S_MVgamma Class Reference

A class for the \(S\) parameter for CPV in \(M \to V \gamma\) decay. More...

#include <MVgamma.h>

Inheritance diagram for S_MVgamma:

Detailed Description

A class for the \(S\) parameter for CPV in \(M \to V \gamma\) decay.

Author

HEPfit Collaboration

Copyright

GNU General Public License

This class is used to compute the \(S\) parameter of CPV in \(M \to V \gamma\) in terms of the helicity amplitudes \(H_V^{(+,-)},\overline{H}_V^{(+,-)}\), computed in the MVgamma class:

\[ S = \frac {2Im(q/p * ( H_V^{+*} \overline{H}_V^+ + H_V^{-*} \overline{H}_V^-))}{( |H_V^+|^2 + |H_V^-|^2 +|\overline{H}_V^+|^2 + |\overline{H}_V^-|^2)} \,. \]

Definition at line 786 of file MVgamma.h.

Public Member Functions
double	computeThValue ()
	The \(S\) parameter for CPV in \(M \to V \gamma\).
	S_MVgamma (const StandardModel &SM_i, QCD::meson meson_i, QCD::meson vector_i)
	Constructor.
Public Member Functions inherited from ThObservable
double	getBinMax ()
	A get method to get the maximum value of the bin.
double	getBinMin ()
	A get method to get the minimum value of the bin.
const StandardModel &	getModel ()
	A get method to get the model.
const std::vector< std::string >	getParametersForObservable ()
	A get method to get the parameters for the specific observable.
void	setBinMax (double max)
	A set method to set the maximum value of the bin.
void	setBinMin (double min)
	A set method to set the minimum value of the bin.
void	setParametersForObservable (std::vector< std::string > parametersForObservable_i)
	A set method to get the parameters for the specific observable.
	ThObservable (const StandardModel &SM_i)
	Constructor.
	ThObservable (const ThObservable &orig)
	The copy constructor.
virtual	~ThObservable ()
	The default destructor.

Private Attributes
double	arg
QCD::meson	meson
QCD::meson	vectorM

Additional Inherited Members
Protected Attributes inherited from ThObservable
double	max
	the bin maximum.
double	min
	The bin minimum.
std::vector< std::string >	parametersForObservable
	a vector of parameter namesfor the specific observable
const StandardModel &	SM
	A reference to an object of StandardMode class.

Constructor & Destructor Documentation

S_MVgamma()

S_MVgamma::S_MVgamma	(	const StandardModel &	SM_i,
		QCD::meson	meson_i,
		QCD::meson	vector_i
	)

Constructor.

Parameters

[in]	SM_i	a reference to an object of type StandardModel
[in]	meson_i	initial meson of the decay
[in]	vector_i	final vector meson of the decay

Definition at line 1012 of file MVgamma.cpp.

: ThObservable(SM_i)
{
    meson = meson_i;
    vectorM = vector_i;
    
    setParametersForObservable(SM.getFlavour().getMVgamma(meson, vectorM).initializeMVgammaParameters());
}

Member Function Documentation

computeThValue()

double S_MVgamma::computeThValue ( )

virtual

The \(S\) parameter for CPV in \(M \to V \gamma\).

Returns

\(S\)

Implements ThObservable.

Definition at line 1021 of file MVgamma.cpp.

{
    SM.getFlavour().getMVgamma(meson, vectorM).updateParameters();
    
    gslpp::complex HVm = SM.getFlavour().getMVgamma(meson, vectorM).H_V_m();
    gslpp::complex HVm_bar = SM.getFlavour().getMVgamma(meson, vectorM).H_V_m_bar();
    gslpp::complex HVp = SM.getFlavour().getMVgamma(meson, vectorM).H_V_p();
    gslpp::complex HVp_bar = SM.getFlavour().getMVgamma(meson, vectorM).H_V_p_bar();
    
    switch (vectorM) {
        case StandardModel::K_star:
        case StandardModel::RHO:
            arg = SM.getFlavour().getDB2(0).getM21(FULLNLO).arg();
            break;
        case StandardModel::PHI:
            arg = SM.getFlavour().getDB2(1).getM21(FULLNLO).arg();
            break;
        default:
            std::stringstream out;
            out << vectorM;
            throw std::runtime_error("MVgamma: vector " + out.str() + " not implemented");
    }
 
    /* For correctly defined polarization the numerator should be H_V_p().conjugate()*H_V_p_bar() + H_V_m().conjugate()*H_V_m_bar(). Switched to keep consistency with K*ll.*/
    /* See discussion around eq.53 in hep-ph/0510104*/
    return 2.*(exp(gslpp::complex::i()*arg)*(HVp.conjugate()*HVm_bar + HVm.conjugate()*HVp_bar)).imag() / (HVp.abs2() + HVm.abs2() + HVp_bar.abs2() + HVm_bar.abs2());
}

Member Data Documentation

arg

double S_MVgamma::arg

private

Definition at line 806 of file MVgamma.h.

meson

QCD::meson S_MVgamma::meson

private

Initial meson type.

Definition at line 804 of file MVgamma.h.

vectorM

QCD::meson S_MVgamma::vectorM

private

Final vector meson type.

Definition at line 805 of file MVgamma.h.

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The documentation for this class was generated from the following files:

• MVgamma.h
• MVgamma.cpp