DVCS/cross_section/DVCSCrossSectionDifferenceLUMinus.h

0001 #ifndef DVCSCROSSSECTIONDIFFERENCELUMINUS_H
0002 #define DVCSCROSSSECTIONDIFFERENCELUMINUS_H
0003
0004 /**
0005  * @file DVCSCrossSectionDifferenceLUMinus.h
0006  * @author Pawel Sznajder (IPNO)
0007  * @date November 25, 2016
0008  * @version 1.0
0009  */
0010
0011 #include <string>
0012
0013 #include "../../../../beans/gpd/GPDType.h"
0014 #include "../../../../beans/List.h"
0015 #include "../../../../utils/type/PhysicalType.h"
0016 #include "../DVCSObservable.h"
0017
0018 namespace PARTONS {
0019
0020 /**
0021  * @class DVCSCrossSectionDifferenceLUMinus
0022  * @brief Unpolarized cross-section difference for longitudinally polarized beam and negative beam charge.
0023  *
0024  * Definition:<br>
0025  *
0026  * \f$ \displaystyle
0027  * \frac{\Delta \mathrm{d}^4\sigma_{LU}}
0028  * {\mathrm{d}x_{B} \mathrm{d}|t| \mathrm{d}Q^2 \mathrm{d}\phi}\left(x_{B}, t, Q^2, \phi\right) =
0029  * \frac{1}{2} \left(
0030  * \frac{\mathrm{d}^4\sigma^{\rightarrow -}}{\mathrm{d}x_{B} \mathrm{d}|t| \mathrm{d}Q^2 \mathrm{d}\phi}\left(x_{B}, t, Q^2, \phi\right) -
0031  * \frac{\mathrm{d}^4\sigma^{\leftarrow -}}{\mathrm{d}x_{B} \mathrm{d}|t| \mathrm{d}Q^2 \mathrm{d}\phi}\left(x_{B}, t, Q^2, \phi\right)
0032  * \right) \, ,
0033  * \f$
0034  *
0035  * where
0036  * \f$\sigma^{b_{h} b_{c}}\f$ is a single photon production cross-section (DVCS, BH and Interference) for beam helicity denoted by \f$b_{h}\f$ and beam charge denoted by \f$b_{c}\f$.
0037  *
0038  * Unit: \f$\mathrm{nbarn}/\mathrm{GeV}^4\f$.
0039  */
0040 class DVCSCrossSectionDifferenceLUMinus: public DVCSObservable {
0041
0042 public:
0043
0044     /**
0045      * Unique ID to automatically register the class in the registry.
0046      */
0047     static const unsigned int classId;
0048
0049     /**
0050      * Constructor.
0051      * @param className Name of class.
0052      */
0053     DVCSCrossSectionDifferenceLUMinus(const std::string &className);
0054
0055     /**
0056      * Destructor.
0057      */
0058     virtual ~DVCSCrossSectionDifferenceLUMinus();
0059
0060     virtual DVCSCrossSectionDifferenceLUMinus* clone() const;
0061
0062 protected:
0063
0064     /**
0065      * Copy constructor.
0066      * @param other Object to be copied.
0067      */
0068     DVCSCrossSectionDifferenceLUMinus(
0069             const DVCSCrossSectionDifferenceLUMinus &other);
0070
0071     virtual PhysicalType<double> computeObservable(
0072             const DVCSObservableKinematic& kinematic,
0073             const List<GPDType>& gpdType);
0074 };
0075
0076 } /* namespace PARTONS */
0077
0078 #endif /* DVCSCROSSSECTIONDIFFERENCELUMINUS_H */