AlphaT Class Reference

#include <AlphaT.h>

Public Member Functions
template<class T >
	AlphaT (std::vector< T const * > const &p4, bool use_et=true)
template<class T >
	AlphaT (std::vector< T > const &p4, bool use_et=true)
double	value (void) const
double	value (std::vector< bool > &jet_sign) const

Private Member Functions
double	value_ (std::vector< bool > *jet_sign) const

Private Attributes
std::vector< double >	et_
std::vector< double >	px_
std::vector< double >	py_

Detailed Description

Definition at line 9 of file AlphaT.h.

Constructor & Destructor Documentation

template<class T >

AlphaT::AlphaT	(	std::vector< T const * > const &	p4,
		bool	use_et = true
	)

Definition at line 33 of file AlphaT.h.

References et_, reco::tau::disc::Pt(), px_, py_, and create_public_lumi_plots::transform.

                                                             {
  std::transform( p4.begin(), p4.end(), back_inserter(et_), ( use_et ? std::mem_fun(&T::Et) : std::mem_fun(&T::Pt) ) );
  std::transform( p4.begin(), p4.end(), back_inserter(px_), std::mem_fun(&T::Px) );
  std::transform( p4.begin(), p4.end(), back_inserter(py_), std::mem_fun(&T::Py) );
}

template<class T >

AlphaT::AlphaT	(	std::vector< T > const &	p4,
		bool	use_et = true
	)

Definition at line 41 of file AlphaT.h.

References et_, reco::tau::disc::Pt(), px_, py_, and create_public_lumi_plots::transform.

                                                     {
  std::transform( p4.begin(), p4.end(), back_inserter(et_), std::mem_fun_ref( use_et ? &T::Et : &T::Pt ) );
  std::transform( p4.begin(), p4.end(), back_inserter(px_), std::mem_fun_ref(&T::Px) );
  std::transform( p4.begin(), p4.end(), back_inserter(py_), std::mem_fun_ref(&T::Py) );
}

Member Function Documentation

double AlphaT::value ( void  ) const

inline

Definition at line 50 of file AlphaT.h.

References value_().

Referenced by HLTAlphaTFilter< T >::hltFilter().

                               {
  return value_(0);
}

double AlphaT::value ( std::vector< bool > &  jet_sign ) const

inline

Definition at line 56 of file AlphaT.h.

References value_().

                                                     {
  return value_(& jet_sign);
}

double AlphaT::value_ ( std::vector< bool > *  jet_sign ) const

private

Definition at line 3 of file AlphaT.cc.

References funct::abs(), et_, i, j, max(), px_, py_, and mathSSE::sqrt().

Referenced by value().

                                                      {

  // Clear pseudo-jet container
  if (jet_sign) {
    jet_sign->clear();
    jet_sign->resize(et_.size());
  }

  // check the size of the input collection
  if (et_.size() == 0)
    // empty jet collection, return AlphaT = 0
    return 0.;

  if (et_.size() > (unsigned int) std::numeric_limits<unsigned int>::digits)
    // too many jets, return AlphaT = a very large number
    return std::numeric_limits<double>::max();

  // Momentum sums in transverse plane
  const double sum_et = std::accumulate( et_.begin(), et_.end(), 0. );
  const double sum_px = std::accumulate( px_.begin(), px_.end(), 0. );
  const double sum_py = std::accumulate( py_.begin(), py_.end(), 0. );

  // Minimum Delta Et for two pseudo-jets
  double min_delta_sum_et = sum_et;

  for (unsigned int i = 0; i < (1U << (et_.size() - 1)); i++) { //@@ iterate through different combinations
    double delta_sum_et = 0.;
    for (unsigned int j = 0; j < et_.size(); ++j) { //@@ iterate through jets
      if (i & (1U << j))
        delta_sum_et -= et_[j];
      else
        delta_sum_et += et_[j];
    }
    delta_sum_et = std::abs(delta_sum_et);
    if (delta_sum_et < min_delta_sum_et) {
      min_delta_sum_et = delta_sum_et;
      if (jet_sign) {
        for (unsigned int j = 0; j < et_.size(); ++j)
          (*jet_sign)[j] = ((i & (1U << j)) == 0);
      }
    }
  }

  // Alpha_T
  return (0.5 * (sum_et - min_delta_sum_et) / sqrt( sum_et*sum_et - (sum_px*sum_px+sum_py*sum_py) ));  
}

Member Data Documentation

std::vector<double> AlphaT::et_

private

Definition at line 18 of file AlphaT.h.

Referenced by AlphaT(), and value_().

std::vector<double> AlphaT::px_

private

Definition at line 19 of file AlphaT.h.

Referenced by AlphaT(), and value_().

std::vector<double> AlphaT::py_

private

Definition at line 20 of file AlphaT.h.

Referenced by AlphaT(), and value_().