BR_MVgamma Class Reference

A class for the \(BR\) in \(M \to V \gamma\) decay. More...

#include <MVgamma.h>

Inheritance diagram for BR_MVgamma:

Detailed Description

A class for the \(BR\) in \(M \to V \gamma\) decay.

Author

HEPfit Collaboration

Copyright

GNU General Public License

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

\[ BR = \frac {\alpha_e G_F^2 M_b^2 M_M \lambda}{(4\pi)^2 4 w_M} ( |H_V^+|^2 + |H_A^+|^2 +|\overline{H}_V^-|^2 + |\overline{H}_A^-|^2) \,. \]

Definition at line 534 of file MVgamma.h.

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

Private Attributes
double	ADG
double	arg
QCD::meson	meson
double	t_int
QCD::meson	vectorM
double	ys

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

Constructor & Destructor Documentation

BR_MVgamma()

BR_MVgamma::BR_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 798 of file MVgamma.cpp.

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

Member Function Documentation

computeBR_MVgamma()

double BR_MVgamma::computeBR_MVgamma	(	QCD::meson	meson,
		QCD::meson	vector
	)

The \(BR\) in \(M \to V \gamma\).

Returns

\(BR\)

Definition at line 807 of file MVgamma.cpp.

{
    QCD::meson meson_i = meson;
    QCD::meson vector_i = vector;
    
    SM.getFlavour().getMVgamma(meson_i, vector_i).updateParameters();
    
    gslpp::complex HVm = SM.getFlavour().getMVgamma(meson_i, vector_i).H_V_m();
    gslpp::complex HVm_bar = SM.getFlavour().getMVgamma(meson_i, vector_i).H_V_m_bar();
    gslpp::complex HVp = SM.getFlavour().getMVgamma(meson_i, vector_i).H_V_p();
    gslpp::complex HVp_bar = SM.getFlavour().getMVgamma(meson_i, vector_i).H_V_p_bar();
    
    switch (vector_i) {
        case StandardModel::K_star:
        case StandardModel::K_star_P:
        case StandardModel::RHO:
        case StandardModel::RHO_P:
        case StandardModel::OMEGA:
            arg = SM.getFlavour().getDB2(0).getM21(FULLNLO).arg();
            t_int = 1.;
            break;
        case StandardModel::PHI:
            arg = SM.getFlavour().getDB2(1).getM21(FULLNLO).arg();
            /* 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*/
            ADG = 2.*(exp(gslpp::complex::i()*arg)*(HVp.conjugate()*HVm_bar + HVm.conjugate()*HVp_bar)).real() / (HVp.abs2() + HVm.abs2() + HVp_bar.abs2() + HVm_bar.abs2());
            ys = SM.getMesons(QCD::B_S).getDgamma_gamma()/2.;
            t_int = (1. - ADG * ys)/(1. - ys*ys);
            break;
        default:
            std::stringstream out;
            out << vector_i;
            throw std::runtime_error("MVgamma: vector " + out.str() + " not implemented");
    }
    
    double GF = SM.getGF();
    double ale = SM.getAle();
    double MM = SM.getMesons(meson_i).getMass();
    double MM2 = MM * MM;
    double Mb = SM.getQuarks(QCD::BOTTOM).getMass();
    double MV = SM.getMesons(vector_i).getMass();
    double width = SM.getMesons(meson_i).computeWidth();
    double lambda = MM2 - pow(MV, 2.);
    
    
    return ale * pow(GF * Mb / (4 * M_PI * M_PI), 2.) * MM * lambda / (4. * width) * (HVp.abs2() + HVm.abs2() + HVp_bar.abs2() + HVm_bar.abs2()) * t_int;
}

computeThValue()

double BR_MVgamma::computeThValue ( )

virtual

Implements ThObservable.

Reimplemented in R_MVgamma, and D0p_MVgamma.

Definition at line 855 of file MVgamma.cpp.

{
    return computeBR_MVgamma(meson, vectorM);
}

Member Data Documentation

ADG

double BR_MVgamma::ADG

private

\(A_{\Delta\Gamma}\)

Definition at line 557 of file MVgamma.h.

arg

double BR_MVgamma::arg

private

Definition at line 556 of file MVgamma.h.

meson

QCD::meson BR_MVgamma::meson

private

Initial meson type.

Definition at line 554 of file MVgamma.h.

t_int

double BR_MVgamma::t_int

private

\(\frac{\Delta\Gamma}{\Gamma}\)

Definition at line 559 of file MVgamma.h.

vectorM

QCD::meson BR_MVgamma::vectorM

private

Final vector meson type.

Definition at line 555 of file MVgamma.h.

ys

double BR_MVgamma::ys

private

Definition at line 558 of file MVgamma.h.

---

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

• MVgamma.h
• MVgamma.cpp