CaloRecHitResolutionProvider.h

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#ifndef RecoParticleFlow_PFClusterProducer_CaloRecHitResolutionProvider_h
#define RecoParticleFlow_PFClusterProducer_CaloRecHitResolutionProvider_h

#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include <cmath>

class CaloRecHitResolutionProvider {
public:
  CaloRecHitResolutionProvider(const edm::ParameterSet& iConfig) {
    noiseTerm_ = iConfig.getParameter<double>("noiseTerm");
    constantTerm2_ = std::pow(iConfig.getParameter<double>("constantTerm"), 2);
    noiseTermLowE_ = iConfig.getParameter<double>("noiseTermLowE");
    corrTermLowE_ = iConfig.getParameter<double>("corrTermLowE");
    constantTermLowE2_ = std::pow(iConfig.getParameter<double>("constantTermLowE"), 2);
    threshLowE_ = iConfig.getParameter<double>("threshLowE");
    threshHighE_ = iConfig.getParameter<double>("threshHighE");

    resHighE2_ = std::pow((noiseTerm_ / threshHighE_), 2) + constantTerm2_;
  }

  double timeResolution2(double energy) {
    double res2 = 10000.;

    if (energy <= 0.)
      return res2;
    else if (energy < threshLowE_) {
      if (corrTermLowE_ > 0.) {  // different parametrisation
        const double res = noiseTermLowE_ / energy + corrTermLowE_ / (energy * energy);
        res2 = res * res;
      } else {
        const double noiseDivE = noiseTermLowE_ / energy;
        res2 = noiseDivE * noiseDivE + constantTermLowE2_;
      }
    } else if (energy < threshHighE_) {
      const double noiseDivE = noiseTerm_ / energy;
      res2 = noiseDivE * noiseDivE + constantTerm2_;
    } else  // if (energy >=threshHighE_)
      res2 = resHighE2_;

    if (res2 > 10000.)
      return 10000.;
    return res2;
  }

private:
  double noiseTerm_;      // Noise term
  double constantTerm2_;  // Constant term

  double noiseTermLowE_;      // Noise term for low E
  double constantTermLowE2_;  // Constant term for low E
  double corrTermLowE_;       // 2nd term for low E, different parametrisation

  double threshLowE_;   // different parametrisation below
  double threshHighE_;  // resolution constant above

  double resHighE2_;  // precompute res at high E
};

#endif