MeasuredBreakupMomenta.h

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/*  YAP - Yet another PWA toolkit
    Copyright 2015, Technische Universitaet Muenchen,
    Authors: Daniel Greenwald, Johannes Rauch

    This program 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.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/


#ifndef yap_MeasuredBreakupMomenta_h
#define yap_MeasuredBreakupMomenta_h

#include "fwd/CachedValue.h"
#include "fwd/Model.h"
#include "fwd/ParticleCombination.h"
#include "fwd/StatusManager.h"

#include "StaticDataAccessor.h"

#include <cmath>
#include <memory>
#include <string>

namespace yap {

class MeasuredBreakupMomenta : public StaticDataAccessor
{
public:

    MeasuredBreakupMomenta(Model& m);

    virtual void calculate(DataPoint& d, StatusManager& sm) const override;

    double q2(const DataPoint& d, const std::shared_ptr<ParticleCombination>& pc) const;

    double q(const DataPoint& d, const std::shared_ptr<ParticleCombination>& pc) const
    { return sqrt(q2(d, pc)); }

    double rho(const DataPoint& d, const std::shared_ptr<ParticleCombination>& pc) const;
    
    std::shared_ptr<RealCachedValue> breakupMomenta()
    { return Q2_; }

    std::shared_ptr<RealCachedValue> breakupMomenta() const
    { return Q2_; }

    friend class Model;

    friend class DataAccessor;

protected:

    void virtual addToStaticDataAccessors() override;

    void addParticleCombination(std::shared_ptr<ParticleCombination> pc) override;

    std::shared_ptr<RealCachedValue> Q2_;

};

inline constexpr double squared_breakup_momentum(double m2_R, double m_a, double m_b)
{
    return (m_a == m_b)
        ?
        m2_R / 4. - m_a * m_a
        :
        (m2_R - pow(m_a + m_b, 2)) * (m2_R - pow(m_a - m_b, 2)) / m2_R / 4.;
}


}

#endif