LauKMatrixProdPole.cc

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/*
Copyright 2008 University of Warwick

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

/*
Laura++ package authors:
John Back
Paul Harrison
Thomas Latham
*/

#include "LauKMatrixProdPole.hh"
#include "LauKMatrixPropagator.hh"

#include <iostream>

ClassImp(LauKMatrixProdPole)

LauKMatrixProdPole::LauKMatrixProdPole(const TString& poleName, Int_t poleIndex, Int_t resPairAmpInt,
                                       LauKMatrixPropagator* propagator, const LauDaughters* daughters, 
                                       Bool_t useProdAdler) : 
        LauAbsResonance(poleName, resPairAmpInt, daughters),
        thePropagator_(propagator),
        poleIndex_(poleIndex - 1), // poleIndex goes from 1 to nPoles
        useProdAdler_(useProdAdler)
{

        if (useProdAdler_) {
            std::cout<<"Creating K matrix production pole "<<poleName<<" with poleIndex = "
                     <<poleIndex<<" with s-dependent production Adler zero term"<<std::endl;
        } else {
            std::cout<<"Creating K matrix production pole "<<poleName<<" with poleIndex = "
                     <<poleIndex<<" with production Adler zero factor = 1"<<std::endl;
        }

}

LauKMatrixProdPole::~LauKMatrixProdPole() 
{
}

LauComplex LauKMatrixProdPole::resAmp(Double_t mass, Double_t spinTerm)
{
        std::cerr << "ERROR in LauKMatrixProdPole::resAmp : This method shouldn't get called." << std::endl;
        std::cerr << "                                      Returning zero amplitude for mass = " << mass << " and spinTerm = " << spinTerm << "." << std::endl;
        return LauComplex(0.0, 0.0);
}

LauComplex LauKMatrixProdPole::amplitude(const LauKinematics* kinematics)
{

        // Calculate the amplitude for the K-matrix production pole.
        // First, make sure the K-matrix propagator is up-to-date for 
        // the given centre-of-mass squared value ("s") from the kinematics.
        LauComplex amp(0.0, 0.0);

        if (thePropagator_ == 0) {
                std::cerr << "ERROR in LauKMatrixProdPole::amplitude : The propagator is null" << std::endl;
                return amp;
        }

        thePropagator_->updatePropagator(kinematics);

        // Sum the pole denominator terms over all channels j, multiplying by
        // the propagator terms. Note that we do not sum over poles, since we
        // only want one of the production pole terms.
        Int_t nChannels = thePropagator_->getNChannels();
        Int_t jChannel;

        for (jChannel = 0; jChannel < nChannels; jChannel++) {

                Double_t gj = thePropagator_->getCouplingConstant(poleIndex_, jChannel);
                LauComplex prodTerm = thePropagator_->getPropTerm(jChannel);

                prodTerm.rescale(gj);

                amp += prodTerm;

        }

        Double_t poleDenom = thePropagator_->getPoleDenomTerm(poleIndex_);

        // Include Adler zero factor if requested
        Double_t adlerZero(1.0);
        if (useProdAdler_) {adlerZero = thePropagator_->getAdlerZero();}

        amp.rescale(poleDenom*adlerZero);

        return amp;

}