The class provides the form factors for semileptonic D and D* decays with full mass dependence. More...

#include <EvtBGLFF.h>

Inheritance diagram for EvtBGLFF:

Public Member Functions
	EvtBGLFF (double bglap_0, double bglap_1, double bglap_2, double bglap_3, double bgla0_0, double bgla0_1, double bgla0_2, double bgla0_3)
	Default constructor.

	EvtBGLFF (double bgla_0, double bgla_1, double bglb_0, double bglb_1, double bglc_1, double bglc_2)
	Default constructor.

void	getscalarff (EvtId parent, EvtId daught, double t, double mass, double fp, double f0)
	Returns scalar ffs.

void	getvectorff (EvtId parent, EvtId daught, double t, double mass, double a1f, double a2f, double vf, double a0f)
	Returns vector ffs.

void	gettensorff (EvtId, EvtId, double, double, double , double , double , double )
	Returns tensor ffs.

void	getbaryonff (EvtId, EvtId, double, double, double , double , double , double )
	Returns baryon ffs.

void	getdiracff (EvtId, EvtId, double, double, double , double , double , double , double , double )
	Returns dirac ffs.

void	getraritaff (EvtId, EvtId, double, double, double , double , double , double , double , double , double , double )
	Returns tarita ffs.

Private Attributes
double	ap_0 {0}
	B -> Dlnu: ai_n (i = p —vector, 0 —scalar; n = 0,1,2,3) are free coefficients of z expansion in dispersion relation parametrization from C.G.Boyd, B.Grinstein, R.F.Lebed, Phys.

double	ap_1 {0}
	1st-order z expansion coeffieient for vector form factor: f_+

double	ap_2 {0}
	2nd-order z expansion coeffieient for vector form factor: f_+

double	ap_3 {0}
	3rd-order z expansion coeffieient for vector form factor: f_+

double	a0_0 {0}
	0th-order z expansion coeffieient for scalar form factor f_0

double	a0_1 {0}
	1st-order z expansion coeffieient for scalar form factor f_0

double	a0_2 {0}
	2nd-order z expansion coeffieient for scalar form factor f_0

double	a0_3 {0}
	3rd-order z expansion coeffieient for scalar form factor f_0

double	a_0 {0}
	B->D*lnu z expansion coeffieients

double	a_1 {0}
	1st-order z expansion coeffieient for form factor g

double	b_0 {0}
	0th-order z expansion coeffieient for form factor f

double	b_1 {0}
	1st-order z expansion coeffieient for form factor f

double	c_1 {0}
	1st-order z expansion coeffieient for form factor F1

double	c_2 {0}
	2nd-order z expansion coeffieient for form factor F1

Detailed Description

The class provides the form factors for semileptonic D and D* decays with full mass dependence.

Definition at line 17 of file EvtBGLFF.h.

Constructor & Destructor Documentation

◆ EvtBGLFF() [1/2]

EvtBGLFF	(	double	bglap_0,
		double	bglap_1,
		double	bglap_2,
		double	bglap_3,
		double	bgla0_0,
		double	bgla0_1,
		double	bgla0_2,
		double	bgla0_3
	)

Default constructor.

Definition at line 18 of file EvtBGLFF.cc.

{
 
  ap_0 = bglap_0;
  ap_1 = bglap_1;
  ap_2 = bglap_2;
  ap_3 = bglap_3;
 
  a0_0 = bgla0_0;
  a0_1 = bgla0_1;
  a0_2 = bgla0_2;
  a0_3 = bgla0_3;
 
  return;
}

◆ EvtBGLFF() [2/2]

EvtBGLFF	(	double	bgla_0,
		double	bgla_1,
		double	bglb_0,
		double	bglb_1,
		double	bglc_1,
		double	bglc_2
	)

Default constructor.

Definition at line 37 of file EvtBGLFF.cc.

{
 
  a_0 = bgla_0;
  a_1 = bgla_1;
 
  b_0 = bglb_0;
  b_1 = bglb_1;
 
  c_1 = bglc_1;
  c_2 = bglc_2;
 
  return;
}

Member Function Documentation

◆ getbaryonff()

void getbaryonff	(	EvtId	,
		EvtId	,
		double	,
		double	,
		double *	,
		double *	,
		double *	,
		double *
	)

Returns baryon ffs.

Definition at line 164 of file EvtBGLFF.cc.

{
 
  EvtGenReport(EVTGEN_ERROR, "EvtGen") << "Not implemented :getbaryonff in EvtBGLFF.\n";
  ::abort();
 
}

◆ getdiracff()

void getdiracff	(	EvtId	,
		EvtId	,
		double	,
		double	,
		double *	,
		double *	,
		double *	,
		double *	,
		double *	,
		double *
	)

Returns dirac ffs.

Definition at line 173 of file EvtBGLFF.cc.

{
 
  EvtGenReport(EVTGEN_ERROR, "EvtGen") << "Not implemented :getdiracff in EvtBGLFF.\n";
  ::abort();
 
}

◆ getraritaff()

void getraritaff	(	EvtId	,
		EvtId	,
		double	,
		double	,
		double *	,
		double *	,
		double *	,
		double *	,
		double *	,
		double *	,
		double *	,
		double *
	)

Returns tarita ffs.

Definition at line 182 of file EvtBGLFF.cc.

{
 
  EvtGenReport(EVTGEN_ERROR, "EvtGen") << "Not implemented :getraritaff in EvtBGLFF.\n";
  ::abort();
 
}

◆ getscalarff()

void getscalarff	(	EvtId	parent,
		EvtId	daught,
		double	t,
		double	mass,
		double *	fp,
		double *	f0
	)

Returns scalar ffs.

Definition at line 66 of file EvtBGLFF.cc.

{
 
  double mb = EvtPDL::getMeanMass(parent);
  double r = mass / mb;
  double w = ((mb * mb) + (mass * mass) - t) / (2.0 * mb * mass);
  const double z = (sqrt(w + 1) - sqrt(2.)) / (sqrt(w + 1) + sqrt(2.));
  const double p_i = 1.0;
 
  double phi_sub = (1 + r) * (1 - z) + 2.0 * sqrt(r) * (1 + z);
 
  double phi_p = 1.1213 * pow(1 + z, 2.) * sqrt(1 - z) * pow(phi_sub, -5);
 
  double phi_0 = 0.5299 * (1 + z) * pow(1 - z, 1.5) * pow(phi_sub, -4);
 
 
  *fp = (ap_0 + ap_1 * z + ap_2 * z * z + ap_3 * z * z * z) / (p_i * phi_p);
 
  *f0 = (a0_0 + a0_1 * z + a0_2 * z * z + a0_3 * z * z * z) / (p_i * phi_0);
 
  return;
}

◆ gettensorff()

void gettensorff	(	EvtId	,
		EvtId	,
		double	,
		double	,
		double *	,
		double *	,
		double *	,
		double *
	)

Returns tensor ffs.

Definition at line 153 of file EvtBGLFF.cc.

{
 
  EvtGenReport(EVTGEN_ERROR, "EvtGen") << "Not implemented :gettensorff in EvtBGLFF.\n";
  ::abort();
 
}

◆ getvectorff()

void getvectorff	(	EvtId	parent,
		EvtId	daught,
		double	t,
		double	mass,
		double *	a1f,
		double *	a2f,
		double *	vf,
		double *	a0f
	)

Returns vector ffs.

Definition at line 95 of file EvtBGLFF.cc.

{
 
  double mb = EvtPDL::getMeanMass(parent);
  double w = ((mb * mb) + (mass * mass) - t) / (2. * mb * mass);
 
  // Form factors have a general form, with parameters passed in
  // from the arguements.
 
  const double r = mass / mb;
  double z = (sqrt(w + 1.) - sqrt(2.)) / (sqrt(w + 1) + sqrt(2.));
  const double rstar = (2. * sqrt(mb * mass)) / (mb + mass);
  const double chiT_plus33 = 5.28e-4;
  const double chiT_minus33 = 3.07e-4;
  const double n_i = 2.6;
  const double axialvector_poles[4] = {6.730, 6.736, 7.135, 7.142};
  const double vector_poles[4] = {6.337, 6.899, 7.012, 7.280};
 
  const double c_0 = (mb - mass) / mb * sqrt(0.5) / (1 + r + 2. * sqrt(r)) * b_0;
 
  double phi_g = sqrt(256. * n_i / (3. * M_PI * chiT_plus33)) * r * r * (1. + z) * (1. + z) / sqrt(1. - z) / pow((1. + r) *
                 (1. - z) + 2. * sqrt(r) * (1. + z), 4.);
  double phi_f = 1. / (mb * mb) * sqrt(16. * n_i / (3. * M_PI * chiT_minus33)) * r * (1. + z) * pow(1. - z,
                 1.5) / pow((1. + r) * (1. - z) + 2. * sqrt(r) * (1. + z), 4.);
  double phi_F1 = 1. / (mb * mb * mb) * sqrt(8. * n_i / (3. * M_PI * chiT_minus33)) * r * (1. + z) * pow(1. - z,
                  2.5) / pow((1. + r) * (1. - z) + 2 * sqrt(r) * (1. + z), 5.);
 
  double p_g = 1.;
  double p_f = 1.;
  const double term3 = sqrt((mb + mass) * (mb + mass) - (mb - mass) * (mb - mass));
  for (int i = 0; i < 4; i++) {
    double term1 = sqrt((mb + mass) * (mb + mass) - vector_poles[i] * vector_poles[i]);
    double term2 = sqrt((mb + mass) * (mb + mass) - axialvector_poles[i] * axialvector_poles[i]);
    double z_p1 = (term1 - term3) / (term1 + term3);
    p_g = p_g * (z - z_p1) / (1 - z * z_p1);
    double z_p2 = (term2 - term3) / (term2 + term3);
    p_f = p_f * (z - z_p2) / (1 - z * z_p2);
  }
 
  double g = 1. / p_g / phi_g * (a_0 + a_1 * z);
  double f = 1. / p_f / phi_f * (b_0 + b_1 * z);
  double F1 = 1. / p_f / phi_F1 * (c_0 + c_1 * z + c_2 * z * z);
 
  double ha1 = f / sqrt(mb * mass) / (1. + w);
  double r1 = (w + 1.) * mb * mass * g / f;
  double r2 = (w - r) / (w - 1) - F1 / mb / (w - 1) / f;
 
  *a1f = (w + 1.) / 2. * rstar * ha1;
  *a2f = (r2 / rstar) * ha1;
  *vf  = (r1 / rstar) * ha1;
  *a0f = 0; // a0f is related to B->D* tau nu decay.
  // The class should not be used for taus, due to the lack of fitted parameters in a0f amplitude.
 
  return;
}

Member Data Documentation

◆ a0_0

double a0_0 {0}

private

0th-order z expansion coeffieient for scalar form factor f_0

Definition at line 103 of file EvtBGLFF.h.

◆ a0_1

double a0_1 {0}

private

1st-order z expansion coeffieient for scalar form factor f_0

Definition at line 106 of file EvtBGLFF.h.

◆ a0_2

double a0_2 {0}

private

2nd-order z expansion coeffieient for scalar form factor f_0

Definition at line 109 of file EvtBGLFF.h.

◆ a0_3

double a0_3 {0}

private

3rd-order z expansion coeffieient for scalar form factor f_0

Definition at line 112 of file EvtBGLFF.h.

◆ a_0

double a_0 {0}

private

B->D*lnu z expansion coeffieients

0th-order z expansion coeffieient for form factor g

Definition at line 118 of file EvtBGLFF.h.

◆ a_1

double a_1 {0}

private

1st-order z expansion coeffieient for form factor g

Definition at line 121 of file EvtBGLFF.h.

◆ ap_0

double ap_0 {0}

private

B -> Dlnu: ai_n (i = p —vector, 0 —scalar; n = 0,1,2,3) are free coefficients of z expansion in dispersion relation parametrization from C.G.Boyd, B.Grinstein, R.F.Lebed, Phys.

Rev. Lett. 74,4603(1995)

Chosen the order of series N=3, i.e. a_0 + a_1 * z + a_2 * z^2 + a_3 * z^3

Fitted values cited from R.Glattauer, etc. (Belle) Phys. Rev. D 93,032006 (2016). a+0, a+1, a+2, a+3 : 0.0126, -0.094, 0.34, -0.1 a00, a01, a02, a03 : 0.0115, -0.057, 0.12, 0.4

NOTE : This is the default BGL model in Belle II.

B -> D*lnu (l=e, mu): a_n, b_n (n = 0,1) and c_n (n = 0,1,2) are free coefficients of z expansion parametrization from C.G.Boyd, B.Grinstein and R.F.Lebed, Phys. Rev. D 56,6895(1997) & B.Grinstein, A.Kobach, Phys. Lett. B 771(2017)359-364

For the expansion of form factors g and f, the order of series N=1, i.e. a_0 + a_1*z For the expansion of form factors F1, the order of series N=2, i.e. c_0 + c_1 * z + c_2 * z**2 (g, f and F1 are the sub-terms of helicity amplitude)

Fitted values are taken from a private discussion of Florian Bernlochner based on B.Grinstein and A.Kobach, Phys. Lett. B 771(2017)359-364

It should not be used to generate D* with tau, due to the lack of fitted parameters in a0f amplitude. 0th-order z expansion coeffieient for vector form factor: f_+

Definition at line 89 of file EvtBGLFF.h.

◆ ap_1

double ap_1 {0}

private

1st-order z expansion coeffieient for vector form factor: f_+

Definition at line 92 of file EvtBGLFF.h.

◆ ap_2

double ap_2 {0}

private

2nd-order z expansion coeffieient for vector form factor: f_+

Definition at line 95 of file EvtBGLFF.h.

◆ ap_3

double ap_3 {0}

private

3rd-order z expansion coeffieient for vector form factor: f_+

Definition at line 98 of file EvtBGLFF.h.

◆ b_0

double b_0 {0}

private

0th-order z expansion coeffieient for form factor f

Definition at line 124 of file EvtBGLFF.h.

◆ b_1

double b_1 {0}

private

1st-order z expansion coeffieient for form factor f

Definition at line 127 of file EvtBGLFF.h.

◆ c_1

double c_1 {0}

private

1st-order z expansion coeffieient for form factor F1

Definition at line 130 of file EvtBGLFF.h.

◆ c_2

double c_2 {0}

private

2nd-order z expansion coeffieient for form factor F1

Definition at line 133 of file EvtBGLFF.h.

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

generators/evtgen/models/include/EvtBGLFF.h
generators/evtgen/models/src/EvtBGLFF.cc

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ EvtBGLFF() [1/2]

◆ EvtBGLFF() [2/2]

Member Function Documentation

◆ getbaryonff()

◆ getdiracff()

◆ getraritaff()

◆ getscalarff()

◆ gettensorff()

◆ getvectorff()

Member Data Documentation

◆ a0_0

◆ a0_1

◆ a0_2

◆ a0_3

◆ a_0

◆ a_1

◆ ap_0

◆ ap_1

◆ ap_2

◆ ap_3

◆ b_0

◆ b_1

◆ c_1

◆ c_2