LauLASSNRRes.cc

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// Copyright University of Warwick 2008 - 2014.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

// Authors:
// Thomas Latham
// John Back
// Paul Harrison

#include <iostream>

#include "LauConstants.hh"
#include "LauLASSNRRes.hh"
#include "LauResonanceInfo.hh"

ClassImp(LauLASSNRRes)


LauLASSNRRes::LauLASSNRRes(LauResonanceInfo* resInfo, const Int_t resPairAmpInt, const LauDaughters* daughters) :
        LauAbsResonance(resInfo, resPairAmpInt, daughters),
        r_(0),
        a_(0),
        cutOff_(0.0)
{
        // Default values for LASS parameters
        cutOff_ = 1.8;
        const Double_t rVal = 3.32;
        const Double_t aVal = 2.07;

        const TString& parNameBase = this->getSanitisedName();

        TString rName(parNameBase);
        rName += "_r";
        r_ = resInfo->getExtraParameter( rName );
        if ( r_ == 0 ) {
                r_ = new LauParameter( rName, rVal, 0.0, 10.0, kTRUE );
                r_->secondStage(kTRUE);
                resInfo->addExtraParameter( r_ );
        }

        TString aName(parNameBase);
        aName += "_a";
        a_ = resInfo->getExtraParameter( aName );
        if ( a_ == 0 ) {
                a_ = new LauParameter( aName, aVal, 0.0, 10.0, kTRUE );
                a_->secondStage(kTRUE);
                resInfo->addExtraParameter( a_ );
        }
}

LauLASSNRRes::~LauLASSNRRes()
{
}

void LauLASSNRRes::initialise()
{
        Int_t resSpin = this->getSpin();
        if (resSpin != 0) {
                std::cerr << "WARNING in LauLASSNRRes::amplitude : Resonance spin is " << resSpin << "." << std::endl;
                std::cerr << "                                   : LASS amplitude is only for scalers, resetting spin to 0." << std::endl;
                this->changeResonance( -1.0, -1.0, 0 );
        }
}

LauComplex LauLASSNRRes::resAmp(Double_t mass, Double_t /*spinTerm*/)
{
        LauComplex bkgAmplitude(0.0, 0.0);

        if (mass < 1e-10) {
                std::cerr << "WARNING in LauLASSNRRes::amplitude : mass < 1e-10." << std::endl;
                return LauComplex(0.0, 0.0);
        }

        if (mass < cutOff_) {
                // q is the momentum of either daughter in the resonance rest-frame
                const Double_t q = this->getQ();

                // Calculate the phase shift term
                const Double_t rVal = this->getEffectiveRange();
                const Double_t aVal = this->getScatteringLength();
                const Double_t qcotdeltaB = 1.0/aVal + (rVal*q*q)/2.0;

                // Compute the complex amplitude
                bkgAmplitude = LauComplex(qcotdeltaB, q);

                // Scale by the numerator and denominator factors
                bkgAmplitude.rescale(mass/(qcotdeltaB*qcotdeltaB + q*q));
        }

        return bkgAmplitude;

}

const std::vector<LauParameter*>& LauLASSNRRes::getFloatingParameters()
{
        this->clearFloatingParameters();

        if ( ! this->fixMass() ) {
                this->addFloatingParameter( this->getMassPar() );
        }

        if ( ! this->fixWidth() ) {
                this->addFloatingParameter( this->getWidthPar() );
        }

        if ( ! this->fixEffectiveRange() ) {
                this->addFloatingParameter( r_ );
        }

        if ( ! this->fixScatteringLength() ) {
                this->addFloatingParameter( a_ );
        }

        return this->getParameters();
}

void LauLASSNRRes::setResonanceParameter(const TString& name, const Double_t value)
{
        // Set various parameters for the LASS lineshape dynamics
        if (name == "a") {
                this->setScatteringLength(value);
                std::cout << "INFO in LauLASSNRRes::setResonanceParameter : Setting LASS Scattering Length = " << this->getScatteringLength() << std::endl;
        } else if (name == "r") {
                this->setEffectiveRange(value);
                std::cout << "INFO in LauLASSNRRes::setResonanceParameter : Setting LASS Effective Range = " << this->getEffectiveRange() << std::endl;
        } else {
                std::cerr << "WARNING in LauLASSNRRes::setResonanceParameter: Parameter name not reconised.  No parameter changes made." << std::endl;
        }
}

void LauLASSNRRes::floatResonanceParameter(const TString& name)
{
        if (name == "a") {
                if ( a_->fixed() ) {
                        a_->fixed( kFALSE );
                        this->addFloatingParameter( a_ );
                } else {
                        std::cerr << "WARNING in LauLASSNRRes::floatResonanceParameter: Parameter already floating.  No parameter changes made." << std::endl;
                }
        } else if (name == "r") {
                if ( r_->fixed() ) {
                        r_->fixed( kFALSE );
                        this->addFloatingParameter( r_ );
                } else {
                        std::cerr << "WARNING in LauLASSNRRes::floatResonanceParameter: Parameter already floating.  No parameter changes made." << std::endl;
                }
        } else {
                std::cerr << "WARNING in LauLASSNRRes::fixResonanceParameter: Parameter name not reconised.  No parameter changes made." << std::endl;
        }
}

LauParameter* LauLASSNRRes::getResonanceParameter(const TString& name)
{
        if (name == "a") {
                return a_;
        } else if (name == "r") {
                return r_;
        } else {
                std::cerr << "WARNING in LauLASSNRRes::getResonanceParameter: Parameter name not reconised." << std::endl;
                return 0;
        }
}

void LauLASSNRRes::setEffectiveRange(const Double_t r)
{
        r_->value( r );
        r_->genValue( r );
        r_->initValue( r );
}

void LauLASSNRRes::setScatteringLength(const Double_t a)
{
        a_->value( a );
        a_->genValue( a );
        a_->initValue( a );
}