options Struct Reference

Options for \(q\bar{q}\) functions. More...

Public Attributes
contribution_factors	contributions
double	alpha_s_mZ = QQbar_threshold::alpha_s_mZ
alpha_s_options	alpha_s_mu0
double	m_Higgs = QQbar_threshold::m_Higgs
double	Yukawa_factor = 1
double	invariant_mass_cut = std::numeric_limits<double>::quiet_NaN()
double	ml = 0
double	r4 = std::numeric_limits<double>::quiet_NaN()
double	alpha
double	mu_alpha
int	resum_poles = 6
SM	beyond_QCD
scheme	mass_scheme
production_channel	production = production_channel::all
bool	resonant_only
bool	expand_s
bool	double_light_insertion = false

Detailed Description

Options for \(q\bar{q}\) functions.

The default settings depend on the specific function. Members that are irrelevant to the considered function are ignored.

Member Data Documentation

contributions

contribution_factors contributions

Specifies multiplicative factors for various contributions

Option for cross section, energy level and residue functions

See also

contribution_factors

alpha_s_mZ

double alpha_s_mZ = QQbar_threshold::alpha_s_mZ

Specifies value of the strong coupling at the scale mZ

Option for cross section, energy level and residue functions.

See also

mZ, alpha_s_mu0

alpha_s_mu0

alpha_s_options alpha_s_mu0

Initial value:

= {
      std::numeric_limits<double>::quiet_NaN(),
      std::numeric_limits<double>::quiet_NaN()
    }

alpha_s_mu0 = {mu0, alpha_s} specifies a reference scale mu0 and the value alpha_s of the strong coupling constant at that scale. If set, this option overrides the alpha_s_mZ option.

For bottom-related functions decoupling to the four-flavour theory will be performed if mu0 is above the decoupling scale mu_thr. For lower values of mu0 it is assumed that alpha_s is given in the four-flavour theory.

Option for cross section, energy level and residue functions.

See also

mZ, alpha_s_mZ

m_Higgs

double m_Higgs = QQbar_threshold::m_Higgs

Specifies the value of the Higgs boson mass.

Option for cross section, energy level and residue functions.

Yukawa_factor

double Yukawa_factor = 1

Specifies a multiplier for the quark Yukawa coupling.

Option for cross section, energy level and residue functions.

invariant_mass_cut

double invariant_mass_cut = std::numeric_limits<double>::quiet_NaN()

Specifies an invariant mass cut for the non-resonant contribution

TODO: check The invariant mass of the final-state particles will be restricted to the region between m - invariant_mass_cut and m + invariant_mass_cut. By default, the loosest possible cut invariant_mass_cut = m - mW is taken, which yields the total cross section.

Option for cross section functions.

ml

double ml = 0

Specifies the value of the light (e.g. charm or bottom) quark mass

Option for all bottom- and top-related function. For the cross section functions, the implementation only includes corrections up to order = 1. For other functions also the corrections for order = 2 are included.

See also

double_light_insertion

r4

double r4 = std::numeric_limits<double>::quiet_NaN()

Third-order coefficient for conversion between pole and MS scheme

Specifies the non-logarithmic coefficient in the conversion between the pole and the MS scheme at order == N3LO.

r4 is mostly equivalent to \(c_m^{(4)}(\mu = m(m))\) in [27], but r4 refers to the theory with nl as opposed to nl + 1 active flavours.

Option for cross section, energy level and residue functions.

alpha

double alpha

Specifies the value of the running QED coupling constant.

Option for cross section, energy level and residue functions

mu_alpha

double mu_alpha

Specifies the scale for the running QED coupling constant.

Option for cross section, energy level and residue functions

resum_poles

int resum_poles = 6

Specifies the number of bound states that are resummed into the Green function.

Option for cross section functions.

See also

alpha_s, [Beneke:2014], [10]

beyond_QCD

SM beyond_QCD

Specifies the corrections beyond QCD that should be taken into account.

Option for cross section, energy level and residue functions.

See also

SM

mass_scheme

scheme mass_scheme

Specifies the renormalisation scheme and scale of the quark mass

Option for all bottom- or top-related functions

See also

mass_scheme

production

production_channel production = production_channel::all

Specifies which production channels are taken into account

Option for cross section functions.

See also

production_channel

resonant_only

bool resonant_only

Specifies whether only the resonant production should be computed

Option for cross section functions.

expand_s

bool expand_s

Specifies treatment of the global factor 1/s in the polarisation function

If set to true, 1/s is expanded around the threshold center-of-mass energy, i.e. the relation between the polarisation function and the PNRQCD Green function at leading order reads \(\Pi = \frac{N_c}{2m^2} G(E)\). If set to false, the factor is kept in unexpanded form, so that \(\Pi = \frac{2 N_c}{s} G(E)\) ar leading order.

Option for cross section and residue functions.

double_light_insertion

bool double_light_insertion = false

Specifies whether effects from a non-zero light quark mass on double potential insertions are taken into account.

Setting this option to true usually has a small numerical impact on the final result and leads to a considerable slowdown. The current implementation is comparably fast, but not very accurate. Furthermore, it is not thread safe.

Option for energy level and residue functions.