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 21 of file FTSFromVertexToPointFactory.cc.

References f, dqmMemoryStats::float, runTauDisplay::gp, MagneticField::inTesla(), eostools::move(), PV3DBase< T, PVType, FrameType >::perp(), DiDispStaMuonMonitor_cfi::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(), TrackingRegionsFromSuperClustersProducer::createTrackingRegion(), betterConfigParser.BetterConfigParser::getCompares(), betterConfigParser.BetterConfigParser::getGeneral(), TrajSeedMatcher::getNrValidLayersAlongTraj(), betterConfigParser.BetterConfigParser::getResultingSection(), TrajSeedMatcher::makeTrajStateOnSurface(), PixelHitMatcher::operator()(), TrajSeedMatcher::processSeed(), and SeedFilter::seeds().

                                                                         {
  auto magFieldAtPoint = magField.inTesla(xmeas);
  auto BInTesla = magFieldAtPoint.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, std::move(magFieldAtPoint));

  return FreeTrajectoryState(gp);
}