momentum, TrackCharge charge)

Detailed Description

Description: Utility class to create FTS from supercluster

Implementation: should go somewhere else in the future

Definition at line 29 of file FTSFromVertexToPointFactory.h.

Member Function Documentation

FreeTrajectoryState FTSFromVertexToPointFactory::get ( MagneticField const &  magField, GlobalPoint const &  xmeas, GlobalPoint const &  xvert, float  momentum, TrackCharge  charge  )

static

Definition at line 22 of file FTSFromVertexToPointFactory.cc.

References f, MagneticField::inTesla(), PV3DBase< T, PVType, FrameType >::perp(), EnergyCorrector::pt, mathSSE::sqrt(), Vector3DBase< T, FrameTag >::unit(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by Options.Options::__getitem__(), betterConfigParser.BetterConfigParser::__updateDict(), ElectronSeedAnalyzer::analyze(), HLTPMMassFilter::approxMomAtVtx(), PixelHitMatcher::compatibleHits(), PixelHitMatcher::compatibleSeeds(), betterConfigParser.BetterConfigParser::getCompares(), betterConfigParser.BetterConfigParser::getGeneral(), betterConfigParser.BetterConfigParser::getResultingSection(), and SeedFilter::seeds().

{
  auto BInTesla = magField.inTesla(xmeas).z();
  GlobalVector xdiff = xmeas - xvert;
  auto mom = momentum*xdiff.unit();
  auto pt = mom.perp();
  auto pz = mom.z();
  auto pxOld = mom.x();
  auto pyOld = mom.y();


  auto curv = (BInTesla*0.29979f*0.01f)/pt;

  // stays as doc...
  // auto alpha = std::asin(0.5f*xdiff.perp()*curv);
  // auto ca = std::cos(float(charge)*alpha);
  // auto sa = std::sin(float(charge)*alpha);
 
  auto sa = 0.5f*xdiff.perp()*curv*float(charge);
  auto ca = sqrt(1.f-sa*sa); 

  auto pxNew =   ca*pxOld + sa*pyOld;
  auto pyNew =  -sa*pxOld + ca*pyOld;
  GlobalVector pNew(pxNew, pyNew, pz);  

  GlobalTrajectoryParameters gp(xmeas, pNew, charge, & magField);
  
  return FreeTrajectoryState(gp);
}