EvtTwoBodyKine.cc

Go to the documentation of this file.

#include "EvtPatches.hh"
/*******************************************************************************
 * Project: BaBar detector at the SLAC PEP-II B-factory
 * Package: EvtGenBase
 *    File: $Id: EvtTwoBodyKine.cc,v 1.1.1.2 2007/10/26 05:03:14 pingrg Exp $
 *  Author: Alexei Dvoretskii, dvoretsk@slac.stanford.edu, 2001-2002
 *
 * Copyright (C) 2002 Caltech
 *******************************************************************************/
 
#include "EvtReport.hh"
#include "EvtTwoBodyKine.hh"
#include <assert.h>
#include <iostream>
#include <math.h>
using std::endl;
using std::ostream;
 
EvtTwoBodyKine::EvtTwoBodyKine() : _mA( 0. ), _mB( 0. ), _mAB( 0. ) {}
 
EvtTwoBodyKine::EvtTwoBodyKine( double mA, double mB, double mAB )
    : _mA( mA ), _mB( mB ), _mAB( mAB ) {
  if ( mAB < mA + mB )
  {
 
    report( INFO, "EvtGen" ) << mAB << " < " << mA << " + " << mB << endl;
    assert( 0 );
  }
}
 
EvtTwoBodyKine::EvtTwoBodyKine( const EvtTwoBodyKine& other )
    : _mA( other._mA ), _mB( other._mB ), _mAB( other._mAB ) {}
 
EvtTwoBodyKine::~EvtTwoBodyKine() {}
 
double EvtTwoBodyKine::m( Index i ) const {
  double ret = _mAB;
  if ( A == i ) ret = _mA;
  else if ( B == i ) ret = _mB;
 
  return ret;
}
 
double EvtTwoBodyKine::p( Index i ) const {
  double p0 = 0.;
 
  if ( i == AB )
  {
 
    double x = _mAB * _mAB - _mA * _mA - _mB * _mB;
    double y = 2 * _mA * _mB;
    p0       = sqrt( x * x - y * y ) / 2. / _mAB;
  }
  else if ( i == A )
  {
 
    double x = _mA * _mA - _mAB * _mAB - _mB * _mB;
    double y = 2 * _mAB * _mB;
    p0       = sqrt( x * x - y * y ) / 2. / _mA;
  }
  else
  {
 
    double x = _mB * _mB - _mAB * _mAB - _mA * _mA;
    double y = 2 * _mAB * _mA;
    p0       = sqrt( x * x - y * y ) / 2. / _mB;
  }
 
  return p0;
}
 
double EvtTwoBodyKine::e( Index i, Index j ) const {
  double ret = m( i );
  if ( i != j )
  {
 
    double pD = p( j );
    ret       = sqrt( ret * ret + pD * pD );
  }
  return ret;
}
 
void EvtTwoBodyKine::print( ostream& os ) const {
  os << " mA = " << _mA << endl;
  os << " mB = " << _mB << endl;
  os << "mAB = " << _mAB << endl;
}
 
ostream& operator<<( ostream& os, const EvtTwoBodyKine& p ) {
  p.print( os );
  return os;
}