Page MenuHomeHEPForge
Files F19250512

EvtEta2MuMuGamma.cpp
No OneTemporary
Actions

Size
3 KB
Referenced Files
None
Subscribers
None

EvtEta2MuMuGamma.cpp
View Options

/***********************************************************************
* Copyright 1998-2020 CERN for the benefit of the EvtGen authors *
* *
* This file is part of EvtGen. *
* *
* EvtGen is free software: you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* EvtGen is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with EvtGen. If not, see <https://www.gnu.org/licenses/>. *
***********************************************************************/
#include "EvtGenModels/EvtEta2MuMuGamma.hh"
#include "EvtGenBase/EvtDiracSpinor.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtTensor4C.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include <fstream>
#include <stdio.h>
#include <stdlib.h>
#include <string>
using std::fstream;
std::string EvtEta2MuMuGamma::getName()
{
return "ETA2MUMUGAMMA";
}
EvtDecayBase* EvtEta2MuMuGamma::clone()
{
return new EvtEta2MuMuGamma;
}
void EvtEta2MuMuGamma::initProbMax()
{
setProbMax( 3.5 );
}
void EvtEta2MuMuGamma::init()
{
// check that there are 0 arguments
checkNArg( 0 );
checkNDaug( 3 );
checkSpinParent( EvtSpinType::SCALAR );
checkSpinDaughter( 0, EvtSpinType::DIRAC );
checkSpinDaughter( 1, EvtSpinType::DIRAC );
checkSpinDaughter( 2, EvtSpinType::PHOTON );
}
void EvtEta2MuMuGamma::decay( EvtParticle* p )
{
EvtParticle *ep, *em, *gamma;
setWeight( p->initializePhaseSpace( getNDaug(), getDaugs(), false,
0.00000002, 0, 1 ) );
ep = p->getDaug( 0 );
em = p->getDaug( 1 );
gamma = p->getDaug( 2 );
// the next four lines generates events with a weight such that
// the efficiency for selecting them is good. The parameter below of
// 0.1 is the size of the peak at low q^2 (in arbitrary units).
// The value of 0.1 is appropriate for muons.
// when you use this remember to remove the cut on q^2!
//ep em invariant mass^2
double m2 = ( ep->getP4() + em->getP4() ).mass2();
EvtVector4R q = ep->getP4() + em->getP4();
//Just use the prob summed over spins...
EvtTensor4C w, v;
v = 2.0 * ( gamma->getP4() * q ) *
EvtGenFunctions::directProd( q, gamma->getP4() ) -
( gamma->getP4() * q ) * ( gamma->getP4() * q ) * EvtTensor4C::g() -
m2 * EvtGenFunctions::directProd( gamma->getP4(), gamma->getP4() );
w = 4.0 * ( EvtGenFunctions::directProd( ep->getP4(), em->getP4() ) +
EvtGenFunctions::directProd( em->getP4(), ep->getP4() ) -
EvtTensor4C::g() *
( ep->getP4() * em->getP4() - ep->getP4().mass2() ) );
double prob = ( real( cont( v, w ) ) ) / ( m2 * m2 );
prob *= ( 1.0 / ( ( 0.768 * 0.768 - m2 ) * ( 0.768 * 0.768 - m2 ) +
0.768 * 0.768 * 0.151 * 0.151 ) );
// EvtGenReport(EVTGEN_INFO,"EvtGen") << "prob is "<<prob<<endl;
setProb( prob );
return;
}

File Metadata

Mime Type
text/x-c
Expires
Tue, Sep 30, 5:41 AM (1 h, 7 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
6562853
Default Alt Text
EvtEta2MuMuGamma.cpp (3 KB)

Event Timeline

HEPForge.org · .